Hepatitis viruses

This powerpoint contains slides describing types of hepatitis viruses, pathogenesis, clinical course, laboratory diagnosis, treatment and prevention against hepatitis viruses. This presentation is intended to use by medical students, nurses, paramedics in the learning on virology. The slided could also be resource materials for the academicians.

1. Dr. Tarek Mahbub Khan
MBBS, M.Phil (virology)
Assistant Professor

2. Learning objectives
•Definition of hepatotropic virus and examples
•Outline of classification and characteristics of
hepatitis viruses
•Structure, epidemiology, pathogenesis, clinical
outcome and laboratory diagnosis of: outcome and laboratory diagnosis of:
–Hepatitis A virus
–Hepatitis B virus
–Hepatitis C virus
–Hepatitis D virus
–Hepatitis E virus
–Hepatitis G
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3. •Viral hepatitis is a systemic
diseasecausedbyhepatitis
viruses that produce acute
inflammation of the liver
clinically
characterized
by
VIRAL HEPATITIS
clinically
characterized
by
fever, gastrointestinal
symptoms like nausea,
vomitingandjaundice.
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4. HEPATOTROPIC VIRUSES •Viruses which infects hepatocytes are hepatotropic
•Two broad classification:
•
Primary hepatotropic
:
Infects liver cell primarily:
•
Primary hepatotropic
:
Infects liver cell primarily:
–e.g., Hepatitis A, B, C, D, E and G viruses
•Secondary hepatotropic
: Hepatitis occurs as a
consequences to infection of other organs:
–e.g., CMV, Yellow fever virus, HSV, Dengue viruses
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5. AN OVERVIEW OF HEPATITIS
VIRUSES
Viruses Genome On-set of
infection
Transmission Chronicity
HAV RNA Children Feco-oral No HBV
DNA
Adult,
Parenteral,
Yes
HBV
DNA
Adult, children
Parenteral, Sexual, Vertical
Yes
HCV RNA Adult Parenteral, sexual Yes
HDV RNA Adult Parenteral, sexual Yes
HEV RNA Adult Feco-oral No
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6. HEPATITIS A VIRUS
(cause infectious hepatitis)
•Hepatitis A is non-envelop RNA virus
•ssRNA genome
•Possess seven genotypes (only one serotype)
•Virus family: Picornaviridae
•Genus: Hepatovirus
•Can be killed by autoclaving,
boiling
for 5 minutes,
heating food
(185
0
F for 1 minute), disinfection by
bleach
(1:100 concentration)
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7. •Incubation periods: 10-50 days
•Children are asymptomatic (80-95%) in relation to a dult
(10-25%)
•
Viremia : Transient
•
Viremia : Transient
•Virus in stool: 2 weeks before and 2 week after ja undice
•Onset of infection is abrupt
•ALT level remains high up to 1-3 weeks
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8. Epidemiology of HAV infection
•Transmission is mainly fecal-oral route. Sexual and
intravenous route is not common
•
Common in families, institutions, summer camp, day
•
Common in families, institutions, summer camp, day care, over crowded and poor sanitary conditions
•Sources of infections: Raw oysters, undercooked foo ds,
frozen strawberries and non-human primates
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10. •Virus attaches with a glycoprotein receptor (HAV ce ll
receptor 1 glycoprotein-
HAVCR1
) on hepatocyte
•HAV itself is not cytopathic
•
Cellular immunity particularly CD8+T cell , plays a key
•
Cellular immunity particularly CD8+T cell , plays a key role in cell injury
•IgM appears in blood at the onset of symptoms
•IgG confers lifelong immunity against all strains
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11. Immunological and biological events in HAV infectio n
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12. Laboratory diagnosis
•SAMPLES: Blood, Stool, bile , liver
•COMON METHODS: ELISA, PCR, Hybridization
•
SEROLOGICAL MARKERS (Anti
-
HAV)
:
•
SEROLOGICAL MARKERS (Anti
-
HAV)
:
•IgM
: Acute infection, decline to non-detectable range by 3-6 months
•IgG
: Indicates past infection, detected even after dec ades
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13. Management
•TREATMENT: Supportive
•PREVENTION:
•Improvement of personal hygiene and sanitation
•
Treatment with 0.5% sodium
hypochloride
solution
•
Treatment with 0.5% sodium
hypochloride
solution
•Vaccination
: Formalin inactivated vaccine
•HAV Igcan be given to person within 2 weeks of infe ction
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14. Because
–Most infected people are
contagious 10-14 days before
symptoms occursWhy hepatitis A spread
readily in a community?
