Serodiagnosis of Viral Hepatitis A by a Solid-phase Radioimmunoassay Specific for IgM Antibodies

Abstract

A solid-phase radioimmunoassay for detecting specific IgM antibodies to hepatitis A virus (HAV) was developed and characterized. The test utilized microtiter plates coated with anti-IgM to specifically absorb the IgM antibodies from the test serum. The anti-hepatitis A IgM antibodies are measured by the specific consecutive binding of hepatitis A antigen and radiolabelled anti-hepatitis A antibodies (anti-HA). In 6 chimpanzees infected with HAV, IgM anti-HA was detected from about the first date of elevated transaminases and was positive for about 3 months. The usefulness of the test was confirmed by testing acute phase sera of 30 patients from a common source outbreak of epidemic hepatitis, and negative sera from 2 control groups. A collection of serum specimens from 190 patients with sporadic HBsAg-negative hepatitis in Brazil was also tested and an etiologic association with HAV was confirmed in the majority of these cases.