Epidemiological data and animal studies suggest that helminth infection exerts potent immunomodulatory effects that dampen host immunity against unrelated pathogens. Despite this notion, we unexpectedly discovered that prior helminth infection resulted in enhanced protection against subsequent systemic and enteric bacterial infection. A population of virtual memory CD8 T (CD8 T_VM) cells underwent marked expansion upon infection with the helminth Heligmosomoides polygurus by an IL-4-regulated, antigen-independent mechanism. CD8 T_VM cells disseminated to secondary lymphoid organs and established a major population of the systemic CD8 T cell pool. IL-4 production elicited by protein immunization or selective activation of natural killer T cells also results in the expansion of CD8 T_VM cells. Notably, CD8 T_VM cells expanded by helminth infection are sufficient to transfer innate non-cognate protection against bacteria to naïve animals. This innate non-cognate "collateral protection" mediated by CD8 T_VM might provide parasitized animals an advantage against subsequent unrelated infections, and represents a potential novel strategy for vaccination.

中文翻译：

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由蠕虫感染扩增的虚拟记忆 CD8 T 细胞可提供针对细菌感染的广泛保护。

流行病学数据和动物研究表明，蠕虫感染具有强大的免疫调节作用，可抑制宿主对不相关病原体的免疫力。尽管有这样的想法，我们还是出乎意料地发现，先前的蠕虫感染导致对随后的全身和肠道细菌感染的保护增强。虚拟记忆 CD8 T (CD8 T _VM ) 细胞群在感染寄生虫 Heligmosomoides polygurus 后通过 IL-4 调节的抗原非依赖性机制发生显着扩张。CD8 T _VM细胞传播到次级淋巴器官并建立了系统性 CD8 T 细胞库的主要群体。由蛋白质免疫或自然杀伤 T 细胞的选择性激活引起的 IL-4 产生也会导致 CD8 T 细胞的扩增_VM细胞。值得注意的是，通过蠕虫感染扩增的 CD8 T _VM细胞足以将针对细菌的先天非同源保护转移给幼稚动物。_{这种由 CD8 T VM}介导的先天性非同源“附带保护”可能为被寄生动物提供抵抗后续无关感染的优势，并代表一种潜在的疫苗接种新策略。