Susceptibility to superinfection of simian cells transformed by SV40

Abstract

Characterization of a stable line of African green monkey kidney cells (BSC-1) transformed by SV40 was undertaken to determine whether these cells were resistant to superinfection by the homologous virus. The transformed cells were shown to synthesize the SV40-specific tumor antigen, the surface antigen, and the transplantation rejection antigen; SV40 capsid antigen was not detected. Infectious SV40 could not be recovered even after fusion of the transformed cells with cells susceptible to SV40 replication. Human adenovirus types 2, 7, and 12 replicated in the cells (but not in the parental, nontransformed cells), indicating either that the portion of the SV40 genome which aids the replication of human adenoviruses in simian cells was present in the transformed cells or that an adenovirus-sensitive cell population had been selected. However, SV40 was unable to replicate in the transformed cells, although simian adenovirus 7 and herpes viruses types 1 and 2 replicated in both parental and transformed cells. A defective SV40 genome encapsidated in an adenovirus coat (PARA particle) was used to further analyze the ability of the transformed cell to replicate the superinfecting SV40 genome. Since replication of PARA particles occurred, a defective SV40 genome can be replicated in an SV40-transformed cell. Unresolved is the question concerning expression of late virus functions in these cells as PARA is defective in the ability to induce the synthesis of SV40 capsid protein.