Hepatitis A virus antibodies

Clinical significance
HAV belongs to the picornavirus family and has an RNA genome. Hepatitis A is transmitted by the faecal-oral route, mainly through contaminated food (especially raw shellfish) or water. The hepatitis A virus replicates in the liver, is excreted in the bile and eliminated in the stool. The incubation period averages 4 weeks. The infection is self-limiting, does not become chronic and may be asymptomatic, especially in children. When present, symptoms include an enlarged liver, jaundice, dark urine, weakness, nausea, vomiting and abdominal pain. Antibodies against HAV can be detected from the onset of symptoms of the infection. The initial antibody response is mainly limited to the IgM subclass. Anti-HAV IgM antibodies are usually detectable for 3-6 months after the onset of illness, while anti-HAV IgG may persist indefinitely. Specific anti-HAV IgM is the most useful serological marker for diagnosing acute HAV infection. Total anti-HAV is used mainly to detect previous exposure to the hepatitis A virus and to confirm immunity after vaccination.