symptoms occurs
–90% of the infected children
and 25%-50% of infected
adults have inapparent but
productive infections
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15. HEPATITIS B VIRUS
(serum hepatitis)
•DNA envelope virus
•Icosahedral capsid
•
Family: Hepadnaviridae Family: Hepadnaviridae
•dsDNA genome with incomplete positive strand
•Virus posses reverse transcriptase that acts in lat er part of
replication
•DNA integrates with host cell DNA by enzyme integr ase
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16. HOSTS OF HEPATITIS B VIRUS
Woodchuck
Ground squirrel
Duck
Human
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17. Basic structure of hepatitis B virus
•Antibodies are formed against all types of viral an tigens
•HBsAg is a part of the viral envelope 14/1/201817 Dr.Tarek/[email protected]/2015

18. HBV Particle HBV Particle
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19. Electron microscopic picture of HBV
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20. STRUCTURE OF HEPATITIS B VIRUS
•DANE PARTICLE: A 42 nm complete virion of HBV
•VIRAL CORE:
–Contains a partially double stranded DNA of only 3.2 kbp
–Enzymes: Protein kinase and DNA polymerase having both
reverse transcriptase
and
ribonuclease H
activity
reverse transcriptase
and
ribonuclease H
activity
–A P protein attached to its genome
–An icosahedral capsid formed by hepatitis B core antigen (HBcAg)
–HBeAg shares most of its protein sequence with HBcAg
•VIRAL SURFACE:
–An envelope containing three forms of glycoprotein hepatitis B surface
antigen (HBsAg)
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21. HEPATITIS B VIRUS GENOME
‘S’ gene
: HBsAg
Four open reading frame (ORF)
‘P’’ gene
: Polymerase Enzyme
‘X’ gene
:
Transactivation of transcription
‘C’ genes
: HBcAg, HBeAg
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22. HEPATITIS B SURFACE ANTIGEN
•HBsAg containing particles are released into the se rum and
outnumber the actual virion.
•Originally termed as Australian Antigen
•This antigen is immunogenic
•
HBsAg includes three glycoproteins (L, M and S)
•
HBsAg includes three glycoproteins (L, M and S)
•S glycoprotein is the major component of HBsAg part icle
•The glycoproteins of HBsAg have group specific and type
specific determinants:
–Group specific determinants: ‘a’
–Type specific determinants: ‘d’ or ‘y’ and ‘w’ or ‘ r’
•Combination of these antigens forms eight subtypes of HBV
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23. HBV REPLICATION
•HBV replication is unique because:
–Defined tropism for liver
–Small genome
–
Replicates through an RNA intermediate
–
Replicates through an RNA intermediate
–Produce and releases antigenic decoy particles
(HBsAg) 14/1/2018 Dr.Tarek/[email protected]/201523

24. ATTACHMENT AND ENTRY
•ATTACHMENT
to the hepatocytes is mediated by HBsAg
glycoprotein and several liver cell receptors:
–Transferrin receptor
–
Asialoglycoprotein receptor Asialoglycoprotein receptor
–Human liver annexin V
•ENTRY:
HBsAg binds to polymerized human serum albumin
and other serum proteins that may facilitate virus uptake by
the liver
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25. TRANSFER OF CORE TO THE NUCLEUS
•HBV core is transfer to the nucleus probably through m icrotubules.
•Capsid deliver the genome alongside with its own RNA polyme rase
inside the nucleus.
•DNA REPAIR
: incomplete positive strand is made complete with host
DNA polymerase and a cccDNA of HBV is formed. DNA polymerase and a cccDNA of HBV is formed.
