The carboxyl-terminal domain of large T antigen rescues SV40 host range activity in trans independent of acetylation

The host range activity of SV40 has been described as the inability of mutant viruses with deletions in the C terminal region of large T Ag to replicate in certain types of African green monkey kidney cells. We constructed new mutant viruses expressing truncated T Ag proteins and found that these mutant viruses exhibited the host range phenotype. The host range phenotype was independent of acetylation of T Ag at lysine 697. Co-expression of the C terminal domain of T Ag (aa 627-708) in trans increased both T Ag and VP1 mRNA as well as protein levels for host range mutant viruses in the restrictive cell type. In addition, the T Ag 627-708 fragment promoted the productive lytic infection of host range mutant viruses in the nonpermissive cell type. The carboxyl-terminal region of T Ag contains a biological function essential for the SV40 viral life cycle.