近期研究表明，基于肽的疫苗在癌症免疫治疗中具有强效的疗效。通过同时将佐剂和抗原肽分子共同运送到抗原呈递细胞，免疫学性能得到了优化。在我们之前的研究中，我们展示了一个由40-mer CpG-DNA和一个抗原卵清蛋白肽构成的结合物，通过二硫键结合有效地诱导了体内卵清蛋白特异性细胞毒性T淋巴细胞（CTL）反应。在本研究中，基于这个结合设计，我们制备了一个由30-mer CpG-DNA（CpG30）和一种癌症抗原性的酪氨酸酶相关蛋白2的肽（TRP2180-188）组成的结合物，其中TRP2180-188的N-末端附着有一个半胱氨酸残基。然而，用这个结合物免疫小鼠并没有诱导出有效的TRP2180-188特异性免疫反应。考虑到结合物中产生的肽（10-mer）可能过长，无法适应H-2Kb分子的结合，因为最佳结合长度是8-9个氨基酸。我们设计了一个新的结合物，由CpG30和C-TRP2181-188肽（9-mer）组成，其中TRP2180-188的N-末端丝氨酸残基被半胱氨酸取代。通过调整肽的长度，我们成功地诱导了CpG30-C-TRP2181-188结合物免疫后产生强烈的TRP2180-188肽特异性CTL活性。此外，具有其他CpG-DNA序列或半胱氨酸类似物的各种CpG30-C-TRP2181-188结合物也诱导相同水平的CTL活性。因此，通过将N-末端的氨基酸残基替换为半胱氨酸残基制备的CpG-C肽结合物，可能成为针对癌症和传染病特定抗原的肽疫苗的新型有效平台。

Recent studies have shown the potent efficacy of peptide-based vaccines for cancer immunotherapy. Immunological performance is optimized through the co-delivery of adjuvant and antigenic peptide molecules to antigen-presenting cells simultaneously. In our previous study, we showed that a conjugate consisting of 40-mer CpG-DNA and an antigenic ovalbumin peptide through disulfide bonding could efficiently induce ovalbumin-specific cytotoxic T lymphocyte (CTL) responses in vivo. In this study, based on the conjugation design, we prepared a conjugate consisting of 30-mer CpG-DNA (CpG30) and a cancer antigenic peptide of Tyrosinase-related protein 2 (TRP2180-188) using a cysteine residue attached at the N-terminus of TRP2180-188. However, the immunization of mice with this conjugate did not induce efficient TRP2180-188-specific immune responses. It was thought that the resultant peptide (10-mer) cleaved from the conjugate might be too long to fit into the H-2Kb molecule because the optimal length for binding to it is 8-9 amino acids. We newly designed a conjugate consisting of CpG30 and the C-TRP2181-188 peptide (9-mer), in which the N-terminal serine residue of TRP2180-188 is replaced by a cysteine. By adjusting the peptide length, we succeeded in inducing strong TRP2180-188 peptide-specific CTL activity upon immunization with the CpG30-C-TRP2181-188 conjugate. Furthermore, various CpG30-C-TRP2181-188 conjugates having other CpG-DNA sequences or cysteine analogues also induced the same level of CTL activity. Therefore, CpG-C-peptide conjugates prepared by replacement of the amino acid residue at the N-terminus with a cysteine residue could be a new and effective platform for peptide vaccines for targeting specific antigens of cancers and infectious diseases.