Advancements in diagnosis and control measures of viral pathogens in aquaculture: an Indian perspective

Indian aquaculture industry was growing steadily and showed a sixfold growth in production over the last two decades. However, the overall development of aquaculture in India did not reach the levels as projected due to frequent disease outbreaks and related issues. Shrimp and fish are predominantly affected by viruses including white spot syndrome virus, monodon baculovirus, hepatopancreatic parvovirus, viral nervous necrosis, white tail disease, and hypodermal and hematopoietic necrosis baculovirus that cause outbreaks across the countries. Owing to these viral pathogens, the production of aquaculture fishes and crustaceans has dramatically been dropped. There are no specific measures to control these viral infections since it causes mortality at all life stages of cultured aquatic organisms. Early detection of the diseases may be beneficial to prevent the spreading and mass mortality. In India, the Central Institute of Brackish Water Aquaculture has developed a non-invasive diagnostic tool for early and precise detection of monodon baculovirus infection in Indian tiger shrimp Penaeus monodon using SYBR Green-based real-time polymerase chain reaction (PCR) technique. More than twenty-five cell lines from freshwater, brackish water, and marine fish have been developed, characterized, and stored in C. Abdul Hakeem College for research and viral diagnosis. This review reveals the distinctive tools that are being used in aquaculture for the detection of pathogens and preventive measures. Advanced molecular methods such as nested PCR and SYBR Green-based real-time PCR are found to be sensitive and effective for the quantitation. Simple and inexpensive methods such as microscopic evaluation and histopathological analysis detects the progression of the disease. These assays can be used as a diagnostic method for emerging diseases in addition to avoid forthcoming of another.