HEPATITIS VIRUS: reading this material will open your eyes to a whole lot of things

Hepatitis virus

1. HEPATITIS VIRUS

2. OUTLINE Introduction. General characteristics of hepatitis viruses. Epidemiology. Morphology\ virology. Pathogenesis. Clinical features. Complications. Laaboratory diagnosis. Prevention.

3. INTRODUCTION Viral hepatitis is a systematic disease primarily involving the liver. They can cause inflammation of the liver resulting in a clinical illness characterized by fever, GI symptoms (nausea, vomiting) and jaundice . Regardless of the virus type identical histopathologic lesion are observed in the liver. These viruses may present as acute or chronic diseases. Some may present as both.  

4. HEPATITIS VIRUSES Most cases of acute hepatitis are caused by: 1. Hepatitis A Virus - Hepatovirus , a picornaviridae 2. Hepatitis B Virus - Orthohepadnavirus , a Hepadnavaridae 3. Hepatitis C Virus - A flaviviridae 4. Hepatitis D Virus - deltaVirus 5. Hepatitis E Virus - a Caliciviridae 6. Hepatitis G Virus - an unnamed flaviviridae

5. HEPATITIS VIRUSES Other viruses known to cause sporadic hepatitis are Yellow fever Virus Cytomegalovirus Epstein-Barr Virus Herpes simplex Virus Rubella Virus Enteroviruses

6. GENERAL CHARACTERISTICS OF HEPATITIS VIRUSES All except HBV are RNA Viruses of the single standard type (SS RNA ). Only A&E are non-enveloped. While A and E are transmitted fecal-orally, B,C,D and G are transmitted parenterally .

7. GENERAL CHARACTERISTICS OF HEPATITIS VIRUSES Hepatitis A&E never cause chronic liver diseases, while B,C, and D often cause chronic disease . Hepatitis B and C have been associated with hepatocellular carcinoma.

8. Characteristics of Human Hepatitis Viruses Virus Family/ Genus Size/ Genome Length of Incubation Mechanism of transmission Vaccine HAV Picornaviridae / Hepatovirus 72 27-30 nm, single-stranged RNA 15-40 days Mostly oral-fecal Yes HBV Hepadnaviridae / hepadnavirus 142 nm, circular double-stranged DNA 50-180 days Parenteral Recom-binant subunit vaccine HCV Flaviviridae 30-50 nm single-stranged RNA 14-28 days Parenteral, likely other sources No HDV Unclassified 35-40 nm single-stranged RNA 50 180 days* Parenteral transmission No HEV Caliciviridae 27 34 nm single-stranged RNA 6 weeks Oral-fecal No

9. HEPATITIS A Hepatitis A (infectious hepatitis) is generally an acute, self-limiting infection of the liver by an enterically transmitted picornavirus , hepatitis A virus (HAV). Infection may be asymptomatic or result in acute hepatitis,Rarely fulminant hepatitis can ensue. Although the duration and severity of symptoms vary widely, hepatitis A infections never cause chronic liver disease

10. EPIDEMIOLOGY OF HEPATITIS A VIRUS Hepatitis A Virus is widespread globally. Transmission is feaco -oral through close personal contact in crowded and poor sanitation. HAV infection occurs at an early age, most children in such circumstances become immune by age 10.

11. EPIDEMIOLOGY OF HEPATITIS A VIRUS HAV is not usually transmitted by the use of contaminated needles and syringes or through blood administration . Incubation period ranges from 10-50 days (average 25-30 ). Infectious dose is 10⁸. The prevalence of anti-HAV increases with age . No carrier stage.

12. EPIDEMIOLOGY OF HEPATITIS A Peak infectivity occurs during the 2 weeks before onset of symptoms. Infectivity of stools is 14-21 days before onset of jaundice and 8 days after onset of jaundice. Highest concentration occurs during the 2 weeks before jaundice develops or liver enzymes increase.

13. EPIDEMIOLOGY OF HEPATITIS A VIRUS Cyclic patterns of disease with peaks every 5 to 10 years have been noted in some developed countries with temperate climates. certain groups are at increased risk of infection , including (1) patients and staff of institutions for the intellectually handicapped, where it is difficult to maintain high standards of hygiene (2) staff and children attending daycare centres especially large centers open to children in diapers.

14. EPIDEMIOLOGY OF HEPATITIS A VIRUS ; (3) homosexual men who engage in anal-oral contact . (4) intravenous drug users. (5) travelers from low-risk areas to endemic areas, particularly if they stay for extended periods. Travelers may return home while incubating the disease and spread it to their families.

15. Epidemiology of hepatitis A Common-vehicle for epidemics of hepatitis A is the consumption of contaminated food. Two mechanisms are recognized for foodborne spread of hepatitis A: clean food may be contaminated by a food handler who is incubating hepatitis A, or the food may have been contaminated at its source, such as may occur with shellfish. In many countries, an important mechanism of transmission is the consumption of raw or partially cooked shellfish

16. EPIDEMIOLOGY OF HEPATITIS A Other uncommon but documented include vertical transmission in first trimester and blood transfusion in the viraemic phase.

17. Virus Hepatitis A Family Picornaviridae Genus Hepatovirus Virion 27 nm icosahedral Envelope No Genome ssRNA Genome size 7,5kb Stability Heat- and acid-stable Transmission Fecal-oral Prevalence High Fulminant disease Rare Chronic disease Never Oncogenic No HEPATITIS A VIRUS

18. MORPHOLOGY OF HEPATITIS A VIRUS Hepatitis A Virus (HAV) is a picornavirus of the genus hepatovirus,only one serotype. It is a 27-28nM, spherical, non-enveloped particle with icosahedral symmetry containing a linear, positive-sense, single-stranded RNA genome . The stability of the virus appears to exceed that of all known picornaviruses .

19. MORPHOLOGY OF HEPATITIS A VIRUS HAV is partially resistant to heat and is still infectious after 10 to 12 hours at 60 C, stable under extremes of pH (3-9), resistant to ether and chloroform. HAV is inactivated by buffered saline after 4mins at 70 o C and immediately at 85 o C, hypochlorite, iodine and potassium permanganate, and autoclaving at 121ᵒC.

20. Morphology of hepatitisA HAV can remain viable for many years stored at -20ᵒC. HAV in dried form at room temperature maintains infectivity for several weeks.

21. PATHOGENESIS OF HEPATITIS A HAV is generally transmitted by the fecal-oral route. The virus is acid resistant, it probably passes through the stomach, replicates lower in the intestine, and is then transported to the liver, which is the major site of replication. Virus is shed from infected liver cells into the hepatic sinusoids and canaliculi , passes into the intestine, and is excreted in feces.

22. Pathogenesis of hepatitis A It has been postulated that liver cell damage occurs through a cell-mediated immune response, whereas circulating antibodies are probably more important in limiting the spread of virus to uninfected liver cells and other organs. It has been suggested that virally elicited T cells target infected liver cells and induce immunopathology .

23. Pathogenesis of hepatitis A Vallbracht found that lymphocytes from convalescing patients produced cytotoxic effects against autologous epidermal cell lines infected with HAV and that CD8+ T-cell clones demonstrated cytotoxic activity against autologous fibroblasts infected with hepatitis A. confirming the hypothesis that CD8+ T lymphocytes mediate liver cell damage. Furthermore, natural killer cells are capable of lysing HAV-infected cells.

24. Clinical features Hepatitis A is an acute or subclinical infection of the liver. Although the clinical expression of infection varies widely, the disease is usually self-limited and mild. The most important determinant of the severity of illness is age.

