Studies of Prototype Live Hepatitis A Virus Vaccines in Primate Models

Abstract

We have prepared two prototype live hepatitis A virus (HAV) vaccines by serial passage of the HM-175 strain of HAV in African green monkey kidney cells. Passage 21 (P-21) HM-175 virus shows evidence of attentuation for chimpanzees but not for marmosets; passage 32 (P-32) HM-175 virus shows evidence of attenuation for both species. Animals that received P-32 HAV had fewer elevations in levels of liver enzyme activity and evidence of less virus replication in the liver and excretion of virus in stool than did those that received wild-type virus. The P-21 and P-32 viruses were highly immunogenic in both species. The information provided by this study will aid in the development of a live HAV vaccine.