Hepatitis b virus

for microbiology

1. HEPATITIS B VIRUS MAN BAHADUR RANA BPH,ACAS,NEPAL

2. Introduction

3. History

4. Morphology

5. - HBV is a complex 42 nm double shelled particle. - The outer surface or envelope of virus contains Hepatitis B surface antigen ( HBsAg). - It encloses an inner icosahedral 27nm nucleocapsid (core), which contain hepatitis B core antigen (HBcAg). - Inside the core is the genome, a circular double stranded DNA and a DNA polymerase. Contd….

6. 1. HBsAg: - Surface antigens (envelope protein). - It is made up of lipid, protein and carbohydrate. 2. HBcAg : - It is the core(nucleocapsid) antigen of the virus - It is not detectable in patients blood. Antigenic structure

7. 3. HBeAg: - It appears in serum along with HBsAg but disappears within a few weeks. - HBcAg and HBeAg though immunologically distinct are coded by the same gene. Contd…

8. There are three important modes of transmission of HBV infection. 1. Parenteral 2. Perinatal 3. Sexual Parenteral: - Transmission of infection may result from accidental inoculation of minute amounts of blood, blood products or fluid containing HBV during medical, surgical or dental procedure. Mode of Transmission

9. - Needlestick injuries, use of contaminated needles and syringes, intravenous and percutaneous drug abuse, ear and nose piercing, tattooing, acupuncture, sharing of shaving razor and kissing can transmit HBV infection. Perinatal: - Transmission probably occurs when carrier mothers blood contaminates the mucous membranes of the new born during birth. Contd…

10. Sexual Transmission: - HBV is present in body fluids such as semen and vaginal secretions, hence it can be transmitted by sexual contact. - Male homosexual are at higher risk of acquiring infection. Contd…

11. Clinical features: - The incubation period varies from 6 weeks to 6 months. - The course of acute HBV infection can be divided into three phase. . Pre-ecteric . Icteric . Convalescent Contd…

12. Pre-icteric phase: In this phase patient develops malaise, anorexia, weakness, nausea and vomiting Icteric phase: Patient develops jaundice, pale stools, and dark urine.(bilirubinuria). Convalescent phase: This phase is long and drawn out with malaise and fatigue. Contd..

13. 1. Laboratory diagnosis of HBV infection can be carried out by detection of hepatitis B antigen and antibodies. These can be detected by sensitive and specific tests like ELISA and RIA. 2. Viral DNA Polymerase: It appears transiently in serum during pre-icteric phase. Laboratory Diagnosis

14. 3. Polymerase chain infection: HBV DNA level can be detected in serum by PCR . It is a highly sensitive test. Biochemical test: - SGPT and SGOT level increases - Serum bilirubin level indicates the degree of jaundice and may rise up to 25 fold. Contd…

15. - General Preventive Measure - Immunisation General Preventive Measure: These include health education , improvement of personal hygiene. Use of unsterile needle, syringes and other material must be avoided to prevent hepatitis B infection. Prophylaxis

16. i ) Passive immunization: - Passive immunization may be employed following any accidental exposure to hepatitis B infection. - It can be given in doses of 300-500 IU intramuscularly. - Vaccine should be administered as early as possible after exposure, preferably with in 48 hours. - A second dose is given at an interval of 4 weeks, after the first dose. Immunization

17. - It may not prevent infection but protect against illness and the development of carrier state. ii) Active immunization: Following vaccines are available a) Plasma derived vaccine b) Recombinant yeast hepatitis B Vaccine. Contd…

18. a) Plasma derived vaccine: - It consist of purified 22nm particles of HBsAg, prepared from the plasma of symptomless carriers. - The particles are seperated by ultracentrifugation and treated with proteinase, 8M urea and formaldehyde. - This vaccine is still being produced and used particularly in developing countries where the need is greatest. Contd…

19. b) Recombinant yeast hepatitis B Vaccine: It is produced by cloning the HBsAg gene in yeast Saccharomyces cerevisae and the HBsAg particles produced are extracted and purified for use as vaccine. This vaccine is safe, antigenic, free from side effects and as immunogenic as plasma derived vaccine. Contd…