Detection of viruses in Penaeus monodon from India showing signs of slow growth syndrome

The presence of viruses implicated in slow growth of Penaeus monodon, hepatopancreatic parvovirus (HPV), monodon baculovirus (MBV), infectious hypodermal and hematopoietic necrosis virus (IHHNV) and Laem–Singh virus (LSNV) was studied by polymerase chain reaction (PCR) in 72 P. monodon samples, which showed slow growth rate. The prevalence of IHHNV was highest 18/72 (25%) followed by HPV 5/72 (6.9%), LSNV 3/72 (4.2%) and MBV 3/72 (4.2%). Further, 20/72 (27.7%) samples were positive for WSSV and 18/72 (25%) had clinical conditions typical of monodon slow growth syndrome (MSGS) of which eight samples had IHHNV, two had LSNV and remaining eight were free from all known slow growth viruses. In a hatchery based study, 71 post larval samples were analysed and the incidence of IHHNV was highest 44/71 (61.9%) followed by MBV 7/71 (9.8%), HPV 6/71 (8.4%) and WSSV 2/71 (2.8%). Hatchery rearing of IHHNV infected P. monodon nauplii up to 50 days confirmed the virus to be responsible for slow growth. The study suggests the presence of IHHNV in India and indicates that this virus could be one of the causes of slow growth in cultured P. monodon.