25. Clinical features CDC estimated that about 9% of the hepatitis A cases occurred in people older than 50 years but that about 72% of the deaths caused by hepatitis A occurred in that age group. Over 90% of infections in children younger than 5 years are silent.

26. Clinical features Patients with hepatitis A often describe a mild illness the prodrome that appears 1 to 7 days before the onset of dark urine, although longer periods have been recorded. In the early stages, flulike symptoms are common; fever (up to 40°C) accompanied by chills, mild headache, malaise, and fatigue. Loss of appetite with patients reporting that the sight or smell of food, especially fatty foods, is nauseating. Vomiting and weight loss is common.

27. Clinical features The first specific sign of disease and the one that causes most patients to seek medical attention is the onset of dark urine. Bilirubinuria is usually followed within a few days by pale or clay-colored feces and yellow discoloration of the sclera, skin, and mucous membranes. The return of color to the stool occurs 2 or 3 weeks after the onset of illness and is an indication of resolution of disease. Itching, a sign of cholestasis , occurs in less than 50% of patients.

28. Clinical features On physical examination, the patient's liver may be enlarged and sometimes tender. In adults the liver can be enlarged up to 14 cm in the vertical axis and has a firm consistency. The spleen is palpable in 5 to 15% of patients. Spider nevi may appear on the trunk and usually disappear during convalescence. Other physical findings occur rarely. The duration of illness varies, but by the third week most patients feel better, have lost their hepatomegaly , and have normal or nearly normal levels of serum ALT and aspartate aminotransferase .

29. complications complications of hepatitis A include cholestasis , prolonged and relapsing disease, fulminant hepatitis, triggering of chronic active autoimmune hepatitis, and autoimmune extrahepatic disease. The most serious complication of hepatitis A is fulminant hepatic failure, defined by the appearance of severe acute liver disease with hepatic encephalopathy in a previously healthy person.

30. complications Danger signs include excitability, irritability, insomnia, confusion, and severe vomiting. Laboratory and clinical evidence of deteriorating liver function, especially prolonged prothrombin times, correlates with the histologic picture of almost complete destruction of the hepatic parenchyma, with only a reticulin framework and portal tracts remaining.

31. COMPLICATIONS Extrahepatic complications include- Upper gastrointestinal bleeding 0.5-1.2 Thrombocytopenic purpura <0.1 (6 cases) Guillain-Barré syndrome <0.1 (4 cases) Pure red cell aplasia <0.1 (3 cases) Autoimmune hemolytic anemia <0.1 (2 cases) Transverse myelitis , optic neuritis.

32. Laboratory diagnosis Hepatitis A is not clinically distinguishable from other forms of viral hepatitis, although the diagnosis may be suspected in a patient with typical symptoms during an outbreak. Liver function tests , especially serum levels of ALT and AST, are sensitive measures of parenchymal liver damage but are not specific for hepatitis A.

33. Laboratory diagnosis Elevated levels of total serum IgM , a mild lymphocytosis , and occasional atypical mononuclear cells are commonly found in patients with acute hepatitis A but are not diagnostic of the disease. The diagnosis of acute hepatitis A is most commonly confirmed by detection of specific IgM in a single acute-phase serum sample. The hepatitis A-specific IgM antibody is usually present at the initial evaluation and may be detectable at the time of the first rise in ALT.

34. Laboratory diagnosis IgM anti-HAV can be detected in nearly 100% of patients with acute hepatitis A at their first clinical examination and remains positive in most for 3 to 6 months and for 12 months in up to 25% of patients. HAV or viral antigen can be detected in the stools of patients 1 to 2 weeks before symptoms develop, but such detection has little place in routine clinical diagnosis because the tests are not widely available and shedding is often complete before the patient seeks medical attention

35. Laboratory diagnosis Molecular-based diagnostic techniques, including hybridization and especially PCR, have been used in research laboratories when a highly sensitive test for the presence of HAV is required. Hepatitis A antigen and HAV particles can be detected in the cytoplasm of infected cells by immunofluorescence , immunoperoxidase staining, or thin-section electron microscopy

36. TREATMENT OPTIONS At present, no specific therapy is available for hepatitis A, and management is supportive. In the rare event of fulminant hepatitis, hospitalization and symptomatic supportive treatment become necessary. In most patients with hepatitis A, admission to the hospital is not indicated, provided that patients have access to good care.

37. TREATMENT OPTIONS If hospitalized, fecally incontinent patients, patients with diarrhea, and small children should be given a separate room and toilet. The necessity for bed rest seems to have been overstated because no objective evidence has been provided that bed rest or restriction of physical activity affects the outcome of disease.

38. TREATMENT OPTIONS Dietary restrictions, including prohibition of even modest amounts of alcohol, also seem to have little effect on outcome. Nevertheless, recommendation of abstention from alcohol has become conventional because alcohol has been linked with relapse of jaundice. All cases of hepatitis A except the fulminant hepatitisA will resolve without any chronic sequelae .

39. PREVENTION The most effective method of controlling hepatitis A and other enteric infections is through improved standards of hygiene and ssanitation , especially the provision of clean water. Good hygienic practices with particular emphasis on hand washing and restriction of activities of workers who are ill are of primary importance in the food preparation industry. These general measures are most important to prevent hepatitis A transmission from person to person in families and hospitals.

40. PREVENTION Travelers to developing countries should be advised to eat only properly cooked food and be careful of uncooked vegetables and shellfish. Even in the vaccine era, the maxim to prevent traveler's diarrhea, "boil it, cook it, peel it, or forget it," also applies to hepatitis A prevention.

41. PREVENTION Passive Immunization Before the licensing of hepatitis A vaccines, the mainstay of hepatitis A immunoprophylaxis had been passive immunization with pooled IG, which has been known in the past as gamma globulin or immune serum globulin. Even with the availability of vaccines, IG still has importance in hepatitis A prophylaxis, IG has proved useful for the prevention of hepatitis A in travelers, Peace Corps volunteers, and military personnel and even in postexposure prophylaxis in common-source or family outbreaks

42. PREVENTION IG is recommended for postexposure prophylaxis and for unvaccinated individuals who expect to be in a high-risk situation in less than 2 weeks. IG is also recommended for preexposure prophylaxis for anyone who cannot take the vaccine, usually because of known allergy to one of its components.

43. PREVENTION Active Immunization Active Immunization with hepatitis A vaccines Formalin-inactivated, cell culture-produced, whole-virus vaccines have now been approved in much of the world. Two HAV killed vaccines have been approved for use in the United States and widely throughout the world

44. PREVENTION Both vaccines are grown in MRC-5 cells, purified, inactivated by formalin, and formulated with alum as an adjuvant, Both vaccines begin to be effective about 2 weeks after a single intramuscular dose. For individuals who expect repeated exposure or require long-term protection, a booster dose is recommended 6 to 12 months after the initial vaccination.

45. HEPATITIS B VIRUS Hepatitis B virus (HBV) infection is one of the most common, widespread infectious diseases. HBV infection and its clinical sequelae are enormous health problems world wide.

46. HEPATITIS B Over 2 billion people world wide (~ 30% of the world’s population) are estimated to have been infected with the HBV at some point in their lives. 350 million (5%) chronically infected. Over 4 million annual incidence . About five hundred thousand deaths occur annually from chronic complications of HBV.

