Infectivity of HBV is indicated by -

Ans. is 'a' i.e., HBeAg HBeAg - Infectivity - Active multiplication Serologic and virologic markers of HBV infection 1. HBsAg o First virological marker detectable in the serum o HBsAg presence precedes elevations of serum aminotransferase activity and the onset of clinical illness, o HBsAg become undetectable 1-2 months after the onset of jaundice and rarely persists beyond 6 months, o In chronic HBV infection, HBsAg remains detectable beyond 6 months. 2. HBcAg o It is not demonstrable in the circulation because it is enclosed within the HBs Ag coat, o HBc Ag remains in the hepatocyte, where it can readily be detectable by immunohistochemical staining. 3. HBeAg o HBe Ag appears concurrently with or shortly after HBs Ag. o HBe Ag is an indicator of active intrahepatic replication and high injectivity. o It is a qualitative marker of HBV replication. o HBsAg carrier mothers who are HBeAg positive almost invariably (> 90%) transmit hepatitis B infection to their offspring, whereas HBsAg carrier mothers with anti HBe rarely (10 to 15%) infect their offspring. o HBe testing is indicated primarily during follow up of chronic infection. 4. Anti HBeAg o Appears within the first I to 2 weeks after the appearance of HBs Ag. o In acute or recent infection IgM anti-HBc is detected, o IgG anti-HBc indicates remote infection. 5. Anti HBsAg o It becomes detectable in blood when HBs Ag disappears, o Anti HBs Ag is a protective antibody. o It is the only serological marker; present after immunization. 6. Anti HBeAg o The disappearance of HBe Ag is followed by the appearance of anti-HBe Ag. o Its presence indicates low infectivity and virus replication. 7. HBVDNA o It is the quantitative marker of virus replication. Remember o For the diagnosis of HBV infection, detection of HBs Ag in blood is all that ordinarily necessary. o The simultaneous presence of IgM anti-HBc indicates recent infection, while IgG anti-HBc indicates remote infection. o In 1-5% of patients, there is a "window" or ''gap" period between the disappearance of HBs Ag and appearance of anti-HBs Ag. During this period diagnosis is made by lgM anti-HBc Ag.