Attempts to differential hepatitis B from hepatitis A infection by newly developed serological tests.

An immune Indian ink micro-agglutination method has been evolved for the detection of an antigen present in the blood associated with infectious hepatitis (called IHxAg). In previous studies 86% of serum samples taken from children with hepatitis A proved to be positive by this technique. Present studies were related to 239 adult in-patients with a clinical diagnosis of hepatitis A (123 cases) or hepatitis B (116 cases). Blood samples taken serially during the illness were tested for IHxAg, HBsAg and anti-HBsAg. The results were in accordance with the clinical diagnosis in 60% in contradiction in 30%, whilst all tests brought negative results in 10%. The clinical laboratory findings (SGPT, thymol turbidity) were more in harmony with our laboratory results than with the clinical diagnoses. Rheumatoid factor did not disturb the immune Indian ink reaction, labile serum proteins caused, however, non-specific reaction in 30% of serum samples. When durocytes were used instead of Indian ink the rate of false positive results dropped to 10%. Sera taken in convalescent phase from patients with IHx antigenemia in the acute phase of illness contained an antibody against IHxAg. A crude gammaglobulin preparation from a pool of convalescent sera gave a precipitation line in agarose gel with an antigen present in the fecal extract of children with hepatitis A. This precipitation line proved to contain virus-like particles with an approximate diameter of 25 nm when tested by electronmicroscopy. No precipitation could be seen when sera of the same patients were tested against the same gammaglobulin preparation.