Cruz-Muñoz Mario E, Fuentes-Pananá Ezequiel M
Laboratorio de Inmunología Molecular, Facultad de Medicina, Universidad Autónoma del Estado de Morelos, Cuernavaca, Mexico.
Unidad de Investigación en Virología y Cáncer, Hospital Infantil de México Federico Gómez, Mexico City, Mexico.
Front Microbiol. 2018 Jan 5;8:2521. doi: 10.3389/fmicb.2017.02521. eCollection 2017.
Viruses are the most abundant and diverse biological entities in the planet. Historically, our main interest in viruses has focused on their pathogenic role, recognized by pandemics that have decimated the world population. However, viral infections have also played a major role in the evolution of cellular organisms, both through interchanging of genes with novel functions and shaping the immune system. Examples abound of infections that seriously compromise the host integrity, but evidence of plant and insect viruses mutualistic relationships have recently surfaced in which infected hosts are better suited for survival, arguing that virus-host interactions are initially parasitic but become mutualistic over years of co-evolution. A similar mutual help scenario has emerged with commensal gut bacteria. EBV is a herpesvirus that shares more than a hundred million years of co-evolution with humans, today successfully infecting close to 100% of the adult world population. Infection is usually acquired early in childhood persisting for the host lifetime mostly without apparent clinical symptoms. Disturbance of this homeostasis is rare and results in several diseases, of which the best understood are infectious mononucleosis and several EBV-associated cancers. Less understood are recently found inborn errors of the immune system that result in primary immunodeficiencies with an increased predisposition almost exclusive to EBV-associated diseases. Puzzling to these scenarios of broken homeostasis is the co-existence of immunosuppression, inflammation, autoimmunity and cancer. Homologous to EBV, HCMV, HHV-6 and HHV-7 are herpesviruses that also latently infect most individuals. Several lines of evidence support a mutualistic equilibrium between HCMV/EBV and hosts, that when altered trigger diseases in which the immune system plays a critical role. Interestingly, these beta and gamma herpesviruses persistently infect all immune lineages and early precursor cells. In this review, we will discuss the evidence of the benefits that infection of immune cells with these herpesviruses brings to the host. Also, the circumstances in which this positive relationship is broken, predisposing the host to diseases characterized by an abnormal function of the host immune system.
病毒是地球上数量最多、种类最多样的生物实体。从历史上看，我们对病毒的主要兴趣集中在它们的致病作用上，这在曾使世界人口锐减的大流行中得到了认可。然而，病毒感染在细胞生物体的进化中也发挥了重要作用，既通过与具有新功能的基因交换，也通过塑造免疫系统。严重损害宿主完整性的感染例子比比皆是，但植物和昆虫病毒互利共生关系的证据最近浮出水面，在这种关系中，受感染的宿主更适合生存，这表明病毒与宿主的相互作用最初是寄生性的，但经过多年的共同进化后会变成互利共生。一种类似的互助情况也出现在共生肠道细菌中。EB病毒是一种疱疹病毒，与人类有着超过一亿年的共同进化史，如今成功感染了近100%的成年世界人口。感染通常在儿童早期获得，并在宿主一生中持续存在，大多数情况下没有明显的临床症状。这种内环境稳态的紊乱很少见，会导致几种疾病，其中最广为人知的是传染性单核细胞增多症和几种与EB病毒相关的癌症。最近发现的导致原发性免疫缺陷的先天性免疫系统错误鲜为人知，这些缺陷几乎只增加了患EB病毒相关疾病的易感性。与这些内环境稳态破坏情况令人困惑的是免疫抑制、炎症、自身免疫和癌症的共存。与EB病毒同源的人巨细胞病毒、HHV - 6和HHV - 7也是疱疹病毒，它们也潜伏感染大多数个体。几条证据支持人巨细胞病毒/EB病毒与宿主之间的互利共生平衡，这种平衡一旦改变就会引发免疫系统起关键作用的疾病。有趣的是，这些β和γ疱疹病毒持续感染所有免疫谱系和早期前体细胞。在这篇综述中，我们将讨论这些疱疹病毒感染免疫细胞给宿主带来益处的证据。此外，还将讨论这种积极关系被打破的情况，这种情况会使宿主易患以宿主免疫系统功能异常为特征的疾病。
