Biology of simian virus 40 (SV40) transplantation antigen (TrAg) III. Involvement of SV40 gene A in the expression of TrAg in permissive cells.

Temperature-sensitive (ts) mutants of simian virus (SV40) which map in the early region of the SV40 genome were used to determine the role of the viral genome in the expression of SV40-specific transplantation rejection antigen (TrAg). The results indicated that tsA mutants (1612, 1637, 7, and 28) did not induce the expression of SV40-TrAg at the surface of infected permissive African green monkey kidney cells (TC-7) at 41° but did induce the expression of TrAg at the permissive temperature (33°) in TC-7 cells. Wild-type SV40 and late SV40 temperature-sensitive mutants (tsBC1602, tsBC1606, tsB8, and tsC219) induced SV40-TrAg in TC-7 cells at nonpermissive and permissive temperatures with equal efficiency. One of the mutants belonging to complementation group D (tsD1601) was defective in inducing SV40-TrAg at 41°. Kinetic studies indicated that SV40-TrAg appears by 18 hr after infection at 41° and 38 hr post-infection at 33°, paralleling closely the synthesis of T antigen. The synthesis of immunoreactive T antigen in TC-7 cells infected with tsA mutants at nonpermissive temperature did not correlate with the inability of tsA mutants to express TrAg at nonpermissive temperature. We conclude that the expression of TrAg in SV40-infected cells depends upon normal functioning of the A gene.