White Spot Syndrome Virus-A Threat To Sustainable Shrimp Cultivation

Abstract

White Spot Syndrome Virus (WSSV) causes a serious contagious disease capable of causing 100% mortality in shrimps and many other crustaceans. Since the first outbreak of this disease in China in 1992, it has gradually spread to all parts of the world. This is the most devastating crustacean disease which threatens aquaculture, globally causing enormous economic losses. WSSV is an enveloped bacilliform rod shaped virus with a large genome of 300 kb ds DNA and has been assigned the genus-Whispovirus in the family Nimaviridae. Symptoms of the disease are manifested as white round spots on cuticular epithelium and carapace with reddish discoloration on the body and appendages of shrimps. The virus causes severe pathological damage to gills, stomach, heart, lymphoid organs, hematopoietic and muscle tissues. Diagnosis of WSSV is based on histopathological, immunological and molecular tests. The virus has a very wide host range and transmission is by both vertical (from infected brood stock to post larvae) and horizontal (by carrier animals, cannibalism and predation of infected organisms) routes. This review details the geographical appearance cum establishment, viral characteristics, genomic properties, pathological, transmission and epidemiological features of this disease. This paper also outlines the ways to prevent and manage the disease burden posed by WSSV to aquaculture. The latest technological control measures deploying vaccines, RNAi and  CRISPR-Cas approaches have also been discussed.