Serum IgA anti-hepatitis A virus as detected by enzyme-linked immunosorbent assay. Diagnostic significance in patients with acute and protracted hepatitis A.

A capture enzyme-linked immunosorbent assay for the detection of serum IgA against hepatitis A virus has been developed. The test was highly specific, and the time course of detectability of IgA anti-HAV was longer than six months in 42/42 patients with acute or protracted hepatitis A followed prospectively, but shorter than two years in 14/14 patients tested 21-24 months after diagnosis of acute hepatitis A. IgM anti-HAV were at detectable levels in only 1/42 cases tested six months after the clinical onset. The detection of serum IgA anti-HAV is a simple and specific method to differentiate protracted cases of hepatitis A from non-A, non-B hepatitis.