Inactivation of hepatitis B virus and non-A, non-B hepatitis by chloroform

To determine whether a non-A, non-B hepatitis agent contained essential lipids, we extracted with chloroform a dilution of human plasma that contained approximately 10(4) chimpanzee infectious doses of non-A, non-B hepatitis virus and then tested for infectivity in chimpanzees. In addition, we treated a serum containing hepatitis B virus in the same way. Both of these samples were also sham extracted as controls. Known chloroform-sensitive and chloroform-resistant viruses were added directly to the hepatitis-containing serum or plasma as internal controls or to fetal calf serum as external controls and were assayed for infectivity in vitro after chloroform extraction or sham extraction. All infectivity of the diluted plasma that contained at least 10(4) chimpanzee infective doses of non-A, non-B hepatitis agent and all infectivity of the serum that contained 10(3.5) chimpanzee infective doses of hepatitis B virus were destroyed by chloroform. The chloroform-sensitive control viruses were completely inactivated, but the chloroform-resistant control viruses lost less than 0.5 log10 of infectivity. Sham-extracted non-A, non-B hepatitis agent-containing plasma was shown to maintain its infectivity in chimpanzees that had initially been inoculated with the chloroform-extracted plasma. Thus, both hepatitis type B and non-A, non-B hepatitis appear to be caused by viruses that can be inactivated by a lipid solvent.