47. HEPATITIS B Approximately three quarters of the world’s population live in areas where there are high level of HBV infection. HBsAg carrier rates vary from 0.1% to 20% in different populations worldwide. Carrier rates are highest in countries with basic or limited medical facilities and lowest in countries with the highest standards of living.

48. NIGERIAN ESTIMATES POPULATION – approx. 140million HBsAg prevalence = 10-20% (14-28mil) Total deaths from HBV= 3-7 mil. Annual HBV deaths=200,000

49. HEPATITIS B 10 genotypes (A-H) of HBV have been identified based on genomic divergence. The prevalence of these genotypes varies world wide according to geographical region and ethnicity. Genotypes A and D are predominant in Europe, Africa and the USA, genotypes B and C are restricted to Asia and the USA; genotype E in Africa, genotype F in central and South America, genotype G in Europe, Japan and USA while the rare genotype H has been reported in Mexico, Japan and Nicaragua.

50. EPIDEMIOLOGY OF HEPATITIS B HBV is a ubiquitous, highly contagious virus in the hepadnariviridae family. It is about 100 times more infectious than the human immunodeficiency virus (HIV) and is stable on environmental surface for at least seven days. Transmission is through infected blood, organs and blood products, sexual contact with infected individuals, vertically from infected mother to child, infected needles, syringes, scalpels and by tattooing and ear piercing.

51. EPIDEMIOLOGY OF HEPATITIS B VIRUS Transmission from carriers to close contact by oral route or by sexual or other intimate exposure occurs. It is note worthy that blood, vaginal and menstrual fluids, and semen have been shown to be infectious. Transmission by feaco -oral route has not been documented. No seasonal or age group predilection has been recognized with HBV infections.

52. EPIDEMIOLOGY OF HEPATITIS B VIRUS In regions with low risk of HBV i.e. Western Europe and North America, infection is most common in young adults and most cases are due to injection drug use and high risk sexual activity. Conversely, in areas with high risk of HBV (Africa and Asia), infection is most common in infants and children because of close child hood contact and parental spread (transmission from mother to child during pregnancy or childbirth)

53. EPIDEMIOLOGY OF HEPATITIS B VIRUS The incubation period is 50-180 days (mean: 60-90). HBV establishes chronic infection especially in those infected as infants and is a major factor in the development of chronic liver disease and hepatocellular carcinoma in infected individuals.

54. Virus Hepatitis B Family Hepadnaviridae Genus Orthohepadnavirus Virion 42 nm, spherical Envelope Yes (HBsAg) Genome dsDNA Genome size 3,2kb Stability Acid-sensitive Transmission Parenteral Prevalence High Fulminant disease Rare Chronic disease Often Oncogenic Yes HEPATITIS B VIRUS

55. Morphology of hepatitis B The hepatitis B virion has a diameter of approximately 42 nm, It has an outer layer or envelope approximately 7 nm in width that contains HBsAg proteins and glycoproteins and cellular lipid, Enclosed by the envelope is an electron-dense 28-nm-diameter spherical internal core or nucleocapsid . The virion surface manifests HBsAg specificity, which is contained in the small, middle, and large HBsAg proteins that are the principal protein components of the viral envelope.

56. HEPATITIS B VIRUS:

57. Morphology of hepatitis B HBsAg proteins not only are components of the virion envelope but also are released from infected cells as components of small spherical particles. These are heterogeneous in size and appearance (diameters from approximately 16 to 25 nm and called 22-nm particles) and are filamentous or rod-shaped particles.

58. ANTIGEN OF HEPATITIS B VIRUS: HBsAg = surface (coat) protein ( 4 phenotypes : adw, adr, ayw and ayr) HBcAg = inner core protein ( a single serotype) HBeAg = secreted protein; function unknown

59. MORPHOLOGY OF HEPATITIS B The viral genome consists of partially double stranded circular DNA . The full length DNA minus strand (L or long strand) is complementary to all HBV mRNA, the positive strand ( S or short strand) is variable and between 50% and 80% of unit length.

60. Genome of HBV virus Genome: 3.200 nucleotídes S P C X

61. MORHOLOGY OF HEPATITIS B There are four open reading frames that encode seven polypeptides. These include structural proteins of the virion surface and core, a small transcriptional transactivator (x), and a large polymerase (p) protein that includes, DNA polymerase, reverse transcriptive , and Rnase H activities. The S gene has three in frame initiation codons and encodes the major HBsAg , as well as polypeptides containing pre-S2, pre-S1 sequences.

62. MORPHOLOGY OF HEPATITIS B The C gene has two in- frame initiation codons and encodes HBcAg plus the Hbe , which is processed to produce soluble HBeAg . The particles containing HBsAg are antigenically complex.each contains a group- specific,a , in addition to two pairs of mutually exclusive subderterminants , d\ y and w\r. thus four phenotypes of HBsAg have been observed adw,ayw,adr,ayr , and are useful in epidemiologic investigations.

63. gene P Pré S1 Pré S2 gene S gene C Pré C AgHBe AgHBc AgHBs DNA Polimerase HBV Genome

64. Morphoogy of hepatitis B Infectivity of the virus is lost after direct boiling for 2 mins , autoclaving at 121 o C for 20 mins or dry heat at 161 o C for 1 hour, 80% ethyl alcohol at 11 o C for 2 mins . The infectivity of HBV is retained when stored at 30 to 32 o C for at least 6 months and when frozen at -20 o C for 15 years.

65. MORPHOLOGY OF HEPATITIS B The virus is stable at 37 ⁰ C for 60 minutes and remains viable after beign dried and stored at 25⁰C for at least 1 week. HBsAg is stable at pH 2.4 for up to 6hrs, but infectivity is lost. Sodium hypochlorite 0.5% destroys antigenicity within 3 mins at low protein concentrations,but undiluted serum specimens require higher concentrations (5%). HBsAg is not destroyed by ultraviolet irradiation of plasma or other blood products.

66. HOW THE VIRUS REPRODUCES ?? 1. First the virus attached to a liver cell membrane. 2. The virus is then transported into the liver cell and into the cell nucleus where the replication process starts

67. 3. The core particle then releases it’s contents of DNA and DNA polymerase into the liver cell nucleus, the DNA short(+) strand is elongated, the (-) strand repaired to form covalently closed circular DNA 4. Transcription by host rna polymerase II produces messenger RNA 4 mrna ; HBs protein , HBc protein, the HBe protein, and other undetected protein and enzymes. Reverse transcriptase forms a complex with the genomic size mrna synthesizing the (-) strand. Reverse transcriptase constructs a complimentary DNA strand using the (-) DNA strand as template.rna is degraded as the (+) DNA strand is synthezised via DNA ploymerase .

68. 5. The cell then assembles ’live’ copies of virus. The nucleocapsid is enclosed in an envelope as it exits the cell, the extension of the short(+) DNA strand stops immediately as the virus leaves the cell.

69. 6. However because of the excess numbers of surface proteins produced many of these stick together to form small spheres and chains. These can give a characteristic “ ground glass” appearance to blood samples seen under a microscope. 7. The copies of the virus and excess surface antigen are released from the liver cell membrane into blood stream and from there can infect other liver cells.

70. TISSUE TROPISM Liver cells are clearly the most readily infected and permissive cells for HBV in vivo, and permanent eradication of HBV infection after liver transplantation suggests that liver is the only site of HBV replication. Tissue tropism appears to be controlled at least in part at the level of viral transcription, because the viral transcriptional enhancers and certain viral promoters are active in liver cells but are not at all or poorly active in other cell types.

