Review of infectivity studies in nonhuman primates with virus-like particles associated with MS-1 hepatitis.

Using the technique of immune electron microscopy we have conducted hepatitis A infectivity studies in marmoset monkeys and chimpanzees. Marmosets inoculated with human serum containing the MS-1 strain of hepatitis A virus have developed hepatitis and seroconverted to 27 nm virus-like particles isolated from stools of humans in the early acute stages of hepatitis. Similar results have been observed through several marmoset subpassages, and the virus-like particles have been recovered from the liver of animals in the acute phase of hepatitis. Chimpanzees inoculated with stool filtrates containing the virus-like particles develop hepatitis with concomitant excretion of the particles in early acute phase stools and subsequent development of serum antibody to the particles. These studies provide evidence that the above particles constitute the virus of hepatitis A of the MS-1 prototype.