Progress toward a Live, Attenuated Human Hepatitis A Vaccine

Abstract

Human hepatitis A virus was attenuated in virulence for marmosets by passage in FRhK6 and human diploid lung fibroblast cell cultures. A number of variants were produced that showed different levels of virulence/attenuation for marmosets. Marmosets that had attenuated virus-like responses following injection of variant virus were challenged with virulent virus; all were solidly immune to infection. Antibody stimulated by the vaccine equated with protection. These findings show that human hepatitis A virus can be attenuated and show the feasibility for eventual development of a live, attenuated hepatitis A vaccine for human use.