71. Natural history of HBV infection HBV infection can cause both acute and chronic liver disease. In adults, because of the healthy immune systems, acute HBV infection usually resolves within 4-12 weeks and the patient recovers within six months . In most patients, symptoms are generally mild and infection does not generally require medical intervention. The remainder are asymptomatic.

72. Natural history of HBV infection Only about 2% of adult patients with acute HBV infection may develop fulminant disease. Chronic HBV is the common outcome in neonates and children, following HBV infection.

73. Determinants of acute and chronic HBV infection From Murray et. al., Medical Microbiology 5 th edition, 2005, Chapter 66, published by Mosby Philadelphia,,

74. Natural history of HBV infection The course of chronic HBV infection can be broadly divided into four phases. Immunotolerant, immune clearance, low replicative (inactive) and high replicative. It is important to note that HBV patients can transition between active and inactive stages systematically and thus activity of the disease needs to be monitored long term.

75. Natural history of HBV infection Chronic HBV infection is classified into two categories, depending on hepatitis B e antigen (HBeAg) status: i.e. HBeAg positive disease (called the wild type HBV) and HBeAg negative disease. HBeAg positive chronic HBV infection is characterized by high levels of serum HBV DNA ( 10 5 -10 7 copies /ml) and increased alanine aminotransferse (ALT) levels.

76. Natural history of HBV infection If untreated the majority of patients in this category maintain high levels of HBV replication and active liver necroinflammation which is associated with development of fibrosis. progression to cirrhosis and increased risk of hepatocellular carcinoma (HCC ).

77. Natural infection of hepatitis B HBeAg-positive disease can progress to HBeAg-negative disease and around 10% per year spontaneously seroconvert to inactive disease which may or may not be sustained. HBeAg negative chronic HBV infection is characterized by persistent but lower level HBV replication (10 5 -10 6 /ml) compared to HBeAg-positive disease. There is fluctuating levels of ALT, progressive necroinflammation and fibrosis. Spontaneous remission of HBeAg-negative disease is extremely rare.

78. NATURAL INFECTION OF HEPATITIS B The course, progression and outcome of chronic HBV infection differ depending on numerous factors, including gender, age at time of infection, stage of the disease at diagnosis, level of viral replication, host immune status and response, and concomitant infection with other parenterally transmitted viruses (e.g. HCV, HDV and HIV). Many patients with chronic HBV infection are asymptomatic often with no history of recognized acute hepatitis, and comprise a reservoir for spread of infection to others.

79. Natural infection of hepatitis B The presence of more than 10 3 copies/ml of HBV DNA identifies chronic carriers as potentially infectious. Seroconversion from HBsAg positive with development of HBs antibody and HBsAg- negative state occurs in ~1% per year. It can take between 15 and 25 years for the signs of liver damage from chronic HBV infection to become apparent. Progression to chronic hepatic insufficiency, cirrhosis or HCC may occur even in previously asymptomatic HBV infection.

80. Natural infection of hepatitis B Approximately 25% of HBV patients will die from cirrhosis or HCC as adults. Men have about 50% lifetime risk of death compared with 15% in women. Potential risk factors for developing HCC in patients with chronic HBV infection include acquisition early in childhood, presence of cirrhosis, chronic alcohol consumption and tobacco use.

81. Natural infection of hepatitis B Extra hepatic manifestations occurs in both acute and chronic infections and are believed to be mediated by circulating immune complexes. This includes: transient serum sickness-like syndrome, skin rash, arthralgia , polyarthritis , vasculitis , nephrotic syndrome, glomerulonephritis , mixed essential cryoglobulinaemia , polyarthitis nodosa , pancreatitis and pericarditis .

82. VIRAL MARKERS OF HEPATITIS B INFECTION HBsAg is usually the first viral marker to appear in the blood after HBV infection . The presence of this antigen is considered to be synonymous with active infection. HBsAg can be detected as early as 1 or 2 weeks and as late as 11 or 12 weeks after exposure to HBV when very sensitive assays are used

83. VIRAL MARKERS OF HEPATITIS B INFECTION In self-limited infections, HBsAg was found to remain detectable by complement fixation in the blood for 1 to 6 weeks in most patients, although it may persist for up to 20 weeks. Patients who remain HBsAg -positive for less than 7 weeks rarely appear to acquire symptomatic hepatitis. As symptoms and jaundice clear, the HBsAg titer usually falls and HBsAg becomes undetectable in most symptomatic patients several weeks after resolution of hepatitis.

84. VIRAL MAARKERS OF HBV INFECTION HBe Ag is another regular and early marker of HBV infection. Highly sensitive assays such as passive hemagglutination and radioimmunoassay have demonstrated that HBe Ag appears simultaneously or within a few days of the appearance of HBsAg in all or almost all primary infections, and its titer peaks and then declines in parallel with HBsAg .

85. VIRAL MARKERS OF HBV INFECTION The prevalence of HBe Ag declines constantly over the first 10 weeks after the onset of symptoms. HBe Ag usually disappears just before the disappearance of HBsAg in self-limited infections Patients who remain HBe Ag-positive for 10 weeks or longer appear likely to become persistently infected. Anti- HBe appears in most patients at the time HBe Ag becomes undetectable or shortly thereafter. Anti- HBe persists for 1 to 2 years after resolution of HBV infection

86. VIRAL MARKERS OF HBV INFECTION The third viral marker in order of appearance is DNA and DNA polymerase-containing virions . These particles, detected by their DNA polymerase activity or by hybridization for viral DNA, appear in the blood of most patients soon after the appearance of HBsAg . They rise to high concentrations during the late incubation period of hepatitis B and fall with the onset of hepatic disease.

87. VIRAL MARKERS OF HBV INFECTION A fourth marker of infection that appears in virtually all patients and before the onset of hepatic injury in most, is anti- HBc , the antibody directed against the internal antigen of virions . Anti- HBc can usually be detected 3 to 5 weeks after the appearance of HBsAg in the blood and before the onset of clinically apparent hepatitis.

88. VIRAL MARKERS OF HBV INFECTION Anti- HBc titers usually rise during the period of HBsAg positivity, level off, and eventually fall after HBsAg becomes undetectable. The highest titers of anti- HBc appear in the patients with the longest period of HBsAg positivity. Anti- HBc titers fall three- to fourfold in the first year after acute infection, and then drop more slowly. Anti- HBc can still be detected by immunoelectroosmophoresis 5 to 6 years after acute infection in most patients .

89. PATHOGENESIS OF DISEASE ASSOCIATED WITH HBV INFECTION The mechanism or mechanisms involved in liver cell injury during acute and chronic hepatitis B have been difficult to define, and at least three mechanisms that could play a role have been identified. The first (and considered by many to be the most important) is an HLA class I restricted cytotoxic T-cell (CTL) response directed at HBc Ag/ HBe Ag on HBV-infected hepatocytes .

90. PATHOGENESIS OF HBV INFECTION A second possible mechanism for hepatocyte injury in hepatitis B is a direct cytopathic effect of HBc Ag expression in infected hepatocytes . This possibility is suggested by the observation that cells in culture expressing HBc Ag (and not those expressing HBsAg alone) experience cytopathic changes and die. This indicates that HBc Ag expression can be toxic to cells and suggests that such a mechanism might operate in infected cells in vivo when HBc Ag is expressed.

