SEROLOGY OF HEPATITIS B:-
● Considered to be infected ( can be acute/chronic or carriers)
● Persistence of HBsAg is used to differentiate acute from chronic infection.
●Presence of the antigen longer than 6 months after initial exposure indicates chronic infection.
● Epidemiological marker.
● Implies either active or passive immunization that usually persists for life.
■ (NOTE:- HbcAg is not detectable in serum)
● first detectable antibody
● IgM anti-HBc indicates acute infection.( most reliable and earliest marker of acute hepatitis infection).
● Only serologic marker detectable during the “window period “ .
● IgG anti-HBc indicates previous or ongoing infection.
● High infectivity and active disease.
● Higher rates of viral transmission.
● Marker of viral replication and infectivity. ( HbeAg----produced only during replication of the virus)
● It indicates “low infectivity.”
● Loss of HBeAg and appearance of anti-HBe in serum is called “seroconversion”
● Indicates clinical improvement (=remission of the disease).
- HBV DNA (quantitative viral load)
● It indicates viral burden and viral replication.
● Assess recovery from infection and candidacy for antiviral therapy.
● To differentiate between inactive carrier state and chronic active hepatitis in chronic HBV infection.
A) Imp info :-
Qualitative marker of HBV-replication-----HbeAg.
Quantitative marker of HBV-replication:-
Definitive is HBV-DNA >HBV-DNA polymerase
■ Earliest marker of infection ------HBsAg.
■Earliest marker of “Acute Infection”----IgM anti-HBc.
■ "INACTIVE CARRIERS ":-
● Refers to HBeAg-negative with normal serum ALT levels and low (< 2000 IU/mL) or undetectable HBV DNA.
■ Precore or Basic core mutant HBV:-
● Also referred to as HBeAg-negative, or anti-HBe-positive HBV.
● HBeAg-negative and anti-HBe-positive patients with high serum HBV-DNA levels (>10000 copies /ml) and persistent or intermittent elevations in alanine aminotransferase (ALT) activity.
● It represents severe and progressive form of liver disease.
● It is associated with frequent development of cirrhosis and HCC.
■ " Hepatitis B “Super carrier” :-
● High titres of HBsAg and HBV-DNA in blood along with HBeAg.
● It indicates early stage of carrier and “highly infectious”.
■ " Hepatitis B “Simple carrier” :-
● Low titre of HBsAg , anti HBe positive, and HBV-DNA negative.
● It indicates late stage of carrier and they will transmit infection when large quantities of blood are transferred.