A helper T-cell epitope of the E7 protein of human papillomavirus type 16 in BALB/c mice

The helper T-cell response to the E7 protein of human papillomavirus type 16 (HPV16) was studied using BALB/c (H-2d) mice. Twenty-two overlapping synthetic peptides spanning the HPV16 E7 protein were split into 6 groups. Mice were sensitized using mixtures of synthetic peptides corresponding to each of the groups. Lymph node cell suspensions were cultured with the corresponding mixture of synthetic peptides that was used for sensitization. Two mixtures induced a proliferative response. Analysis of the individual peptides from these mixtures showed that two (overlapping) peptides induced a proliferative response. This response was mediated by CD4 + cells. The common region of the two peptides was found to be a single epitope, and a minimal epitope was demonstrated (AHYNIVTFCCK). In conclusion, in contrast to others, we demonstrated a helper T-cell response in BALB/c mice. This may be due to the fact that we used synthetic peptides as immunizing agent. The helper T-cell epitopes in HPV16 E7 demonstrated previously are partly overlapping with the (minimal) epitope demonstrated here, underlining the ‘public’ nature of the epitope.