Identification of immunodominant Th1-type T cell epitopes from Schistosoma japonicum 28 kDa glutathione-S-transferase, a vaccine candidate.
Th1-type cytokines produced by the stimulation of Th1-type epitopes derived from defined schistosome-associated antigens are correlated with the development of resistance to the parasite infection. Schistosoma mansoni 28 kDa glutathione-S-transferase (Sm28GST), a major detoxification enzyme, has been recognized as a vaccine candidate and a phase II clinical trial has been carried out. Sheep immunized with recombinant Schistosoma japonicum 28GST (Sj28GST) have shown immune protection against the parasite infection. In the present study, six candidate peptides (P1, P2, P3, P4, P7 and P8) from Sj28GST were predicted, using software, to be T cell epitopes, and peptides P5 and P6 were designed by extending five amino acids at the N-terminal and C-terminal of P1, respectively. The peptide 190-211 aa in Sj28GST corresponding to the Th1-type epitope (190-211 aa) identified from Sm28GST was selected and named P9. The nine candidate peptides were synthesized or produced as the fusion protein with thioredoxin in the pET32c(+)/BL21(DE3) system. Their capacity to induce a Th1-type response in vitro was measured using lymphocyte proliferation, cytokine detection experiments and flow cytometry. The results showed that P6 (73-86 aa) generated the strongest stimulation effect on T cells among the nine candidate peptides, and drove the highest level of IFN-gamma and IL-2. Therefore, P6 is a functional Th1-type T cell epitope that is different from that in Sm28GST, and will be useful for the development of effective vaccines which can trigger acquired immunity against S. japonicum. Moreover, our strategy of identifying the Th1-type epitope by a combination of software prediction and experimental confirmation provides a convenient and cost-saving alternative approach to previous methods.
Li
Guang-Fu
GF
Department of Pathogenic Biology, Nanjing Medical University, Nanjing 210029, China.
Wang
Yong
Y
Zhang
Zhao-Song
ZS
Wang
Xin-Jun
XJ
Ji
Min-Jun
MJ
Zhu
Xiang
X
Liu
Feng
F
Cai
Xiao-Ping
XP
Wu
Hai-Wei
HW
Wu
Guan-Ling
GL
D000595:Amino Acid Sequence; D000818:Animals; D005260:Female; D005982:Glutathione Transferase / Q000737:chemistry* / Q000276:immunology / Q000627:therapeutic use*; D016056:Immunodominant Epitopes / Q000276:immunology / Q000627:therapeutic use; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D012549:Schistosoma japonicum / Q000378:metabolism*; D012554:Schistosomiasis japonica / Q000276:immunology / Q000517:prevention & control*; D012908:Snails; D018417:Th1 Cells / Q000276:immunology*; D016896:Treatment Outcome; D022282:Vaccines, Acellular / Q000276:immunology / Q000627:therapeutic use*
D016056:Immunodominant Epitopes; D022282:Vaccines, Acellular; D005982:Glutathione Transferase