91. PATHOGENESIS OF HBV INFECTION A third possible mechanism for liver cell injury in hepatitis B is high-level expression and inefficient secretion of HBsAg . This mechanism is suggested by observations in HBsAg transgenic mice expressing the large HBsAg protein alone. This protein is inefficiently secreted (secretion of the large HBsAg protein is facilitated by coexpression of the small HBsAg protein), accumulates in cells of the mouse liver, and results in liver cell injury.

92. PATHOGENESIS OF HBV INFECTION Such cells in the mouse have the appearance of the "ground glass" cells observed in human liver of some hepatitis B patients, which are cells containing large amounts of accumulated HBsAg . Whether HBsAg secretion is sufficiently blocked in any infected liver cells in vivo to cause liver cell injury by this mechanism in humans is not clear, but it is a mechanism that must be considered.

93. PATHOGENESIS OF HBV INFECTION A final mechanism for liver cell injury in some cases during HBV infection appears to be coinfection with a second cytopathic virus, the hepatitis delta virus (HDV). Delta antigen was discovered by immunofluorescent staining as a nuclear antigen distinct from HBsAg , HBc Ag, and HBe Ag in hepatocytes of some HBsAg carriers in Italy, which is the area with the highest prevalence of delta antigen.

94. PATHOGENESIS OF HBV INFECTION Delta antigen is contained in a 68,000-Da protein encoded by the HDV genome, which is a small single-stranded circular RNA with features of viroids . Virions of HDV consist of a core of delta antigen and RNA enclosed in an HBsAg -containing envelope. HDV appears to be a defective virus, and its replication requires coinfection with HBV. Phenotypic mixing results in delta antigen-containing particles with HBsAg -containing envelopes, and infection with the agent results in hepatic injury and suppression of HBV replication.

95. PATHOGENESIS OF HBV INFECTION There is a higher incidence of HDV infection in HBsAg -positive patients with acute and chronic hepatitis compared with asymptomatic carriers. Simultaneous infection with HBV and HDV may lead to severe or fulminant hepatitis more often than do infections with HBV alone, and cases of fulminant hepatitis B positive for delta antigen in populations with a high prevalence of delta agent have been observed.

96. Co-infections with HBV With HCV Co-infection of HBV with HCV may interfere with the replication of HBV , increase the severity of liver disease and increase the risk of fulminant hepatic failure, HCC and affect disease progression in chronic hepatitis C. With HDV Dual infection with HDV is often more severe and is associated with an increased risk for HCC compared with HBV infection alone.

97. Co-infections with HBV Super infection by HDV leads to acute hepatitis and cause progression to liver cirrhosis in a significant proportion of those with chronic HBsAg. With HIV Co-infection with HIV makes HBV infection more chronic leading to more severe liver disease, decreased HBeAg seroconversion and higher HBV DNA levels.

98. Co- infections with HBV HBV and HIV co-infection is associated with worse progression than HBV infection alone, and complicates management of HBV. It however does not appear to affect HIV outcome following highly active antiretroviral therapy.

99. Clinical features Acute hepatitis B- The clinical course of acute hepatitis B in individual cases is indistinguishable from that of acute hepatitis A. Among patients with acute icteric hepatitis B, between 10 and 20% have a serum sickness-like illness with an erythematous maculopapular rash, urticaria , arthralgias , occasional arthritis, and sometimes fever several days to weeks before the onset of clinically apparent liver disease.

100. Clinical features Symmetric involvement of distal joints or large joints is the rule. The symptoms usually last 2 to 10 days and clear without residual changes, although findings can persist for weeks or even months in unusual cases.

101. Clinical features Symptomatic acute hepatitis B can be mild and anicteric or more severe and associated with icterus . Typically, symptoms of headache, malaise, loss of appetite, nausea and occasionally vomiting, moderate fever (temperatures of 37.5°C to 39°C), and chilliness are present initially and appear 2 to 7 days before the onset of jaundice in icteric cases.

102. Clinical features Common physical findings include right upper quadrant tenderness, enlargement of the liver (up to 15 cm increase in vertical breadth), usually with a rounded tender edge; and scleral , mucous membrane, and cutaneous icterus . Massive hepatic enlargement is rare. The spleen can be palpated in 10 to 15% of patients. Mild enlargement of lymph nodes, particularly in the posterior cervical region, may be noted. Spider angiomats may develop and disappear after recovery. Transient gynecomastia occurs but is unusual. Children usually recover in 2 weeks and adults in 4 to 6 weeks.

103. Clinical features Laboratory tests may reveal normal or moderately reduced hematocrit and hemoglobin concentrations. Mild hemolysis is often observed. Total white blood cell count is usually normal and rarely exceeds 12,000 cells/mm3 . There may, however, be granulocytopenia and a relative lymphocytosis . Large, atypical lymphocytes are commonly present but rarely exceed 10%. Mild proteinuria may occur. Urobilinogen and bilirubin are common in the urine before the onset of jaundice and decrease in amount as jaundice progresses. Transient steatorrhea may occur early in the illness.

104. Clinical features Liver function abnormalities may include an increase in direct-reacting serum bilirubin early when total bilirubin is normal. Total serum bilirubin usually increases for 10 to 14 days and does not exceed 10 mg/dl in most patients. Occasional patients have higher values. The bilirubin concentration usually falls gradually over 2 to 4 weeks. The hallmark of acute viral hepatitis is the striking elevation in serum transaminase ( aminotransferase ) activity.

105. Clinical features Elevations may precede the onset of symptoms and usually peak in the first week of symptoms. Peak levels greater than 1000 units/ml are common, and serum alanine aminotransferase levels usually exceed serum aspartate aminotransferase levels. The peak level may correlate roughly with the extent of liver injury but is not a prognostic factor.

106. Clinical features Persistent infection with HBV is most often asymptomatic, but a significant number of patients chronically infected with HBV eventually experience cirrhosis. When HBV infection is associated with CPH, patients are generally in good health and have persistent or recurrent elevations of AST and ALT without jaundice.

107. Clinical features Persistent mild hepatomegaly is common and splenomegaly is occasionally present. Long-term follow-up of such patients shows no evidence of progression, and complete resolution occurs in some cases. Late disappearance of HBsAg occurs rarely.

108. DIAGNOSIS AND EVALUATION OF HBV INFECTION HBV is a antigenically heterogeneous virus and thus numerous serological molecular assays are necessary for definitive diagnosis. The accompanying liver inflammation and fibrosis is established using biochemical test, imaging and histology.

109. Diagnosis and evaluation of HBV infection Serological markers of infection HBsAg : indicates infectivity and is detectable in serum in nearly all individuals infected with HBV. It is the first detectable viral marker in blood after infection and is detectable from six weeks to six months after exposure. HBcAg is part of the HBV virion and is not detectable in serum. HBeAg detection in serum indicates active viral replication in the liver and high infectivity.

110. Diagnosis and evaluation of HBV infection Host immune markers of HBV infection Anti HBc ( IgM ) is the first antibody to appear in HBV infection and is detected in acute infection usually within one or two weeks of the appearance of the HBsAg . It usually disappears within six months, but may persist in some individuals with chronic HBV infection. Anti HBc IgG usually remains detectable for the lifetime of an infected individual.

111. Diagnosis and evaluation of HBV infection Host immune markers of HBV infection Anti HBc ( IgM ) is the first antibody to appear in HBV infection and is detected in acute infection usually within one or two weeks of the appearance of the HBsAg . It usually disappears within six months, but may persist in some individuals with chronic HBV infection. Anti HBc IgG usually remains detectable for the lifetime of an infected individual.