•EARLY TRANSCRIPTION
: This cccDNA is transcribed to several different
length mRNA (pre-genomic RNA) by virion RNA polymerase:
–3500-base mRNA: encodes HBcAg, HBeAg, DNA polymerase and primer
–2400-base mRNA : encodes large (L) HBsAg glycoprote in
–2100-base mRNA : encodes medium (M) and small (S) g lycoproteins
–900-base mRNA : encodes the ‘X’ protein
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26. EXIT OF THE mRNA TO THE
CYTOPLASM
•mRNA exit to the cytoplasm through nuclear pore
•mRNA is read on host cell ribosome to translate dif ferent
proteins including DNA polymerase
•
FUNCTIONS OF HBV DNA POLYMERASE
:
•
FUNCTIONS OF HBV DNA POLYMERASE
:
1. Priming: start synthesizing a negative DNA stran d from the RNA
strand
2. Ribonuclease H activities: Cleaves the RNA strand that has been used
to synthesize DNA strand except a little RNA at the 3’ region of mRNA
3. Completion of genome synthesis
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27. FINAL STEPS IN REPLICATION
•ENCAPSIDATION:
–3.5 kb-base RNA (pre-genomic RNA) is encapsidized b y structural
protein (HBcAg)
•SYNTHESIS OF NEGATIVE STRAND
:
–Use 3.5 kb RNA as template
–
Catalyst by DNA polymerase with reverse transcripta se activity.
–
Catalyst by DNA polymerase with reverse transcripta se activity.
–RNAaseH will cleave the initial RNA template except few nucleotides
•SYNTHESIS OF POSITIVE STRAND
:
–The small RNA primer at the 5’ end of the newly syn thesized negative
DNA strand will start synthesizing positive strand
•RELEASE
:
–Provirus traveled through ER and Golgi body and acq uire its envelope
and released by budding
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28. REPLICATION OF HBV
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29. HEPATITISB PREVALENCE
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30. SPREAD OF HBV IN THE BODY
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31. PATHOGENESIS OF
HEPATITIS B INFECTION
•Transmission:
Parenteral, Sexual ,Vertical
•Liver damage:
1. Virus reaches the hepatocytesand attached by rece ptor and
displayed on cell surface displayed on cell surface
2. CytotoxicT lymphocyte mediates an immune attack against
viral infected cells
3. Results in inflammation and cell necrosis –Hepati tis
4. Antigen-antibody complex can be deposited in diff erent organs
and produce inflammation (eg. Arthritis,vasculitis)
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32. CLINICAL OUT COME OF
HEPATITIS B INFECTION
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33. OUTCOMES OF AGE OF
INFECTION
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34. CLINICAL FEATURES
•Two clinical types
1. Acute hepatitis
2. Chronic hepatitis •
Incubation period: 10
-
12 weeks
•
Incubation period: 10
-
12 weeks
•Many cases are asymptomatic
•Fever, anorexia, nausea, vomiting and jaundice
•Dark urine, pale feces, arthralgia, arthritis, rash
•Most chronic carriers are asymptomatic
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35. CLINICAL AND SEROLOGICAL EVENTS OF
HBV
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37. SIGNIFICANT OF HBV
SERO-MARKERS
Viralmarkers Significance HBsAg Acute infection, if persists for more than six
months: chronic infection
Anti-HBs Protection: by natural infection or vaccina tion
Anti-HBcAg IgM: Acute infection
IgG: Past or chronic infection
HBeAg Activeviral replication and high chance of
transmissibility
Anti-HBeAg Disease recovering
HBV-DNA Activeviral replication and high chance of
transmissibility
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38. LABORATORY DIAGNOSIS
1. Sample: Blood(serum plasma)
2. Serology:
–Methods
: Agglutination test, ICT, ELISA
–Acute infection
: HBsAg, anti-HBcAg(IgM), Anti-HBs
–Chronic infection or carrier
: HBsAg (>6 months), Anti-HBcAg,
HBeAg
(active viral replication)
HBeAg
(active viral replication)
–Window period
: Anti-HBcAg(IgM)
3. PCR:
–HBV-DNA in acute and chronic infection. Used for pr ognostic
parameter. Viral load >10
5
copies/ml: Active infection
4. SGPT, Serum bilirubin: Increased
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39. MANAGEMENT OF
HEPATITIS B INFECTION
A. Acute infection
: Supportive treatment
B.
