White Spot Syndrome Virus (WSSV)

White spot syndrome virus (WSSV) is a highly infectious virus causing 100% mortality in commercially farmed crustaceans within a few days. The viral epizootics result in substantial financial loss to the farmers, threatening the sustainability of the shrimp industry worldwide. WSSV is a bacilliform, non-occluded, enveloped virus with a circular dsDNA genome and belongs to the family Nimaviridae. It is one of the largest known animal viruses. The white spot disease (WSD), caused by WSSV, is manifested in the form of white spots/patches underneath the exoskeleton of shrimp, along with other clinical signs. A range of highly sensitive and specific diagnostic techniques have been developed for the detection and quantification of the virus. The virus has been reported in several Southeast Asian countries, North American and Latin American countries, Africa and Australia. Various geographical isolates with genotypic variability have been identified in the virus. The virus possesses a wide host range and affects all life stages of farmed penaeid shrimps. Additionally, it affects several species of prawns, crabs, crayfish and other aquatic invertebrates. The transmission of the virus has been reported to be through horizontal and vertical means. Several methods, including gross clinical signs, histopathological manifestations, in situ hybridization, and immunological and DNA-based molecular methods, were established for the laboratory and field-level diagnosis of WSSV. Prophylactic measures against WSSV have been explored, including diverse vaccination methods and RNAi technology targeting different viral genes. Stocking specific pathogen-free (SPF) post-larvae and implementing stringent biosecurity measures at farming facilities are crucial to prevent the introduction and spread of WSSV.