IDentification of helper T cell epitopes of dengue virus E-protein

The T cell proliferative response to dengue 2 (Jamaica) E-glycoprotein (495 amino acids) was analyzed in vitro using either killed virus or E-protein fragments or synthetic peptides. Inactivated dengue virus stimulated dengue-specific lymph node (LN) CD4 + T cell proliferation in BALB/c (H-2 d ), C3H (H-2 k ) and DBA/1 (H-2 q ) but not in C57BL/6 (H-2 b ) mice. Moreover, LN cells from dengue-virus primed BALB/c mice proliferated in vitro in response to three purified non-overlapping E-protein fragments expressed in E. coli as polypeptides fused to trpE (f22–205, f267–354, f366–424). To further determine T cell epitopes in the E-protein, synthetic peptides were selected using prediction algorithms for T cell epitopes. Highest proliferative responses were obtained after in vitro exposure of virus-primed LN cells to peptides p135–157, p270–298, p295–307 and p337–359. Peptide p59–78 was able to induce specific B and T cell responses in peptide-primed mice of H-2 d, H-2 q and H-2 k haplotypes. Two peptides p59–78 corresponding to two dengue (Jamaica and Sri Lanka) isolates and differing only at position 71 cross-reacted at the B but not at the T cell level in H-2 b mice. This analysis of murine T helper cell response to dengue E-protein may be of use in dengue subunit vaccine design.