Chronic hepatitis B infection
B.
Chronic hepatitis B infection –Alpha interferon, Lamivudin, Adefovir
TREATMENT
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40. C. Prevention strategy:
–Safe blood transfusion, safe sex, elective Caesarean
section
–Vaccines
: Recombinant Hepatitis B vaccine contains
HBsAg antigens
PREVENTION
HBsAg antigens
–Prophylaxis
: Hepatitis B immunoglobulin after accidental
exposure( eg. Needle stick injury)
–Newborn in infected mother: Both vaccine and HBIG
–Elective cesarean section
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41. COMPLICATION OF
HEPATITIS B INFECTION
•Cirrhosis of liver •
Hepatocellular carcinoma
•
Hepatocellular carcinoma
–FACTORS:
•Integration of HBV-DNA into host cell DNA
•Transactivation of transcription by X gene expressi on
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42. HEPATITIS C
•RNA envelope virus
•Family: Flaviviridae
•Genus: Hepacivirus
•Related to postranfusional NANB hepatitis
•Genome encodes:
–One core protein, two envelope glycoprotein and sev eral NS
proteins
–Six major genotypes(Clades) and more than 100 subty pes
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43. GENOME OF HCV VIRUS
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44. SIGNIFICANCE OF GENOMIC
DIVERSITY
•Different genotypes(1-6) are prevalent in different parts of the world
•Virus undergoes sequence variation in chronic infec tion
•Treatment response depends on genotypes
•QUASI-SPECIES
a complex viral population presents in a single inf ected individual
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45. EPIDEMIOLOGY
•3% of the world population has been infected (WHO, 1997)
•Mode of transmission: Parental, sexual, saliva , or gan transplant
•
HIGH RISK INDIVIDUALS:
•
HIGH RISK INDIVIDUALS:
–Intravenous drug users
–Hemophiliacs (Multiple blood transfusion)
–High risk sexual partners
–Health workers
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47. HCV INFECTION
•Incubation period: 6-7 weeks
•Antibody appears 8-9 weeks after exposure
•Antibodies are developed against core, envelope, NS 3 and NS4
proteins proteins
•70-90% of infected individual develop chronic hepa titis
•10-20% of chronic HCV infection leads to:
–Chronic active hepatitis
–Cirrhosis (20-50%)
–Hepatocellular carcinoma (5-25%)
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48. •Hepatitis C viral infection is more dangerous.
•REASONS:
–
70
-
90% of HCV infections progress to chronic hepatitis
HCV
OR
HBV
?
WHICH ONE IS MORE DANGEROUS?
–
70
-
90% of HCV infections progress to chronic hepatitis
–Inapparent infection is more in HCV than HBV
–Delay in development of antibody even in low titer
–No vaccine is available due to antigenic diversity of HCV
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49. LABORATORY DIAGNOSIS
•SAPMLE: Blood (Serum, Plasma)
•METHODS OF TEST: ELISA, ICT, RIBA, RT-PCR
•SEROLOGY(Anti-HCV):
–In 50-70% cases antibody appears with symptoms
–In other cases antibody appears in 3-6 weeks time
–Can not be distinguish between acute, chronic or re solved infection
•RT-PCR:
–Detects viral RNA
–Useful in prognosis after antiviral drug
–Used to detect genotypes to guide anti-viral therap y
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50. ALGORITHAMS OF HCV INFECTION
DIAGNOSIS
Anti-HCV (Screening)
POSITIVE
NEGATIVE
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NEGATIVE
HCV-RNA/anti-HCV core Ab
Repeat after 3 months
POSITIVE

51. RECOMBINANT IMMUNOBLOT
ASSAY (RIBA)
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RIBA detects more specific HCV antibodies. Test is
interpretedaspositive(2ormoreantigens)indeterminate(1
antigen) , negative (0 antigen). More specific than ELISA.
HCV-RNAhasnowreplacetheimportanceofRIBA.

