Am Nat. 2019 Feb;193(2):296-308. doi: 10.1086/701122. Epub 2018 Dec 20.
Social immunity moderates the spread of pathogens in social groups and is especially likely in groups structured by genetic relatedness. The extent to which specific immune pathways are used is unknown. Here, we investigate the expression and social role of three functionally separate immune genes (pgrp-sc2, thaumatin, and defensin) during parental care in the beetle Nicrophorus vespilloides. These genes reside in different immune pathways, allowing us to test whether specific components of the immune system are targeted for social immunity. To test for the evolution of specificity, we manipulated the influence of social context and timing on gene expression and quantified the covariance of maternal immune gene expression and offspring fitness. Larvae reduced expression of all three genes in the presence of parents. Parental pgrp-sc2 and thaumatin increased during direct parenting, while defensin was upregulated before larvae arrived. Parental expression of pgrp-sc2 and thaumatin responded similarly to experimental manipulation of timing and presence of larvae, which differed from the response of defensin. We found a positive covariance between maternal expression and offspring fitness for pgrp-sc2 and thaumatin but not defensin. We suggest that social immunity can involve specific genes and pathways, reflecting evolution as an interacting phenotype during parenting.
社会免疫调节了病原体在社会群体中的传播，特别是在由遗传相关性构成的群体中。具体使用哪些特定的免疫途径尚不清楚。在这里，我们研究了在甲虫 Nicrophorus vespilloides 的亲代养育过程中，三个功能独立的免疫基因（pgrp-sc2、thaumatin 和 defensin）的表达和社会角色。这些基因位于不同的免疫途径中，使我们能够测试免疫系统的特定成分是否针对社会免疫进行了靶向。为了测试特异性的进化，我们操纵了社会环境和时间对基因表达的影响，并量化了母系免疫基因表达与后代适应性之间的协方差。幼虫在有父母存在的情况下会减少这三种基因的表达。亲代的 pgrp-sc2 和 thaumatin 在直接育儿时增加，而 defensin 在幼虫到达之前上调。pgrp-sc2 和 thaumatin 的亲代表达对幼虫存在和时间的实验操纵的反应相似，与 defensin 的反应不同。我们发现 pgrp-sc2 和 thaumatin 的母系表达与后代适应性之间存在正协方差，但 defensin 则没有。我们认为，社会免疫可以涉及特定的基因和途径，反映了在亲代养育过程中作为相互作用表型的进化。