112. Diagnosis and evaluation of HBV infection Anti- HBe appear after anti- HBc , and it correlates with decreased infectivity and resolution of infection in HBeAg -positive patients. However this is not always the case in individuals with pre-core mutants who are HBeAg -negative, and HBsAg -positive with detected HBV DNA.

113. Diagnosis and evaluation of HBV infection Anti-HBs replaces HBsAg during resolution of acute HBV infection and persist for life in over 80% of patients with the presence of anti- HBc . Anti-HBs indicates immunity and titres >10U have been shown to be protective. It is detected in those who have cleared HBV infection and in those immunized, who however do not have anti- HBc.s

114. HBV - Diagnosis Acute Infection 0 2 4 6 HBsAg Anti-HBs Anti-HBc Anti-HBc IgM Months Years HBeAg HBV DNA Anti-HBe

115. Chronic Infection HBV - Diagnosis HBV DNA HBeAg Months Years Anti-HBc IgM Anti-HBc IgG Anti-HBe HBsAg

116. Diagnosis of hepatitis B Molecular diagnostic assays. HBV DNA measured in serum using signal amplification and target amplification techniques. Almost all HBsAg/HBeAg-positive patients have detectable HBV DNA in their serum. Most patients who recover from acute HBV infection do not have detectable HBV DNA in their serum, however, sensitive analysis of hepatic material may reveal persistent HBV DNA.

117. Biochemical markers These are used for assessment of liver disease and function, and include alanine amino trasnferase (ALT) serum albumin, globulin and prothrombin time etc. ALT – Released following lysis of infected hepatocytes – Indicator of necro -inflammatory disease

118. OTHERS Imaging Imaging techniques for detecting heterogeneities within the liver in HBV patients may include ultrasound examination, computed tomography, magnetic resonance imaging. These facilitates characterization of liver disease.

119. Liver biopsy This procedure, though invasive may be used to evaluate the extent and severity of liver damage in patients with chronic HBV infection. It is generally not indicated in acute HBV infection. Liver Histology – A more accurate indicator of liver disease than ALT – The Knodell scoring system (HAI score) – Allows assessment of disease state/progression/regression

120. Management of Hepatitis B Vaccination Available since 1982 Stimulates anti-HBs 3-4 inoculations over 3-4 months Confers 95% immunity Treatment Acute HBV requires no treatment (90-95% adults will resolve spontaneously) Current Treatment Options Thymosine - Adefovir Lamivudine - Entacavir Conventional IFN alfa - Combination Therapy (IFN + Lamivudine ) Pegasys (peg. IFN)

121. Treatment options in Nigeria Lamivudine Advantages: Oral formulation Good side-effect profile Can be used in decompensated liver disease. Disadvantages: Single mechanism of action Modest response rate Undefined treatment duration High viral rebound after cessation of therapy Poor efficacy in patients with high HBV DNA, low ALT Drug resistance due to YMDD mutants No longer recommended as first line in all treatment guidelines

122. treatment Conventional interferon alpha 2a ADVANTAGES: Dual mode of action- antiviral; immunomodulatory . Defined duration of therapy. Good rate of ‘s’ seroconversion in ‘e’ seroconverters . Good sustained viral suppression. No drug resistance. DISADVANTAGES: Thrice weekly injection. Less tolerable side effects. Modest response rates. Cannot be used in decompensated liver disease. Moderate response rate.

123. PEGylated Interferon

124. Addition of polyethylene glycol (PEG) moiety to protein results in 1 : Prolonged plasma half-life Reduced clearance Less immunogenicity Characteristics of new protein depend on 1,2 : Structure of PEG moiety ( eg , size, branching, linkage bond strength) Site(s) of attachment to parent compound

125. Advantages of pegilation Improved Pharmacokinetics ( t 1/2 , Cl, ) Less fluctuations in plasma concentrations Decreased toxicity Decreased immunogenicity and antigenicity Increased physiological and chemical stability Protection from proteolysis Increased compliance and patients QOL

126. ASLIN RECOMMENDATIONS FOR CHB TREATMENT IN NIGERIA Pegylated interferon alpha 2a 180mcg weekly for 24weeks in HBeAg + ve ; 48 weeks in HBeAg – ve patients. OR Conventional interferon alpha 2a 4.5miu or 9miu thrice weekly for 24 weeks in HBeAg + ve ; 48 weeks in HBeAg – ve patients. Lamivudine (per oral): 100mg daily for at least 12 months. Adefovir dipivoxil (per oral): 10mg daily for at least 12 months.

127. PREVENTION H/E for the public and health care providers Universal immunization (infants, children, adolescents) and implementation of NPI scheme for HBV vaccination. Screening and vaccination of at risk populations. Screening of pregnant women at ANC. Immunisation at birth of all babies born to HBV-positive mothers.

128. HBV - Vaccine Vaccine Age Group Dose Volume # Doses ( μ g) (ml) Engerix-B 0-19 yr 10 0.5 3 (mo 0,1,6)  20 yr 20 1.0 3 (mo 0,1,6) Adults on hemodialysis 40 2.0 4 (mo 0,1,2,6) Recombivax HB 0-19 yr 5 0.5 3 (mo 0,1,6)  20 yr 10 1.0 3 (mo 0,1,6) (Optional 2-dose) 11-15 yr 10 1.0 2 (mo 0, 4-6) Adults on hemodialysis 40 1.0 * 3 (mo 0,1,6)

129. Bivalent HAV and HBV vaccine 1ml contains 720 ELISA Units of inactivated HAV and 20 ug of recombinant HBsAg protein Dosage: 1 ml at 0, 1, 6 months Recommended for all susceptible persons  18 years at risk of exposure to both HAV and HBV, including travelers to areas of high/intermediate endemicity for both viruses Combined HAV and HBV - Vaccine

130. prevention Screening of all blood products. Proper Disposal of all sharps. Non recycling of sharps. Sterilisation of sharps used by traditional practitioners barbers etc. Easy availability of HB immunoglobulin. Safe coital practice.

131. HEPATITIS D Hepatitis D 1977: Mario Rizzetto and colleagues discovered HDV, also known as the delta virus Single-stranded, 1.7-kb RNA virus Co-infection with Hepatitis B required for packaging and release of HDV virions from infected hepatocytes . Viral particle is 36 nm in diameter and contains HDAg and the RNA strand, using HBsAg as its envelope protein.

132. Turin, Italy – Hepatitis D Site of discovery 1977

133. Epidemiology of hepatitis D HDV infects 5% of the world's 300 million HBsAg carriers Prevalence of HDV infection in South America and Africa is high with Italy and Greece being areas of intermediate endemicity . HDV in prostitutes in Greece and Taiwan is high IVDA most common mode of transmission: 17% to 90% coinfected

134. Epidemiology of hepatitis D The primary routes of transmission are similar to that of HBV though HDV does not appear to be a sexually transmitted disease. Infection is dependent on HBV replication, as HBV provides an HBsAg envelope for HDV. The incubation period varies from 2-12 weeks.

135. Epidemiology of hepatitis D Hepatitis D Three known genotypes are described Genotype I has a worldwide distribution Genotype 2 has been discovered in Taiwan, Japan, and northern Asia Genotype 3 is found in South America

136. Virus Hepatitis D Family Unclassified Genus Deltavirus Virion 35 nm spherical Envelope Yes (HBsAg) Genome ssRNA Genome size 1,7 kb Stability Acid-sensitive Transmission Parenteral Prevalence Low, regional Fulminant disease Frequent Chronic disease Often Oncogenic ? Characteristics of hepatitis D viruses

137. Hepatitis Delta Virus (HDV)

138. pathophysiology The hepatitis D virus is known to have cytopathic effects on the hepatocytes . high-level expression and inefficient secretion of HBsAg This protein is inefficiently secreted (secretion of the large HBsAg protein is facilitated by coexpression of the small HBsAg protein), accumulates in cells of the liver, and results in liver cell injury.

