Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China.
Int Immunopharmacol. 2013 Aug;16(4):505-10. doi: 10.1016/j.intimp.2013.04.027. Epub 2013 May 11.
Chlamydia abortus (C. abortus) is an obligate intracellular pathogen that causes abortion in pigs and poses a zoonotic risk in pregnant women. Although attenuated and inactivated vaccines are available, they do not provide complete protection in animals underlining the need to develop new vaccines. In this study, we tested the hypothesis that intramuscular immunization with an ompA-based phage-mediated DNA chlamydial vaccine candidate will induce significant antigen-specific cellular and humoral immune responses. Thus, groups of piglets (five per group) were immunized intramuscularly with the phage-MOMP vaccine (λ-MOMP) or a commercial live-attenuated vaccine (1B vaccine) or a GFP-expressing phage (λ-GFP) or phosphate buffered saline (PBS) (control) and antigen-specific cell-mediated and humoral immune responses were evaluated. By day 63 post-immunization, the λ-MOMP vaccine elicited significantly higher (P<0.05) levels of antigen-specific serum IgG antibody responses than the 1B vaccine or control did. Also, piglets immunized with λ-MOMP vaccine had significantly higher (P<0.05) MOMP-specific lymphocyte proliferative responses compared to those immunized with the 1B vaccine or control. Furthermore, the total T-cell numbers (CD3+) and the proportion of CD4+ and CD8+ T-cell subsets as well as the ratio of CD4+/CD8+ T cells elicited following immunization were comparable between the λ-MOMP- and 1B-vaccinated animals on both days 63 and 70. Interestingly, although the proportion of CD3+CD4-CD8- double negative T cells on day 63 was significantly higher (P<0.05) in the 1B vaccine group compared to the λ-MOMP-immunized group, there was a significant decrease in the proportion of this T-cell population on day 70 in the 1B compared to the λ-MOMP vaccinated group. These results indicate that the λ-MOMP DNA vaccine is capable of inducing antigen-specific cellular and humoral immune responses that may provide protective immunity against a live challenge infection with C. abortus.
沙眼衣原体（C. abortus）是一种专性细胞内病原体，可导致猪流产，并对孕妇构成人畜共患病风险。虽然有减毒和灭活疫苗可用，但它们并不能为动物提供完全保护，这突显了开发新疫苗的必要性。在这项研究中，我们检验了这样一个假设，即通过肌肉内免疫以 ompA 为基础的噬菌体介导的衣原体候选 DNA 疫苗将诱导显著的抗原特异性细胞和体液免疫应答。因此，将猪仔（每组五只）分组进行肌肉内免疫，使用噬菌体-MOMP 疫苗（λ-MOMP）或商业减毒活疫苗（1B 疫苗）或 GFP 表达噬菌体（λ-GFP）或磷酸盐缓冲盐水（PBS）（对照），并评估抗原特异性细胞介导和体液免疫应答。在免疫后第 63 天，λ-MOMP 疫苗引发的抗原特异性血清 IgG 抗体应答水平明显高于 1B 疫苗或对照（P<0.05）。此外，与免疫接种 1B 疫苗或对照相比，用 λ-MOMP 疫苗免疫的猪仔的 MOMP 特异性淋巴细胞增殖反应显著更高（P<0.05）。此外，在第 63 天和第 70 天，λ-MOMP 和 1B 疫苗接种动物的总 T 细胞数（CD3+）以及 CD4+和 CD8+T 细胞亚群的比例以及 CD4+/CD8+T 细胞的比值均无差异。有趣的是，尽管 1B 疫苗组的 CD3+CD4-CD8-双阴性 T 细胞比例在第 63 天明显高于 λ-MOMP 免疫组（P<0.05），但在第 70 天，1B 疫苗组中的该 T 细胞群比例明显低于 λ-MOMP 疫苗组。这些结果表明，λ-MOMP DNA 疫苗能够诱导抗原特异性细胞和体液免疫应答，可能为针对活的 C. abortus 感染提供保护性免疫。
