Hepatitis A antibody is a specific antibody against hepatitis A. hepatitis A virus (HAV) is an icosahedral stereosymmetric spherical particle with a diameter of 27-32nm and no envelope, with a single stranded positive strand RNA at its core. HAV belongs to the small RNA virus family hepatovirus or heparnavirus. HAV is mainly transmitted through the hand-oral route, and the incubation period is 15-50 days, with an average of 28 days. The virus is often present in the blood and stool of patients 5 to 6 days before the elevation of serum ALT. 2-3 weeks after onset, the infectivity of serum and stool gradually disappears with the production of specific antibodies in the serum. Laboratory diagnosis of HAV can be performed with antibody testing. The most commonly used method in clinical practice is to detect anti-HAV antibodies by ELISA.

IgM positive HAV antibody is found in patients with hepatitis A. Serum anti-HAV IgM antibody is the marker of HAV acute infection, which appears in the early stage of infection and is the basis for early diagnosis of hepatitis A. High titers were maintained for 3 months after infection and gradually disappeared after 6 months. The common methods of anti-HAVIGM detection include enzyme-linked immunosorbent assay (ELISA) and solid phase radioimmunoassay (SPRIA), which have high sensitivity and strong specificity, and are routine items for acute hepatitis patients. Rheumatoid factor positive specimens can appear false positive anti-HAVIGM, should be noticed. If low titers are detected, the test should be repeated every 2 weeks, but attention should be paid to false positives caused by rheumatoid factors.

ELISA method (1) Hepatitis A antibody immunoglobulin M(anti-HaVIGM) : negative (2) Hepatitis A antibody immunoglobulin G(anti-HavigG) : negative