CHENNAI: In a major breakthrough, the Chennai-based Central Institute of Brackishwater Aquaculture (CIBA) has developed the country's first vaccine for deadly viral nervous necrosis (VNN) disease, which is currently affecting several species of fish.
Scientists say the VNN disease is a serious threat affecting many marine, brackishwater and freshwater fish causing up to 100% mortality in larval and early juvenile stages. The disease is caused by nervous necrosis virus (NNV). Red-spotted grouper nervous necrosis virus (RGNNV) is the only genotype prevalent in India and most other tropical countries. The disease is transmitted both vertically and horizontally. Infected adults remain as carriers and transmit the virus to offspring through eggs. The only practical way to control the disease and prevent vertical transmission is to vaccinate fingerlings and adult fish.
CIBA director KK Vijayan told The New Indian Express that the drug brand named as 'CIBA-Nodavac-R' is an injectable recombinant vaccine which can effectively prevent VNN in fingerlings and prevent vertical transmission in brooders. "The vaccine is safe and efficacious. The vaccine was developed under the consortium research platform on vaccines and diagnostics. The vaccine can be used in all species susceptible to VNN such as Asian seabass, milkfish, grey mullet, mangrove red snapper etc."
Currently, there are only two Asian seabass hatcheries in India, one at the CIBA hatchery in Muttukadu near Chennai and the other at Sirkali operated by the Rajiv Gandhi Centre for Aquaculture under MPEDA. "Asian seabass fish collected from the wild near Nellore in Andhra Pradesh also tested positive for the virus and when used for breeding they transmit the virus to larval stages causing acute mortality in larval stages. Hence it is important to vaccinate the brooders to prevent vertical transmission of the virus," Vijayan said.
Though Asian seabass grow-out farms are not as widespread as shrimp aquaculture, sporadic outbreaks of the disease have been noticed in grow-out farms as farmers do not get the fish tested. Asian seabass farming is picking up and there is a huge demand for the seed from farmers. A few government and private entrepreneurs have signed MoU with CIBA for transfer of technology for Asian seabass hatchery development. Hence Asian seabass farming is expected to go up once these hatcheries come into operation.
M Makesh, principal investigator of the project, said the vaccine is a result of five years of research and rigorous trails. "This is the first vaccine to be released for aquaculture in India and is a recombinant vaccine. An oral vaccine for delivery through feed and an immersion vaccine are also under development."
JK Jena, Deputy Director General (Fisheries) of Indian Council of Agricultural Research, released the recombinant VNN vaccine in a virtual event on Tuesday.