Betanodavirus infection associated with larval enteropathy as a cause of mortality in cultured gilthead sea bream (Sparus aurata, Linnaeus, 1758)

Abstract Betanodavirus infections have been associated with significant economic losses in Mediterranean marine aquaculture due to viral nervous necrosis (VNN). Recently, RGNNV/SJNNV reassortant betanodavirus has been reported as a possible cause of disease in Sparus aurata. In this study, mortality events occurred in cultured gilthead sea bream from 19 to 26 days of age, coming from an Italian aquaculture farm are described. Samples of diseased larvae were collected and underwent histopathological, bacteriological and virological analyses. Lesions related to VNN and larval enteropathy (LE) were found. The isolates were identified as RGNNV/SJNNV reassortant betanodavirus and Vibrio alginolyticus. With the present study, to our knowledge, we describe for the first time the co-occurrence of VNN and LE, which, in synergy or simultaneously, elicited a mortality outbreak of Sparus aurata larvae.