Virovory: control of viral pathogenesis by the protists and the way forward

The interactions between viruses and protists have been crucially impacting the ecosystem. In recent studies, it has been found that the protists are not only able to consume, ingest or inactivate a variety of viruses, resulting in a reduction of the viral load, but instead, they can treat viruses as the exclusive source of nutrients, exhibiting "Virovory" (virus-only diet). These small protists can act as virosomes (organisms harnessing nutrients from the viruses) and utilize the viruses as the only source of nourishment, implying the protist to multiply and grow. The viral reduction was previously thought to be only because of the action of abiotic factors (temperature, ultraviolet light, chemicals, membrane adsorption, etc.). However, virovory suggests that organic material flow in microbial communities, the impact of viruses on the food web and, the role of protists in regulating viral populations are crucial factors in ecosystem dynamics. In this review, ingestion, digestion, and inactivation of a variety of viruses by protists are discussed. Several questions can be answered by further research on understanding the mechanisms behind the inactivation of viruses, the impact of reduced viral load on other microbial populations, and the large-scale employability of these little protists in removing pathogenic viruses from the environment.