Detection of hepatitis A virus proteins in infected BS-C-1 cells

Hepatitis A virus (HAV) is distinguished from other picornaviruses by its tropism for the liver in infected hosts, a nonlytic infection in hepatocytes, and a slow and nonlytic growth cycle in cultured cells. Although the genome structure and organization of HAV appear to be similar to those of the other picornaviruses, the viral proteins synthesized in infected cells have not been previously characterized. We have utilized specific antisera raised in rabbits to recombinant HAV proteins expressed in Escherichia coli in an effort to identify both structural and nonstructural proteins in BS-C-1 cells throughout the course of a viral replication cycle. Replication was monitored by dot blot hybridization of viral genomes. Structural proteins VP0, VP1, VP2, and VP3 were found to accumulate during the infection cycle as did viral RNA. Nonstructural proteins 2C and 3D were not detected on immunoblots, although a minor amount of 2C could be detected by immunoprecipitation of lysates of radiolabeled, infected cells. The relative sensitivities of the various antisera were determined, and the failure to observe nonstructural proteins was shown not to be due to decreased sensitivity of the detection reagents. Thus, it appears that HAV nonstructural proteins do not accumulate in infected cells to levels comparable to those of capsid proteins.