Williams Trevor, Virto Cristina, Murillo Rosa, Caballero Primitivo
Instituto de Ecología ACXalapa, Mexico.
Bioinsecticidas Microbianos, Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas, Universidad Pública de NavarraMutilva, Spain.
Front Microbiol. 2017 Jul 17;8:1337. doi: 10.3389/fmicb.2017.01337. eCollection 2017.
Baculoviruses () are occluded DNA viruses that are lethal pathogens of the larval stages of some lepidopterans, mosquitoes, and sawflies (phytophagous Hymenoptera). These viruses have been developed as biological insecticides for control of insect pests and as expression vectors in biotechnological applications. Natural and laboratory populations frequently harbor covert infections by baculoviruses, often at a prevalence exceeding 50%. Covert infection can comprise either non-productive latency or sublethal infection involving low level production of virus progeny. Latency in cell culture systems involves the expression of a small subset of viral genes. In contrast, covert infection in lepidopterans is associated with differential infection of cell types, modulation of virus gene expression and avoidance of immune system clearance. The molecular basis for covert infection may reside in the regulation of host-virus interactions through the action of microRNAs (miRNA). Initial findings suggest that insect nudiviruses and vertebrate herpesviruses may provide useful analogous models for exploring the mechanisms of covert infection by baculoviruses. These pathogens adopt mixed-mode transmission strategies that depend on the relative fitness gains that accrue through vertical and horizontal transmission. This facilitates virus persistence when opportunities for horizontal transmission are limited and ensures virus dispersal in migratory host species. However, when host survival is threatened by environmental or physiological stressors, latent or persistent infections can be activated to produce lethal disease, followed by horizontal transmission. Covert infection has also been implicated in population level effects on host-pathogen dynamics due to the reduced reproductive capacity of infected females. We conclude that covert infections provide many opportunities to examine the complexity of insect-virus pathosystems at the organismal level and to explore the evolutionary and ecological relationships of these pathogens with major crop and forest pests.
杆状病毒是一种被包埋的DNA病毒，是某些鳞翅目昆虫、蚊子和叶蜂（植食性膜翅目昆虫）幼虫阶段的致命病原体。这些病毒已被开发用作控制害虫的生物杀虫剂，并作为生物技术应用中的表达载体。自然种群和实验室种群经常隐匿感染杆状病毒，感染率通常超过50%。隐匿感染可能包括非生产性潜伏或涉及低水平病毒后代产生的亚致死感染。细胞培养系统中的潜伏涉及一小部分病毒基因的表达。相比之下，鳞翅目昆虫中的隐匿感染与细胞类型的差异感染、病毒基因表达的调节以及免疫系统清除的避免有关。隐匿感染的分子基础可能在于通过微小RNA（miRNA）的作用对宿主-病毒相互作用的调节。初步研究结果表明，昆虫浓核病毒和脊椎动物疱疹病毒可能为探索杆状病毒隐匿感染的机制提供有用的类似模型。这些病原体采用混合模式传播策略，这取决于通过垂直和水平传播获得的相对适应性收益。当水平传播的机会有限时，这有助于病毒的持续存在，并确保病毒在迁徙宿主物种中的传播。然而，当宿主生存受到环境或生理压力源的威胁时，潜伏或持续感染可能会被激活，从而引发致命疾病，随后进行水平传播。隐匿感染还被认为会对宿主-病原体动态产生种群水平的影响，因为受感染雌性的繁殖能力会降低。我们得出结论，隐匿感染为在生物体水平上研究昆虫-病毒病理系统的复杂性以及探索这些病原体与主要农作物和森林害虫之间的进化和生态关系提供了许多机会。
