Chlamydia psittaci is the pathogen of psittacosis, and it has emerged as a significant public health threat. Because most infections are easily overlooked, a vaccine is recognized as the best solution to control the spread of C. psittaci. Our previous study showed that Pgp3 protein is efficacious as a subunit vaccine while not the best candidate due to the negative effects. Thus, in this study, we tested the ability of a tandem epitope vaccine candidate designated SP based on Pgp3-dominant epitopes to induce protective immunity against pulmonary chlamydial infection. BALB/c mice were intraperitoneally inoculated with multiepitope peptide antigens followed by intranasal infection with C. psittaci. We found that the multiepitope peptide antigens induced strong humoral and cellular immune responses with high Th1-related (IFN-γ and IL-2) and proinflammatory (IL-6) cytokine levels. Meanwhile, the pathogen burden and inflammatory infiltration were significantly reduced in lungs of SP-immunized mice after chlamydial challenge. In addition, the IFN-γ and IL-6 secretion levels in the infected lungs were substantially reduced. Overall, our findings demonstrate that the peptide vaccine SP plays a significant role with good immunogenicity and protective efficacy against C. psittaci lung infection in BALB/c mice, providing important insights towards understanding the potential of peptide vaccines as new vaccine antigens for inducing protective immunity against chlamydial infection.

中文翻译：

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对小鼠肺衣原体攻击的串联衣原体鹦鹉热Pgp3多表位肽疫苗的评估。

鹦鹉热衣原体是鹦鹉热的病原体，已成为重大的公共卫生威胁。由于大多数感染很容易被忽视，因此疫苗被认为是控制鹦鹉热衣原体传播的最佳解决方案。我们以前的研究表明，Pgp3蛋白可作为亚单位疫苗有效，但由于其负面作用，不是最佳候选者。因此，在这项研究中，我们测试了基于Pgp3优势表位的命名为SP的串联表位疫苗候选物诱导针对肺衣原体感染的保护性免疫的能力。BALB / c小鼠腹膜内接种多表位肽抗原，然后鼻内感染鹦鹉热衣原体。我们发现多表位肽抗原诱导了强烈的体液和细胞免疫反应，并具有高Th1相关性（IFN-γ和IL-2）和促炎性（IL-6）细胞因子水平。同时，衣原体攻击后，SP免疫小鼠肺部的病原体负担和炎性浸润明显减少。另外，感染肺中的IFN-γ和IL-6分泌水平大大降低。总体而言，我们的发现表明，肽疫苗SP在BALB / c小鼠中具有良好的免疫原性和对鹦鹉热衣原体肺部感染的保护作用，发挥了重要作用，为理解肽疫苗作为诱导保护性免疫的新疫苗抗原的潜力提供了重要见解。对抗衣原体感染。衣原体攻击后，SP免疫小鼠的肺部病原体负担和炎性浸润明显减少。另外，感染肺中的IFN-γ和IL-6分泌水平大大降低。总体而言，我们的发现表明，肽疫苗SP在BALB / c小鼠中具有良好的免疫原性和对鹦鹉热衣原体肺部感染的保护作用，发挥了重要作用，为理解肽疫苗作为诱导保护性免疫的新疫苗抗原的潜力提供了重要见解。对抗衣原体感染。衣原体攻击后，SP免疫小鼠的肺部病原体负担和炎性浸润明显减少。另外，感染肺中的IFN-γ和IL-6分泌水平大大降低。总体而言，我们的发现表明，肽疫苗SP在BALB / c小鼠中具有良好的免疫原性和对鹦鹉热衣原体肺部感染的保护作用，发挥了重要作用，为理解肽疫苗作为诱导保护性免疫的新疫苗抗原的潜力提供了重要见解。对抗衣原体感染。