Richard JC et al. (2020), Mass mortality in freshwater mussels (Actinonai...

ECB-ART-49638

Sci Rep 2020 Sep 02;101:14498. doi: 10.1038/s41598-020-71459-z.

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Mass mortality in freshwater mussels (Actinonaias pectorosa) in the Clinch River, USA, linked to a novel densovirus.

Richard JC , Leis E , Dunn CD , Agbalog R , Waller D , Knowles S , Putnam J , Goldberg TL .

Abstract
Freshwater mussels (order Unionida) are among the world's most biodiverse but imperiled taxa. Recent unionid mass mortality events around the world threaten ecosystem services such as water filtration, nutrient cycling, habitat stabilization, and food web enhancement, but causes have remained elusive. To examine potential infectious causes of these declines, we studied mussels in Clinch River, Virginia and Tennessee, USA, where the endemic and once-predominant pheasantshell (Actinonaias pectorosa) has suffered precipitous declines since approximately 2016. Using metagenomics, we identified 17 novel viruses in Clinch River pheasantshells. However, only one virus, a novel densovirus (Parvoviridae; Densovirinae), was epidemiologically linked to morbidity. Clinch densovirus 1 was 11.2 times more likely to be found in cases (moribund mussels) than controls (apparently healthy mussels from the same or matched sites), and cases had 2.7 (log10) times higher viral loads than controls. Densoviruses cause lethal epidemic disease in invertebrates, including shrimp, cockroaches, crickets, moths, crayfish, and sea stars. Viral infection warrants consideration as a factor in unionid mass mortality events either as a direct cause, an indirect consequence of physiological compromise, or a factor interacting with other biological and ecological stressors to precipitate mortality.

PubMed ID: 32879395
PMC ID: PMC7468154
Article link: Sci Rep

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Abascal, TranslatorX: multiple alignment of nucleotide sequences guided by amino acid translations. 2010, Pubmed

	Figure 1. Map of sampling locations. The map was created using ArcMap version 10.4.1 (Esri, Redlands, California, USA; https://support.esri.com/en/products/desktop/arcgis-desktop/arcmap/10-4-1).
	Figure 2. Frequency distribution of viral richness (number of viruses) and viral load (log10 viral reads per 106 total reads per kilobase of target sequence) in Clinch River pheasantshell cases and controls.
	Figure 3. Heatmap of viral loads in Clinch River pheasantshells. Data are log10 viral reads per 106 total reads per kilobase of target sequence for each virus separately (viruses A–Q) and for all viruses combined (All). Data are presented separately for cases and controls in 2017 and 2018. Raw data on viral loads are presented in Table S2.