52. LIMITATIONS OF THE
SEROLOGICAL TEST
•Limitations of the serological test:
–Long delay (even >6 months) in development of anti- HCV
antibody antibody
–Reactive screening test does not distinguish betwe en
current and past infection
–False reactive test result
–Cannot provide information about treatment response
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53. MANAGEMENT
•TREATMENT
–Alpha interferon or pegilated interferon
–Lamivudine
–Relapse is common
•PREVENTION
–No vaccine developed
–Practicing safe sex, blood transfusion, prohibiting IV addiction,
safe organ donation may protect
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54. HEPATITIS D VIRUS
•RNA envelop (HBsAg) virus
•Virus contains a single stranded negative sense RNA genome
•
Is a defective virus: Needs HBsAg for effective inf ection
•
Is a defective virus: Needs HBsAg for effective inf ection
•One serotype
•RNA genome encode one core protein: Delta antigen
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56. Co-infection and super
infection with HBV •Simultaneous infection of HBV and HDV results in co -infection •HDV infects in preexisting HBV infection results in super infection
•Fulminant hepatitis is associated with super-infect ion
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57. •In co-infection
–HDAg, HDV-RNA and anti-HDV IgM
–All markers of HDV replication disappear in convale scence
stage, even anti-HDV antibody disappear within mont hs
LABORATORY DIAGNOSIS
•In super-infection
–Persistence of high level of anti-HDV IgM and IgG, HDAg,
HDV-RNA
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58. HEPATITIS E VIRUS
•Non enveloped positive sense ssRNA virus
•FAMILY: Hepeviridiae
•GENUS: Hepevirus
•Most common cause of water borne epidemic in Asia, Africa, Mexico
•20% of pregnant women develops fulminant hepatitis
•Detection of anti-HEV antibody in blood helps diagn osis
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59. HEPATITIS G VIRUS
•Belongs to Flaviviridae family
•RNA envelope virus
•HGV is also known as GB virus C
•Transmitted through parenteral and sexual route
•
Have strong significance in HIV co
-
infection (35% cases)
•
Have strong significance in HIV co
-
infection (35% cases)
•HGV interfere HIV virus replication lower mortality rate
•Laboratory detection:
–GBV-C RNA detection
–Anti-GBV-C antibody
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60. PATHOLOGIC CHANGES IN HEPATITIS PATHOLOGIC CHANGES IN HEPATITIS
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61. Histology of Chronic hepatitis
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Right
: Granular cytoplasm, ground-glass hepatocytes
Left
: Immunoperoxidase test for HBsAg (HBsAg particles in
cytoplasm of hepatocytes

62. 1. HAV is a picornavirus
2. HAV can be detected in the blood 2 weeks prior to jaundice
3. Anti-HBcAg IgM is an useful viral marker in acute H B
infection
4.
Viral cytopathic effect is the main pathogenesis in liver
4.
Viral cytopathic effect is the main pathogenesis in liver damage by HBV
5. Reverse transcription occurs in the initial stage of HBV
replication
6. 70-80% of HCV infection leads to chronic hepatiti s
7. Quasi-species is observed in HEV infection
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63. 8. HDAg is detected in co-infection only
9. HDV genome is a ssRNA with positive polarity
10.HEV commonly infects adults
11.HEV is a flavivirus
12.
Fulminant hepatic failure is frequently observed in pregnant
12.
Fulminant hepatic failure is frequently observed in pregnant women with HEV infection
13.HGV is a DNA virus
14.HGV interfere with HIV replication
15.Anti-HBsAg is not detectable in chronic HBV infe ction
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64. Reference
•Review of Medical Microbiologyand Immunology. Warren Levinson,
12
th
May 2012. Mc Graw-Hill(Lange)
•Jawetz, Melnickand Adelberg’sMedical Microbiology
George F. Brooks, Karen C. Carroll, Janet S. Butel,
25
th
Mar 2010. Mc Graw-Hill(Lange)
•Bailey and Scott’sDiagnostic Microbiology.Betty A.Forbes,
Daniel F. Sahm, Alice S. Weissfeld,12
th
2007.Mosby Elsevier
•Lippincott’s illustrated review Microbiology . Richard A Harvey,
PamellaC. Champe, Bruce D. Fisher, 2007. Lippincott William &
Wilkins
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