# Therapeutic Use of Parerythrobacter sp. M20A3S10, a Marine Bacterium, Targeting Influenza Viruses and Flaviviruses

## TL;DR

A marine bacterium extract shows antiviral effects against influenza and flaviviruses, suggesting potential for new treatments.

## Contribution

Discovery of a marine bacterial extract with broad-spectrum antiviral activity against multiple RNA viruses.

## Key findings

- The extract from Parerythrobacter sp. M20A3S10 reduced replication of influenza and flaviviruses in infected cells.
- Post-infection treatment with the extract was effective, indicating a possible host-modulating mechanism.
- Marine bacteria may serve as a new source of antiviral compounds for veterinary and public health.

## Abstract

Viruses that affect both animals and humans, such as influenza, Zika, and dengue, are spreading more easily across the world due to global travel, climate change, and close contact between people, animals, and insects. These viruses are difficult to control because they can change quickly and escape the body’s natural defenses. In this study, we looked for new ways to fight these viruses using substances made by bacteria found in the ocean. We tested a natural extract from one marine bacterium and found that it could reduce the ability of several viruses to grow in infected cells. This included viruses that commonly affect animals and that can also spread to people. The extract worked after the cells were already infected, showing promise as a possible treatment option. Although we do not yet know the exact ingredient in the extract responsible for this effect, our results suggest that marine bacteria could be a valuable new source of antiviral compounds. This discovery is significant as it may facilitate the development of improved therapeutics for animals and help reduce the risk of zoonotic viral transmission.

Emerging RNA viruses such as influenza A virus (IAV), Zika virus (ZIKV), and dengue virus (DENV) continue to pose major challenges to animal and public health due to their high mutation rates, wide host ranges, and immune evasion strategies. In this study, we evaluated the in vitro antiviral activity of a marine bacterial extract derived from Parerythrobacter sp. M20A3S10 against IAV (H1N1; H3N2), influenza B virus (IBV), ZIKV, and DENV2. The extract demonstrated broad-spectrum antiviral effects with favorable selectivity indices across multiple host-derived epithelial cell lines. Notably, post-infection treatment significantly suppressed viral replication, suggesting a host-modulating or replication-inhibiting mechanism. While the extract’s active components have yet to be identified, bacteria from the Erythrobacteraceae family are known producers of bioactive metabolites with potential antiviral properties. These findings provide preliminary insight into the potential of marine-derived bacterial compounds in veterinary antiviral development and highlight the need for further characterization and in vivo validation. This work contributes to the understanding of virus–host interactions and the exploration of novel therapeutic strategies targeting the pathogenesis and immune modulation of veterinary RNA viruses.