Departamento de Biología, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, Mexico.
Instituto Nacional de Salud Pública, Cuernavaca, Morelos, Mexico.
Microb Pathog. 2018 Dec;125:93-95. doi: 10.1016/j.micpath.2018.09.012. Epub 2018 Sep 7.
Immune priming in invertebrates occurs when the first contact with a pathogen/parasite enhances resistance after a second encounter with the same strain or species. Although the mechanisms are not well understood, there is evidence that priming the immune response of some hosts leads to greater pro-oxidant production. Parasites, in turn, might counteract the host attack with antioxidants. Virulent pathogen strains may therefore mask invertebrate immune priming. For example, different parasite species overexpress catalase as a virulence factor to resist host pro-oxidants, possibly impairing the immune priming response. The aim of this study was firstly to evaluate the specificity of immune priming in Tenebrio molitor when facing homologous and heterologous challenges. Secondly, homologous challenges were carried out with two Metarhizium anisopliae strains (Ma10 and CAT). The more virulent strain (CAT) overexpresses catalase, an antioxidant that perhaps impairs a host immune response mediated by reactive oxygen species (ROS). Indeed, T. molitor larvae exhibited better immune priming (survival) in response to the Ma10 than CAT homologous challenge. Moreover, the administration of paraquat, an ROS-promoting agent, favoured survival of the host upon exposure to each fungal strain. We propose that some pathogens likely overcome pro-oxidant-mediated immune priming defences by producing antioxidants such as catalase.
无脊椎动物的免疫启动是指第一次接触病原体/寄生虫后，第二次接触同一菌株或物种时增强了抵抗力。尽管其机制尚不清楚，但有证据表明，一些宿主的免疫反应被激活后会产生更多的促氧化剂。作为回应，寄生虫可能会用抗氧化剂来对抗宿主的攻击。因此，有毒病原体菌株可能会掩盖无脊椎动物的免疫启动。例如，不同的寄生虫物种过度表达过氧化氢酶作为一种毒力因子来抵抗宿主的促氧化剂，这可能会损害免疫启动反应。本研究的目的首先是评估在面对同源和异源挑战时，黄粉虫的免疫启动的特异性。其次，用两种绿僵菌菌株（Ma10 和 CAT）进行同源性挑战。毒力更强的菌株（CAT）过度表达了一种抗氧化剂过氧化氢酶，它可能会损害由活性氧物质（ROS）介导的宿主免疫反应。事实上，与 CAT 同源性挑战相比，黄粉虫幼虫对 Ma10 的免疫启动（存活率）更好。此外，施用促进 ROS 产生的百草枯，有利于宿主在接触每种真菌菌株时的存活。我们提出，一些病原体可能通过产生抗氧化剂（如过氧化氢酶）来克服由促氧化剂介导的免疫启动防御。
