Viral nervous necrosis Mortality in Wild Grouper from Central and Western Algeria

Viral nervous necrosis (VNN) is a disease caused by Betanodavirus that leads to outbreaks mortality in wild or farmed marine fish. This study aimed to investigate the presence of Betanodavirus in grouper from different sites along the Algerian coast and to characterize the isolates using molecular tools. A total of twenty-three individuals were examined: one dusky grouper (Epinephelus marginatus Lowe, 1834) and twenty-two goldblotch groupers (Epinephelus costae Steindachner, 1878). The RT-qPCR detected the presence of VNN in seven individuals of Epinephelus costae, three from the center of the Algerian coast (two from Algiers and one from Gouraya) and four from the west (Mostaganem). Phylogenetic analyses of the partial sequences of RNA1 and RNA2 viral genome fragments revealed the presence of the red-spotted grouper nervous necrosis virus (RGNNV) genotype, closely related to strains previously detected in Algerian groupers and wild grouper from Spain. The results of this study confirm further that VNN disease is endemic among grouper populations in Algeria, which could be a determining factor in the observed decline of this species.