Immunization with whole inactivated vaccine protects from infection by SIV grown in human but not macaque cells.

Homologous SIVsm stocks were generated by passage of a macaque isolate of SIVsm (SIVsm/E660) in human CEM x 174 cells or macaque peripheral blood mononuclear cells. Macaques were immunized with whole inactivated SIV vaccine consisting of virus generated by transfection of CEM x 174 cells with the SIVsmH4 clone and were challenged with either cell-free stock. Only vaccinees challenged with virus generated in human cells were protected from infection. This confirms the species-specificity of whole inactivated vaccine-mediated protection.