139. histopathology Hepatitis D: Histopathology Same as chronic HBV: classic histologic abnormalities: Inflammatory infiltrates: mononuclear cells may either remain contained within the portal areas or disrupt the limiting plates of portal tracts, expanding into the liver lobule (interface hepatitis)

140. histopathology Periportal fibrosis or bridging necrosis (between portal tracts) the presence of bridging necrosis places the patient at increased risk for progression to cirrhosis Ground-glass cells: the granular homogeneous eosinophilic staining of cytoplasm caused by the presence of HBsAg . Sanded nuclei reflect the presence of an overload of HBcAg

141. HDV INFECTION PATTERNS COINFECTION ACUTE SIMULTANEOUS INFECTION WITH HBV AND HDV OFTEN RESULTS IN FULMINANT INFECTION (70% CIRRHOSIS) SURVIVORS RARELY DEVELOP CHRONIC INFECTION (< 5%)

142. HDV INFECTION PATTERNS SUPERINFECTION RESULTS IN HDV SUPERINFECTION IN AN HBsAg CARRIER (CHRONIC HBV) CAN OCCUR ANYTIME DURING CHRONIC DISEASE USUALLY RESULTS IN RAPIDLY PROGRESSIVE SUBACUTE OR CHRONIC HEPATITIS

143. Clinical presentation Mirrors acute Hepatitis B alone: mild to severe Risk of developing chronic HBV and HDV infection after acute exposure to both viruses is the same (~5%). Chronic HBV and HDV disease tends to progress more rapidly to cirrhosis than chronic HBV infection alone. HDV superinfection may result in fulminant hepatic failure Greater than 60% can become cirrhotic.

144. Clinical presentation HDV-HBV coinfection . ACUTE HEPATITIS Symptoms: Preicteric phase: fatigue,lethargy , anorexia, nausea,headache for 3-7 days Icteric phase: jaundice,fatigue and nausea claycolored stools and dark urine.

145. HDV-HBV co-infection often asymptomatic Incubation period of 3 to 7weeks. manifested in single episode(simultaneous HBV/ HDVreplication ) or in twoepisodes ( sequentialHBV /HDV replication).

146. Coinfection clinical presentation Disease is over in 6 months HBV -HDV coinfection could lead to more severe casesthan HBV-only infection. Higher incidence of fulminant hepatitis Low incidence of chronichepatitis (1-3%).

147. Clinical presentation superinfection FULMINANT HEPATITIS jaundice, coagulopathy hepatic encephalopathy-changes in personality,disturbances in sleep,confusion , difficulty concentrating, occasionallyabnormal behavior.

148. Clinical presentation superinfection severe rare form of viral hepatitis results in acute, massive destruction of large portions of the liverMortality : 80%. indication for orthotopic liver transplantation ten times more likely thanHBV -only cases.

149. CHRONIC HEPATITIS D Large numbers of hepatocytes are already producing HBsAg . HDV replicates faster (incubation 3 weeks) Fatality rates from fulminant hepatitis up to 20%, Almost all superinfection cases proceed to chronic hepatitis.

150. Chronic hepatitis D Symptoms similar to acute hepatitis but less severe ongoing liver inflammation 70-80% develop cirrhosis compared to 15-30% with only chronic HBV infection Cirrhosis leads to liver failure and portal hypertension Death results from bleeding, hepatic coma, infection, or kidney failure.

151. diagnosis Serologic diagnosis of HDV infection: Results are positive for HDV antigen in 20%. Results are positive for HDV RNA in 90% with the reverse transcriptase polymerase chain reaction being the most sensitive assay for the detection of HDV viremia . Results for anti-HDV immunoglobulin M ( IgM ) are positive initially and then are positive for anti-HDV immunoglobulin G The finding of antibody to HDV is almost exclusively associated with chronic HDVinfections .

152. HDV - Coinfection Months HDV RNA IgM anti-HDV IgG anti-HDV HDAg IgG anti-HBc ALT HBsAg anti-HBs IgM anti-HBc

153. diagnosis Results for anti-HB core IgM are positive, except with superinfection , in which anti-HB core IgM is absent. ALT, AST levels greater than 500 IU/L, INR greater than 1.5 or a PT greater than 17 seconds may be the first evidence of fulminant liver failure. HBsAg is required for HDV replication but may be suppressed to undetectable levels with active HDV replication. In summary: HBcAb IgM distinguishes between coinfection ( HBcAb IgM –positive) and superinfection ( HBcAb IgM negative).

154. HDV - Superinfection ALT HDV RNA IgM anti-HDV IgG anti-HDV HDAg HBV DNA Years HBsAg, IgG anti-HBc

155. Treatment options. HBV & HDV coinfection : Less responsive to interferon therapy than patients infected with HBV alone. Lamivudine appears to be ineffective against HBV/HDV coinfection . Interferon alpha in high doses has been shown to effective.

156. PREVENTION No vaccine is available. In areas where hepatitis D is endemic vaccination with hepatitis B va

157. HEPATITIS C HISTORY 1973 : NON A, NON B HEPATITIS IS DESCRIBED 1989 : HEPATITIS C (HCV) GENOME IS CLONED; A SINGLE STRANDED, RNA VIRUS IN THE FLAVIVIRIDAE FAMILY 1989 : HCV ANTIBODY TEST IS DEVELOPED (ELISA) 1990 : HCV VIRAL LOAD TEST IS DEVELOPED TO DETECT HCV RNA IN SERUM (PCR TEST) 1998 : COMBINATION THERAPY WITH INTERFERON AND RIBAVIRIN IS APPROVED BY THE FDA 2001 : PEGYLATED INTERFERON IS APPROVED BY THE FDA

158. EPIDEMIOLOGY OF HEPATITIS C VIRUSES Hepatits C virus (HCV) infects an estimated 3% of the world’s population and an estimated 2% of the United States population. This is 5 times more people than HIV-1 (Ahmad and Alvarez, 2004). It has been estimated that over 170million people are chronic carrier. HCV is the leading cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma and is the leading cause of liver transplants.

159. Epidemiology of hepatitis C virus HCV sequences recovered from multiple geographic regions suggests that there are at least six major genotypes. a provisional identification of a seventh genotype in a specimen originating from central africa has been documented.

160. Epidemiology of hepatitis C The geographic distribution of HCV genotypes is not fully characterized,but some trends are apparent. the United States, 60%to 70 % of isolates are genotypes 1a or 1b genotype 4 infections are prevalent throughout Africa and the middleeast genotype2a and 2b occurs worlwide but in smaller percentages of the population. types 5 and6 have been reported in South Africa and Southeast Asia. genotype3 occurs in Asia, but has been linked in other geographic regions to illicit drug users.

