Contribution of Viral Genomic Diversity to Oyster Susceptibility in the Pacific Oyster Mortality Syndrome

• Published in: Frontiers in Microbiology
• Main Authors: Jean Delmotte, Cristian Chaparro, Richard Galinier, Julien de Lorgeril, Bruno Petton, Pierre-Louis Stenger, Jeremie Vidal-Dupiol, Delphine Destoumieux-Garzon, Yannick Gueguen, Caroline Montagnani, Jean-Michel Escoubas, Guillaume Mitta
• Format: Article in Journal/Newspaper
• Language: English
• Published: Frontiers Media S.A. 2020
• Subjects: Crassostrea gigas; herpesvirus diversity; genotype-genotype interactions; oyster genetic background; viral populations; Microbiology; QR1-502; Pacific; Pacific oyster
• Online Access: https://doi.org/10.3389/fmicb.2020.01579; https://doaj.org/article/c285e0c500754cbe8ec79d4f15be88cc

Juvenile Pacific oysters (Crassostrea gigas) are subjected to recurrent episodes of mass mortalities that constitute a threat for the oyster industry. This mortality syndrome named “Pacific Oyster Mortality Syndrome” (POMS) is a polymicrobial disease whose pathogenesis is initiated by a primary infection by a variant of an Ostreid herpes virus named OsHV-1 μVar. The characterization of the OsHV-1 genome during different disease outbreaks occurring in different geographic areas has revealed the existence of a genomic diversity for OsHV-1 μVar. However, the biological significance of this diversity is still poorly understood. To go further in understanding the consequences of OsHV-1 diversity on POMS, we challenged five biparental families of oysters to two different infectious environments on the French coasts (Atlantic and Mediterranean). We observed that the susceptibility to POMS can be different among families within the same environment but also for the same family between the two environments. Viral diversity analysis revealed that Atlantic and Mediterranean POMS are caused by two distinct viral populations. Moreover, we observed that different oyster families are infected by distinct viral populations within a same infectious environment. Altogether these results suggest that the co-evolutionary processes at play between OsHV-1 μVar and oyster populations have selected a viral diversity that could facilitate the infection process and the transmission in oyster populations. These new data must be taken into account in the development of novel selective breeding programs better adapted to the oyster culture environment.