Virome Variation during Sea Star Wasting Disease Progression in Pisaster ochraceus (Asteroidea, Echinodermata).

Ian Hewson,Christopher M Derito,Citlalli A Aquino

doi:10.3390/v12111332

Abstract

Sea star wasting disease (SSWD) is a condition that has affected asteroids for over 120 years, yet mechanistic understanding of this wasting etiology remains elusive. We investigated temporal virome variation in two Pisaster ochraceus specimens that wasted in the absence of external stimuli and two specimens that did not experience SSWD for the duration of our study, and compared viromes of wasting lesion margin tissues to both artificial scar margins and grossly normal tissues over time. Global assembly of all SSWD-affected tissue libraries resulted in 24 viral genome fragments represented in >1 library. Genome fragments mostly matched densoviruses and picornaviruses with fewer matching nodaviruses, and a sobemovirus. Picornavirus-like and densovirus-like genome fragments were most similar to viral genomes recovered in metagenomic study of other marine invertebrates. Read recruitment revealed only two picornavirus-like genome fragments that recruited from only SSWD-affected specimens, but neither was unique to wasting lesions. Wasting lesion margin reads recruited to a greater number of viral genotypes (i.e., richness) than did either scar tissue and grossly normal tissue reads. Taken together, these data suggest that no single viral genome fragment was associated with SSWD. Rather, wasting lesion margins may generally support viral proliferation.

Highlights

Sea star wasting disease (SSWD) describes a condition that has been reported to affect Asteroidea since at least 1898 [1] and is associated with periodic mass mortality episodes, most recently during2013–2014 [2]
Our results demonstrate that there were no viral genome fragments which recruited reads only from wasting lesion margins in SSWD-affected asteroid specimens
We found a progressive enrichment of viral genotypes that recruited sequence reads in lesion margins over time in comparison to artificial scar and grossly normal tissues, suggesting their prominence in prior metaviromic surveys may have been independent of potential pathology

Summary

Introduction

Sea star wasting disease (SSWD) describes a condition that has been reported to affect Asteroidea since at least 1898 [1] and is associated with periodic mass mortality episodes, most recently during2013–2014 [2]. Sea star wasting disease (SSWD) describes a condition that has been reported to affect Asteroidea since at least 1898 [1] and is associated with periodic mass mortality episodes, most recently during. Work suggested association with a densovirus (the Asteroid ambidensovirus-1 [AaV-1]; referred to as the “Sea Star associated Densovirus” [SSaDV]), and experiments which challenged healthy specimens with filtered tissue homogenates generated some SSWD signs [2,4]. Subsequent work found that densoviruses, including AaV-1/SSaDV, occur in diverse asteroid taxa globally [5,6], and are highly prevalent within communities inhabiting the northeast Pacific [6] and northwest Atlantic [7] oceans. Recent investigations suggest that wasting response of asteroids to tissue homogenate challenge could generate via non-pathogenic means (i.e., through organic matter enrichment resulting in suboxic conditions through heterotrophic respiration) [8]. Other proposed mechanisms of wasting, including repeated [9] and monotonic [10] temperature excursions, high pCO2

Methods

Results

Conclusion