Evolutionarily divergent nidovirus with an exceptionally large genome identified in Pacific oysters undergoing mass mortality

• 成果类型: Article
• 署名作者: Zhong, Kevin Xu; Chan, Amy M.; Miller, Kristina M.; Saunders, Rob; Suttle, Curtis A.
• 署名单位: University of British Columbia; Fisheries & Oceans Canada; University of British Columbia; University of British Columbia; University of British Columbia
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-14262
• DOI: 10.1073/pnas.2426923122
• 发表日期: 2025-08-04
• 关键词: leucine-rich repeat; crassostrea-gigas; sequence; protein; metagenomics; RECOGNITION

摘要

Metatranscriptomic data from a mass-mortality event of adult Pacific Oysters, Crassostrea (Magallana) gigas, the most widely cultivated shellfish globally, revealed a nidovirus shown to replicate in a bivalve, Pacific Oyster Nidovirus 1 (PONV1). At 64,331 bp of linear bisegmented, positive-sense single-stranded RNA, PONV1 has one of the largest genomes reported for an RNA virus. Moreover, transcriptomic data reveal that many conspecific viruses of PONV1 occur in Pacific oysters from Europe and the Pacific coasts of Asia and North America. PONV1 (tentative species Megarnavirusgigas) and its conspecific viruses represent a putative family, Megarnaviridae, that is widely divergent from other families of nidoviruses, and encodes protein domains likely involved in virus-host interaction that are undescribed for other nidoviruses. Given that PONV1 occurs in diseased Pacific oysters undergoing mass mortality, and that close relatives of PONV1 are widespread globally, it emphasizes the need for caution in the translocation of Pacific oyster spat that routinely occurs. Significance Pacific oysters are the most widely farmed shellfish worldwide, but are increasingly affected by mass-mortality events, often of unknown cause. We present Pacific Oyster Nidovirus 1 (PONV1), identified during a mortality event in farmed Pacific oysters. PONV1 has an exceptionally large genome, is the first nidovirus reported to replicate in bivalves, exhibits a genetic architecture with protein domains not found in other nidoviruses, and represents a newly proposed family, Megarnaviridae. Moreover, PONV1 and its close relatives were detected in Pacific oysters from three continents; thus, if PONV1 causes disease in Pacific oysters, it underlines potential risks from translocation of oysters and oyster-seed. These findings highlight nidovirus diversity and host range, and have potential implications for oyster health and aquaculture.