Non-A, non-B (type 1) hepatitis agent capable of inducing tubular ultrastructures in the hepatocyte cytoplasm of chimpanzees: inactivation by formalin and heat.

We have reported two kinds of viruslike particles derived from human sera that induced morphologically and serologically different types of non-A, non-B hepatitis in chimpanzees. A chimp serum containing one such agent capable of inducing a type of hepatitis with cytoplasmic tubular ultrastructures (non-A, non-B, type 1) was titrated for its infectivity in chimps. Two chimps who received 1 ml of a 10(-2) dilution of the original serum developed the characteristic morphological changes in the liver together with elevated serum transaminase levels, while the other two who received 1 ml of a 10(-4) dilution failed to show such changes. The two who escaped the infection were proven to be susceptible to the agent, because they developed non-A, non-B, type 1 hepatitis when they were challenged by 1 ml of a 10(-1) dilution of the same serum on the 23rd week after the first inoculation. One milliliter of a 10(-1) dilution containing more than 10 chimp infecting units were inactivated in the presence of 1/2000 formalin or by heating at 100 degrees C for 5 min and then given to four other chimps. None of them developed clinical or histologic evidence of non-A, non-B, type 1 hepatitis, thereby indicating that both formalin and heat could destroy the ability of the agent to induce this type of hepatitis.