Surprising Benefits of Virovores: An Organism That Eats Viruses

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Surprising Benefits of Virovores: An Organism That Eats Viruses

Many viruses are known to cause diseases and have therefore been the focus of virology research. However, viruses also play important roles in ecosystem processes, such as lysing microbes and releasing nutrients, as well as indirectly causing host mortality. While viruses have typically been studied as predators in these contexts, they can also serve as food for other organisms. Foragers that consume water, soil particles, or leaves often ingest virus particles, and some ciliates and flagellates may consume significant numbers of viruses. This process, known as virovory, has not been well studied in terms of its potential to influence population growth and alter energy flow in food webs.

To investigate this potential, the authors measured the population growth of Halteria sp. and Paramecium bursaria in foraging trials with and without supplemental chloroviruses. They also used fluorescent microscopy to confirm the ingestion of chloroviruses by ciliates and tracked the reduction in chloroviruses, fitting a classic trophic link model to the data to determine whether the Halteria-chlorovirus interaction could be viewed as a trophic interaction.

The authors found that both Halteria and Paramecium reduced chlorovirus plaque-forming units (PFUs) by up to two orders of magnitude in 2 days, and that fluorescent images showed chloroviruses in vacuoles within the ciliates. This demonstrates a large flow of energy and matter from virus populations to consumers. In foraging trials, Halteria demonstrated robust growth with only chloroviruses as food, while controls with chloroviruses filtered out showed minimal to no growth. This suggests that some ciliates can consume enough virus particles to foster population growth, at a level similar to protist growth generally. In contrast, the abundance of Paramecium did not increase in either treatment or control trials, indicating that not all ciliates can grow on chloroviruses in these conditions, even when they consume them. Dynamics of Halteria and chlorovirus abundances fit well to a trophic interaction model, with estimates of key interaction parameters including space clearance rate and conversion efficiency.

These results suggest that virovory may play a role in shaping population dynamics and ecosystem functioning. Small protists that consume viruses are themselves consumed by zooplankton, so this viral-derived energy and matter may move up through aquatic food webs, altering their structure and dynamics. Protists represent a large fraction of living biomass and their grazing plays a major role in aquatic food webs, but current models of aquatic food webs and ecosystems do not include the trophic link between viruses and their consumers. This research indicates that current food web models are missing a critical interaction and suggests that this link should be included in future models. Further research is needed to understand the full extent and importance of virovory in aquatic ecosystems.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_column_text]Sources: [1][2][/vc_column_text][/vc_column][/vc_row]


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