Successful vaccines against specific pathogens often require multiple immunizations and adjuvant usage. Yet, assessing the protective efficacy of different immunization regimens with adjuvanted Toxoplasma gondii vaccines remains elusive. In this study, we investigated the vaccine efficacy induced by CpG-ODN-adjuvanted T. gondii virus-like particles (VLPs) after challenge infection with T. gondii (ME49) in mice (BALB/c) upon one, two, and three immunizations. Immunization with adjuvanted T. gondii VLPs induced higher levels of T. gondii-specific IgG and/or IgA antibody responses, germinal center (GC) B cells, total B cells, and CD4⁺ and CD8⁺ T cells compared with unadjuvanted VLPs. Increasing the number of immunizations was strongly correlated with enhanced protective immunity against T. gondii in mice, with the highest protection being demonstrated in mice thrice-immunized with either adjuvanted T. gondii VLPs or VLPs alone. Notably, lesser bodyweight reductions and cerebral cyst counts were observed in mice receiving multiple immunizations with the adjuvanted VLPs, thereby confirming the effectiveness of adjuvanted boost immunizations. These results demonstrated that multiple immunizations with T. gondii VLPs is an effective approach, and the CpG-ODN can be developed as an effective adjuvant for T. gondii VLP vaccines.

中文翻译：

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一次，二次和三次免疫后评估CpG-ODN佐剂弓形虫病毒颗粒疫苗

成功的针对特定病原体的疫苗通常需要多次免疫和佐剂使用。但是，用佐剂弓形虫疫苗评估不同免疫方案的保护效果仍然很困难。在这项研究中，我们调查了由CpG-ODN佐剂的弓形虫病毒样颗粒（VLPs）在小鼠（BALB / c）感染一，二和三天后，感染了弓形虫（ME49）后诱导的疫苗功效。免疫。用佐剂的弓形虫VLP免疫可诱导更高水平的弓形虫特异性IgG和/或IgA抗体反应，生发中心（GC）B细胞，总B细胞以及CD4 ⁺和CD8 ⁺T细胞与未佐剂的VLP相比。免疫次数的增加与小鼠对弓形虫的保护性免疫力增强密切相关，在单独用佐剂性弓形虫VLP或VLP三次免疫的小鼠中显示出最高的保护作用。值得注意的是，在接受佐剂性VLP多次免疫的小鼠中，体重减轻和脑囊肿计数降低的幅度较小，从而证实了佐剂加强免疫的有效性。这些结果表明，用弓形虫VLP多次免疫是一种有效的方法，CpG-ODN可被开发为弓形虫VLP疫苗的有效佐剂。