Antigenic Sequences of Poliovirus Recognized by T Cells: Serotype-Specific Epitopes on VP1 and VP3 and Cross-Reactive Epitopes
on VP4 Defined by Using CD4+ T-Cell Clones
A panel of poliovirus-specific murine CD4+ T-cell clones has been established from both BALB/c (H-2d) and
CBA (H-2k) mice immunized with Sabin vaccine strains of poliovirus serotype 1, 2, or 3. T-cell clones were
found to be either serotype specific or cross-reactive between two or all three serotypes. Specificity analysis
against purified poliovirus proteins demonstrated that T-cell clones recognized determinants on the surface
capsid proteins VP1, VP2, and VP3 and the internal capsid protein VP4. Panels of overlapping synthetic
peptides were used to identify eight distinct T-cell epitopes. One type 3-specific T-cell clone recognized an
epitope within amino acids 257 and 264 of VP1. Three T-cell epitopes corresponding to residues 14 to 28, 189
to 203, and 196 to 210 were identified on VP3 of poliovirus type 2. The remaining four T-cell epitopes were
mapped to an immunodominant region of VP4, encompassed within residues 6 and 35 and recognized by both
H-2Z and H-2k mice. The epitopes on VP4 were conserved between serotypes, and this may account for the
predominantly cross-reactive poliovirus-specific T-cell response observed with polyclonal T-cell populations. In
contrast, T-cell clones that recognize epitopes on VP1 or VP3 were largely serotype specific; single or multiple
amino acid substitutions were found to be critical for T-cell recognition
