Isolation of Nervous Necrosis Virus from Hybrid Grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂) Cultured in Guangxi, China

Abstract

Outbreaks of suspected viral nervous necrosis emerged in cultured groupers in Guangxi, China in August 2018. ​Histopathology showed severe vacuolation in the brain tissue of the diseased juvenile hybrid grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂). ​A nervous necrosis virus (NNV) was isolated from pooled sample of the brain and eyes using a grouper cell line EAGB. ​Cytopathic effect with multiple cytoplasmic vacuolation cells developed in EAGB cells. ​The coat protein gene sequence of the isolate (GNNV-Gx) showed that it belonged to RGNNV genotype and was most closely related to that of a tiger grouper NNV registered in GenBank. ​The infectivity of the isolate decreased remarkably at pH 3 and pH 10 and was susceptible to 60°C.