South Texas Center for Emerging Infectious Diseases and Center for Excellence in Infection Genomics, Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, United States; Department of Pathology and Department of Dental Medicine, Midwestern University, Downers Grove, IL 60515, United States.
Vaccine. 2013 Nov 19;31(48):5722-8. doi: 10.1016/j.vaccine.2013.09.036. Epub 2013 Oct 1.
Vaccination with recombinant chlamydial protease-like activity factor (rCPAF) has been shown to provide robust protection against genital Chlamydia infection. Adoptive transfer of IFN-γ competent CPAF-specific CD4⁺ T cells was sufficient to induce early resolution of chlamydial infection and reduction of subsequent pathology in recipient IFN-γ-deficient mice indicating the importance of IFN-γ secreting CD4⁺ T cells in host defense against Chlamydia. In this study, we identify CD4⁺ T cell reactive CPAF epitopes and characterize the activation of epitope-specific CD4⁺ T cells following antigen immunization or Chlamydia challenge. Using the HLA-DR4 (HLA-DRB1*0401) transgenic mouse for screening overlapping peptides that induced T cell IFN-γ production, we identified at least 5 CPAF T cell epitopes presented by the HLA-DR4 complex. Immunization of HLA-DR4 transgenic mice with a rCPAFep fusion protein containing these 5 epitopes induced a robust cell-mediated immune response and significantly accelerated the resolution of genital and pulmonary Chlamydia infection. rCPAFep vaccination induced CPAF-specific CD4⁺ T cells in the spleen were detected using HLA-DR4/CPAF-epitope tetramers. Additionally, CPAF-specific CD4⁺ clones could be detected in the mouse spleen following Chlamydia muridarum and a human Chlamydia trachomatis strain challenge using these novel tetramers. These results provide the first direct evidence that a novel CPAF epitope vaccine can provide protection and that HLA-DR4/CPAF-epitope tetramers can detect CPAF epitope-specific CD4⁺ T cells in HLA-DR4 mice following C. muridarum or C. trachomatis infection. Such tetramers could be a useful tool for monitoring CD4⁺ T cells in immunity to Chlamydia infection and in developing epitope-based human vaccines using the murine model.
用重组衣原体蛋白酶样活性因子（rCPAF）进行免疫接种已被证明能为预防生殖器衣原体感染提供强大的保护。过继转移 IFN-γ 功能正常的 CPAAF 特异性 CD4+T 细胞足以诱导衣原体感染的早期消退，并减少接受 IFN-γ 缺陷型小鼠的后续病理学改变，这表明 IFN-γ 分泌的 CD4+T 细胞在宿主抵抗衣原体感染中很重要。在这项研究中，我们确定了 CD4+T 细胞反应性 CPAAF 表位，并描述了抗原免疫接种或衣原体挑战后表位特异性 CD4+T 细胞的激活。使用 HLA-DR4（HLA-DRB1*0401）转基因小鼠筛选诱导 T 细胞 IFN-γ 产生的重叠肽，我们鉴定了至少 5 个由 HLA-DR4 复合物呈递的 CPAAF T 细胞表位。用含有这 5 个表位的 rCPAFep 融合蛋白免疫 HLA-DR4 转基因小鼠，可诱导强烈的细胞免疫反应，并显著加速生殖道和肺部衣原体感染的消退。用 HLA-DR4/CPAF-表位四聚体检测到用 rCPAFep 疫苗免疫的 HLA-DR4 转基因小鼠脾内的 CPAAF 特异性 CD4+T 细胞。此外，在使用这些新型四聚体对鼠型沙眼衣原体和人型沙眼衣原体株进行挑战后，可在小鼠脾内检测到 CPAAF 特异性 CD4+克隆。这些结果首次直接证明，新型 CPAAF 表位疫苗可提供保护，并且 HLA-DR4/CPAF-表位四聚体可在 C. muridarum 或 C. trachomatis 感染后检测到 HLA-DR4 小鼠中的 CPAAF 表位特异性 CD4+T 细胞。此类四聚体可能是监测衣原体感染免疫中 CD4+T 细胞的有用工具，并可在使用鼠模型开发基于表位的人类疫苗方面发挥作用。
