Virus detection in diseased and healthy fish and oysters from an Indonesian aquaculture site: Double infection of viral nervous necrosis virus (VNNV) and marine birnavirus (MABV)

In the south Sumatra region of Indonesia, tiger grouper, Epinephelus fuscoguttatus, and humpbuck grouper, Cromileptes altivelis, are commercially important fish species. Recently, however, mass mortalities of the two species have occurred in the region and the cause of these mortalities has not been clarified. We surveyed the distribution of fish viruses including viral nervous necrosis virus (VNNV), marine birnavirus (MABV) and red seabream iridovirus (RSIV) in the two grouper species and MABV in silver lip oyster, Pinctada maxima, by PCR. VNNV was detected from both healthy and diseased groupers whereas MABV was only detected in diseased groupers, suggesting that the mass mortalities of the two grouper species were caused by co-infection of VNNV and MABV. PCR product of RSIV was not observed in any fish samples. In addition, MABV was not detected in silver lip oysters from both healthy and those exhibiting poor growth.