Figure 3.

SV40 internalization is inhibited at 20°C. Vero cells were infected with SV40 for 4 h at either 20 or 37°C before neutralizing surface-exposed virus with SV40 neutralizing antiserum. After subsequent incubation at 37°C for a remaining 24 h, the cells were fixed and immunolabeled for T-ag. Quantitation of infection efficiency revealed a much greater sensitivity of the virus to the neutralizing antibody after infection at 20°C than after infection at 37°C. Infection efficiencies are shown normalized to controls not exposed to the neutralizing antiserum. A representative experiment is shown.