Methods of Protection Against Homologous Serum Hepatitis

Antigenic differences between certain strains of infectious (epidemic) hepatitis virus (IH) of relatively short incubation (about eighteen to forty days) and certain strains of serum hepatitis virus (SH) of relatively long incubation (about sixty to one hundred and fifty days) 1 have been conclusively demonstrated. The data of Oliphant, 2 suggesting immunologic similarities in such viruses, could well be explained by the facts that: (1) the virus, designated by Oliphant as that of epidemic hepatitis, had a long incubation period (about seventy-five days), (2) thus, it actually may have been a strain of serum hepatitis virus, SH, rather than one of epidemic hepatitis, IH, and (3) a cross immunity with his designated serum hepatitis virus, SH, therefore would not have been surprising. The confusion concerning the origin of such strains of hepatitis virus can best be clarified by study of their immunologic behavior in experimental subjects. It thus would appear