Parents invest in their offspring by preparing them for defense against pathogens and parasites that only the parents have encountered, a phenomenon known as transgenerational immune priming (TGIP). The priming effect can be passed maternally or paternally to the next generation, thus increasing the survival of offspring exposed to the same pathogen. The scope of the resulting immune response can be narrow (primarily targeting the triggering pathogen) or much more general, depending on the underlying mechanism. Maternal TGIP is often narrowly focused because the major mechanism is the transfer of microbes or fragments thereof, encountered by mothers at the larval stage, to the developing eggs along with the uptake of lipophorins and vitellogenins. This induces the expression of zygotic defense genes, including those encoding antimicrobial peptides (AMPs), comparable to the defenses observed in the larvae and adults. Maternal TGIP does not appear to involve the direct vertical transmission of immunity-related effectors such as AMPs (or the corresponding mRNAs) to the eggs. Parental investment in offspring is also mediated by epigenetic mechanisms such as DNA methylation, histone acetylation and microRNA expression, which can be imprinted on the gametes by either parent without changes in the DNA sequence. Epigenetic inheritance is the only known mechanism of paternal TGIP, and results in a more general fortification of the immune response. This review considers the mechanistic basis of TGIP, its role in evolutionary processes such as the establishment of resistance against pathogens, and the impact of pathogens and parasites on the epigenetic machinery of host insects.

父母投资于他们的后代，让他们准备好防御只有父母遇到的病原体和寄生虫，这种现象被称为跨代免疫启动 (TGIP)。启动效应可以母系或父系传递给下一代，从而增加暴露于相同病原体的后代的存活率。由此产生的免疫反应的范围可能很窄（主要针对触发病原体）或更普遍，这取决于潜在的机制。母体 TGIP 通常被狭隘地关注，因为主要机制是将母体在幼虫阶段遇到的微生物或其片段与脂蛋白和卵黄蛋白的摄取一起转移到发育中的卵子。这会诱导合子防御基因的表达，包括那些编码抗菌肽（AMP）的，与在幼虫和成虫中观察到的防御相当。母体 TGIP 似乎不涉及免疫相关效应物（如 AMP（或相应的 mRNA））直接垂直传递到卵子。亲本对后代的投资也受表观遗传机制介导，例如 DNA 甲基化、组蛋白乙酰化和 microRNA 表达，这些机制可以由任一亲本印在配子上，而不会改变 DNA 序列。表观遗传是父系 TGIP 的唯一已知机制，并导致更普遍的免疫反应强化。这篇综述考虑了 TGIP 的机制基础，它在进化过程中的作用，例如建立对病原体的抵抗力，