FIG 5.

Replication of a BFA-resistant virus can be rescued in Vero cells by expression of exogenous GBF1. (A) Scheme of GBF1 protein with Vero cell-specific amino acid substitutions indicated. (B) GBF1 with Vero cell-specific mutations is fully functional in supporting poliovirus replication. HeLa cells were transfected with plasmids expressing either human or Vero cell-specific GBF1s with BFA-resistant mutation A795E in the Sec7 domain. Replication of the wt poliovirus replicon was assessed in these cells in the presence or the absence of BFA. The expression of the exogenous GBF1 species is shown. (C) Replication of the DM BFA-resistant mutant poliovirus (G4361A + C5190T) is rescued in Vero cells expressing exogenous GBF1 (arrow). A low level of replication was observed in nontransfected cells (arrowheads). (D) Selection of BFA-resistant mutants in Vero cells starting from the DM BFA-resistant mutant poliovirus (G4361A + C5190T) was not successful. The virus yield was determined by titration on the HeLa cell monolayer of the material from passages 2 (P2) and 10 (P10). The control shows replication of the DM mutant on Vero cells in the absence of BFA. The P value is shown; the difference between titers from passages 2 and 10 was not statistically significant (NS).