Question
To determine the endemicity of disease caused by an organism shown in photograph below, what should be measured?
A. HBsAg.
B. HBcAg.
C. HBeAg.
D. Anti-HBeAg.
Show Answer
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Correct Answer » A Explanation |
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Ans: A. HbsAg.
Image shown is of Hepatits B virus.
Hepatitis B virus
- Hepatitis B virus (HBV) is a member of the hepadnavirus family.
- The virus particle (virion) consists of an outer lipid envelope and an icosahedral nucleocapsid core
- The genome of HBV is made of circular DNA, but it is unusual because the DNA is not fully double-stranded.
Antigens :
- Hepatitis B surface antigen (HBsAg)
- Hepatitis B core antigen (HBcAg)
- Hepatitis B viral protein(HBeAg).
HBsAg testing is widely used as a marker of HBV infection in epidemiological surveys.
Serological markers for HBV
Serological markers for HBV infection are :‑
- HBs Ag (surface antigen or Australia antigen) : It is the first marker which appears in the serum. It is the epidemiological marker for HBV infection.
- HBc Ag (core antigen) : It is not demonstrable in serum because it is enclosed by HBsAg coat.
- HBe Ag (envelope antigen) : It is marker of active replication and high infectivity. It is qualitative marker of replication. HBs Ag carrier mothers who are HBe Ag positive almost invariably (> 90%) transmit hepatitis B infection to their offspring, where as HBs Ag carrier mothers with anti HBe rarely (10 to 15%) infect their offspring.
- Anti-HBc Ag : It is the first antibody appears in serum. IgM anti-HBc Ag is a marker of acute or recent infection. IgG anti-HBc Ag indicates remote infection.
- Anti-HBs Ag : It is protective antibody. It is the only serological marker present after vaccination. After an infection, its presence indicates recovery and end of period of communicability.
- Anti-HBe Ag : Its presence indicate stopage of replication and low infectivity.
- HBV DNA : It is quantitative marker of HBV replication.
