To examine the mechanism of immunity in vivo, researchers used poliovirus receptor-transgenic mice on a BALB/c (H-2d) background. Mice immunized with the vaccine strain were protected against a subsequent challenge with wild-type virus. Protection was observed when mice received primed B cells in the presence of a VP4-specific Th1 clone. Findings demonstrate that CD4+ T cells, specific for the internal poliovirus capsid protein, VP4, can provide effective help for a protective antibody response directed against surface capsid proteins (Mahon et al., 1995).