161. United States 3-4 M Americas 12-15 M Africa 30-40 M Southeast Asia 30-35 M Australia 0.2 M Western Europe 5 M 170-200 Million (M) Carriers Worldwide Hepatitis C: A Global Health Problem Eastern Europe 10 M Far East Asia 60 M

162. Prevalence of HCV by world region HEPATITIS C ESTIMATED WORLD INFECTION PREVALENCE (BY WHO REGION) WHO Region Total Population (Millions) Hepatitis C Prevalence (Rate %) Infected Population (Millions) Number of Countries (by WHO Region) Where Data Unavailable Africa 602 5.3 31.9 12 Americas 785 1.7 13.1 7 Eastern Mediterranean 466 4.6 21.3 7 Europe 858 1.03 8.9 19 South-East Asia 1500 2.15 32.3 3 Western Pacific 1600 3.9 62.2 11 Total 5811 3.1 169.7 59 Data Source: Weekly Epidemiological Record No. 49 / Dec, 1999 / WHO

163. EPIDEMIOLOGY OF HEPATITIS C VIRUS HCV is transmitted primarily through direct percutaneous exposure to blood and blood products, through sexual contact with infected individuals, from mother to infants. The source of infection cannot be identified in 10% of cases . Incubation period averages 6-7 weeks. The average time from exposure to seroconversion is 8-9 weeks.

164. Transmission sources

165. How People Become Infected With Hepatitis C? Blood products Blood transfusions before 1992 Other blood products before 1987 Current transfusions no longer a major risk factor Injection (IV) drug use – 60% of all new infections High Risk:

166. How People Become Infected With Hepatitis C? Snorting cocaine or other drugs Occupational exposure Body piercing & acupuncture with unsterilized needle Tattooing Lower Risk:

167. How People Become Infected With Hepatitis C? From pregnant mother to child (during pregnancy or at birth - 5% - 8% risk) Risk increased if hepatitis C contracted during pregnancy HIV co-infection increases risk 4-fold Non-sexual household contacts (rare) Sharing razors and/or toothbrushes Sexual transmission Low risk in monogamous relationship Lower Risk:

168. HCV - Epidemiology Prevalence In Groups at Risk Recipients of clotting factors before 1987 75 - 90% Injection drug users 70 - 85% Long-term hemodialysis patients 10% Individuals with > 50 sexual partners 10% Recipients of blood prior to 1990 5% Infants born to infected mothers 5% Long-term sexual partners of HCV positive 1 - 5% Health workers after random needlesticks 1 - 2%

169. Virus Hepatitis C Family Flaviviridae Genus Hepacivirus Virion 60 nm spherical Envelope Yes Genome ssRNA Genome size 9,4 kb Stability Ether-sensitive, acid-sensitive Transmission Parenteral Prevalence Moderate Fulminant disease Rare Chronic disease Often Oncogenic Yes Characteristics of hepatitis C viruses

170. HCV virion structure Hypothesized structure: based on 3D structures of related viruses it consists of Icosahedral lipid membrane with E1/E2 glycoproteins that form heterodimers . Inside the viral membrane is thought to be an Icosahedral nucleocapsid ( penin et al, 2004).

171. HCV Genome 9.6 kb positive strand RNA genome 5’ (with IRES) and 3’ noncoding regions Open reading frame encoding polyprotein of ~3000 amino acids. The 5’ IRES (internal ribosomal entry site) is essential for cap-independent translation of viral RNA. The polyprotein of 3000 amino acids is translated as one single peptide which is then co- and post- transcriptionally processed by viral and cellular proteases (reviewed in Moradpour and Blum, 2004).

172. C E1 E2 p7 NS2 NS3 NS4A NS4B NS5A NS5B Core protein (nucleocapsid) Envelope glycoprotein-1 Envelope glycoprotein-2 Viroporin ? Zn-dependent proteinase Zn-dependent proteinase, serine protease, helicase NS3 cofactor ER-derived membranous web formation Unknown function; component of replicase? RNA dependent RNA polymerase HVR-1 HVR-2 5’ UTR 3’ UTR ORF

173. HCV genome Diagram of HCV RNA genome with encoded proteins (reviewed in Ahmad and Alvarez, 2004; Penin et al, 2004). E2 contains two hypervariable regions (HVRs) and is the most genetically variable region of the HCV genome, This allows for evasion of host immune responses by the virus. p7 is thought to belong to the viroporin family and may aid in viral maturation and release. Expression of NS4B leads to the formation of a membranous web derived from the host cell endoplasmic reticulum.

174. HCV genome This is thought to act as a scaffold with which viral RNA and proteins can associate during viral replication. All of these proteins are possible drug targets; however, the envelope glycoproteins may be less effective targets as they are so variable. NS5B, the RNA polymerase, is the target of polymerase inhibitors in development, and NS3 is the target of a promising protease inhibitor (see “Novel Drug Therapies”).

175. Protein F Newly discovered protein F Produced by ribosomal frameshift mutation around codon 11 of Core protein Function unknown Blood serum of infected individuals contains antibodies against protein F, so it appears that this protein is expressed in persons with HCV ( Shoukry et al, 2004). The function of this protein, however, and how often it is expressed are unknown.

176. Hepatitis C Life Cycle www.rockefeller.edu/pubinfo/hepc.jpg CD81?

177. HCV replication Steps in the HCV life cycle: HCV virus infects human. 2. Binding to unidentified cell surface receptor and internalization into host liver cell. (CD81 receptor is essential but not sufficient for viral binding; CD81 is present on the surface of almost all nucleated cells as a complex with a variety of other cell-surface receptors)

178. HCV REPLICATION 3. Cytoplasmic release and uncoating of RNA genome 4. IRES-mediated translation and polyprotein processing by cellular and viral proteases 5. RNA replication (creation of minus strand template followed by production of plus strand RNA copies) 6. Packaging and assembly 7. Virion maturation

179. HCV REPLICATION 7. Virion maturation 8. Release from host cell. it is known that HCV binds to a receptor on the cell surface, undergoes translation and replication inside the cell, and new viruses are then released from the cell, the details of the life cycle are largely unknown and have been hypothesized based on the life cycle of closely related viruses.

180. VIRAL TROPISM HCV replicates within the hepatocyte , and the liver-specific expression of miR122 may contribute to this specificity . However, replication may also occur in other cell types HCV RNA also has been detected in cutaneous lesions of personswith HCV-related cryoglobulinemia and vasculitis , in renal biopsiesof patients with HCV-associated membranoproliferative glomerulonephritis .

181. NATURAL HISTORY AND PATHOGENESIS VIRAL PERSISTENCE; HCV RNA can be detected in plasma within days of exposure, often 1 to 4 weeksbefore liver enzyme levels rise. Viremia peaks in the first 8 to12 weeks of infection, then drops to lower levels and persists.

182. Viral persistence In some instances, plasma HCV RNA becomes undetectable in the first few months and remains undetectable indefinitely ( viralclearance ); in other instances, viremia is inconsistently detected early and a stable pattern of recovery or persistence is not evident for morethan 6 months. intermittent viremia may reflect reinfection , which has been observed in active injection drug users. rebounding viremia may represent escape from an initially successful immune response. Overall, viremia persists in 50% - 85% of acutely infected persons

183. Disease statistics Infected Individuals Persistent Infection Liver Disease Death 85% 30% 1-5% Most patients are asymptomatic and unaware they’re infected

184. Viral persistence The role of the host in viral persistence is evident in common source outbreaks in which a large number of persons were accidentally infected with the same HCV inoculum and only some recovered. In addition, HCV infection more often persists in African Americans than whites and in persons infected with HIV, compared to immunocompetent persons. Persons also are more likely to clear HCV infection if they develop clinical symptoms (i.e., become jaundiced), which correlates with amore vigorous immune response. Nonetheless, it has been difficult to define the immunologic mechanisms of HCV persistence and their genetic determinants .