Data from: Immune priming specificity within and across generations reveals the range of pathogens affecting evolution of immunity in an insect

1. Many organisms can improve their immune response as a function of their immunological experience or that of their parents. This phenomenon, called immune priming, has likely evolved from repetitive challenges by the same pathogens during the host lifetime or across generation. 2. All pathogens may not expose host to the same probability of re-infection and immune priming is expected to evolve from pathogens exposing the host to the greatest probability of re-infection. Under this hypothesis, the priming response to these pathogens should be specifically more efficient and less costly than to others. 3. We examined the specificity of immune priming within and across generations in the mealworm beetle, Tenebrio molitor, by comparing survival of individuals to infection with bacteria according to their own immunological experience or that of their mother with these bacteria. 4. We found that insects primed with Gram-positive bacteria became highly protected against both Gram-positive and Gram-negative bacterial infections, mainly due to an induced persistent antibacterial response, which did not exist in insects primed with Gram-negative bacteria. Insects primed with Gram-positive bacteria also exhibited enhanced concentration of hemocytes, but their implication in acquired resistance was not conclusive because of the persistent antibacterial activity in the hemolymph. Offspring maternally primed with Gram-positive and Gram-negative bacteria exhibited similarly improved immunity, whatever the bacteria used for the infection. Such maternal protection was costly in the larval development of offspring, but this cost was lower for offspring maternally primed with Gram-positive bacteria. 5. While T. molitor can develop some levels of primed response to Gram-negative bacteria, the priming response to Gram-positive bacteria was more efficient and less costly. We concluded that Gram-positive bacterial pathogens were of great importance in the evolution of immune priming in this insect species.1. 许多生物体可依据自身或亲本的免疫经历增强免疫应答。这一被称为免疫致敏（immune priming）的现象，很可能是在宿主生命周期内或跨世代遭遇同一病原体反复侵染的过程中演化而来的。 2. 并非所有病原体使宿主面临再次感染的概率都相同，免疫致敏理论预期，该现象会在那些使宿主拥有最高再次感染概率的病原体驱动下演化。根据这一假说，相较于其他病原体，针对这类病原体的致敏应答应具备更高效、更低成本的特征。 3. 本研究以黄粉虫（Tenebrio molitor）为研究对象，通过对比个体及其母亲对特定细菌的免疫经历与感染后存活率的关系，探究了其体内及跨世代的免疫致敏特异性。 4. 研究结果显示，经革兰氏阳性菌（Gram-positive bacteria）致敏的甲虫，对革兰氏阳性菌与革兰氏阴性菌（Gram-negative bacteria）感染均展现出显著的保护效果，这主要源于诱导产生的持续性抗菌应答——而经革兰氏阴性菌致敏的甲虫并未出现此类应答。经革兰氏阳性菌致敏的甲虫，其血细胞（hemocytes）浓度也有所升高，但由于血淋巴（hemolymph）中存在持续性抗菌活性，血细胞在获得性抗性中的具体作用仍未得到明确证实。经革兰氏阳性菌或革兰氏阴性菌致敏的母体所产生的后代，其免疫水平均得到了相似程度的提升，且与后代感染所用的细菌种类无关。这类母体介导的致敏保护会对后代幼虫的发育产生适应性代价，但经革兰氏阳性菌致敏的母体所产后代承担的此类代价更低。 5. 尽管黄粉虫对革兰氏阴性菌可产生一定程度的致敏应答，但针对革兰氏阳性菌的致敏应答效率更高、成本更低。本研究最终得出结论：革兰氏阳性菌病原体在该昆虫物种的免疫致敏演化过程中发挥了关键作用。