The collection of organisms inhabiting the human body, the microbiome, is an integral component of our physiology. In particular, the bacterial members of the microbiome are proposed to mediate phenotypic differences between individuals, much like gene variants in the host genome. These symbiotic bacteria are in a position to have an influential impact on our biology because they are numerous, diverse, differ between individuals, and interact with the host and each other over a long period of time. These qualities also describe the collection of viruses that inhabit our body, and thus the virome is in a similar position as the bacterial microbiome to impact human health and disease.

By any criterion, the size and diversity of the virome is staggering. The mammalian virome includes viruses that infect cells of the animal host, endogenous viral elements, and viruses that infect members of the microbiome, most notably phages that replicate in bacteria. All adult humans are chronically infected with multiple RNA and DNA animal viruses, ranging from traditional pathogens to those that are most often innocuous but harmful in a small fraction of the population. Viruses that fall into the categories of commensal and opportunistic pathogen include many that are detected in the majority of the adult human population, such as members of the herpesvirus, polyomavirus, adenovirus, circovirus, and anellovirus families.

Chronic infections are likely to delay or prolong immunomodulation. Many viruses establish latency, a state in which the viral genome persists within a cell without producing infectious viral particles. During latency, the virus is less visible due to decreased metabolic activity and amount of antigens available for detection by receptors of the innate and adaptive immune system. Viruses that display continuous replication employ other strategies to persist. HBV evokes an unusually low innate immune response by inhibiting multiple steps of the type I interferon (IFN-I) induction and signaling pathway, which likely allows this virus to reside in the liver over the lifetime of the infected individual. Lymphocytic choriomenengitis virus (LCMV) and murine norovirus (MNV) strains that establish persistent infections in mice evoke suboptimal T cell responses compared with acute strains that are successfully eradicated.

Media Contact:

Sophie Kate
Managing Editor
Microbiology: Current Research
Email: aamcr@alliedacademies.org