Prediction and screening of cytotoxic T-lymphocyte epitopes targeting human papillomavirus 16 E6 and E7 oncoproteins
Objective Using human papillomavirus 16(HPV16)E6 and E7 oncoproteins as target antigens,to predict and screen cytotoxic T lymphocyte(CTL)-dominant epitopes that can be co-presented by human and murine major histocom-patibility complex(MHC)molecules by bioinformatics methods and validated in mice.Methods The oncoproteins se-quences of HPV16 E6 and E7 were obtained from the National Center for Biotechnology Information(NCBI)website,and the CTL epitopes of human leukocyte antigen(HLA)-A*02:01,HLA-A*11:01,HLA-A*24:02 restriction and C57BL/6 mouse H-2b restriction were predicted by the MHC-Ⅰ processing and MHC-Ⅰ binding methods in the Immune Epitope Database(IEDB)website,and then screened for co-presentation of both based on the scores.A DNA vaccine ex-pressing HPV16 E6 and E7(pVAX1-E6E7Com)was also constructed,and splenic lymphocytes were isolated after im-munisation of mice.The predicted CTL epitopes obtained were used as antigens,and the ability of each CTL epitope to induce specific T cell immune responses was assessed by enzyme linked immunospot assay after co-cultivation with mouse splenic lymphocytes for 40 hours.The experimental data were compared between groups by one-way ANOVA and Dun-nett t test.Results Ten CTL antigenic epitopes co-presented by human and murine MHC molecules were predicted and screened.The enzyme-linked immunospot assay results showed that each peptide in the experimental group induced spe-cific immune responses in mouse lymphocytes.The difference of each peptide in the experimental group was not statisti-cally significant(P＞0.05)compared with the positive reference peptide(E7-49 RAHYNIVTF57).Compared with the positive reference peptide(156.20±97.40),E6-38 VYCKQQLL45(175.60±52.88),E6-49 VYDFAFRDL57(202.20±108.50),E6-86 YCYSLYGTTL95(157.00±44.46),and E7-77RTLEDLLMGTL87(162.20±49.35)elicited a higher num-ber of specific spots.Conclusion All 10 CTL epitopes predicted and screened by this bioinformatics approach are immu-nogenic and can be advantageous candidate epitopes for HPV type 16 therapeutic vaccines.
human papillomavirus type 16(HPV16)E6E7cytotoxic T lymphocyte epitopes
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