White spot syndrome virus epizootic in cultured Pacific white shrimp Litopenaeus vannamei (Boone) in Taiwan

Abstract

White spot syndrome virus (WSSV) has caused significant losses in shrimp farms worldwide. Between 2004 and 2006, Pacific white shrimp Litopenaeus vannamei (Boone) were collected from 220 farms in Taiwan to determine the prevalence and impact of WSSV infection on the shrimp farm industry. Polymerase chain reaction (PCR) analysis detected WSSV in shrimp from 26% of farms. Juvenile shrimp farms had the highest infection levels (38%; 19/50 farms) and brooder shrimp farms had the lowest (5%; one of 20 farms). The average extent of infection at each farm was as follows for WSSV-positive farms: post-larvae farms, 71%; juvenile farms, 61%; subadult farms, 62%; adult farms, 49%; and brooder farms, 40%. Characteristic white spots, hypertrophied nuclei and basophilic viral inclusion bodies were found in the epithelia of gills and tail fans, appendages, cephalothorax and hepatopancreas, and virions of WSSV were observed. Of shrimp that had WSSV lesions, 100% had lesions on the cephalothorax, 96% in gills and tail fans, 91% on appendages and 17% in the hepatopancreas. WSSV was also detected in copepoda and crustaceans from the shrimp farms. Sequence comparison using the pms146 gene fragment of WSSV showed that isolates from the farms had 99.7-100% nucleotide sequence identity with four strains in the GenBank database--China (AF332093), Taiwan (AF440570 and U50923) and Thailand (AF369029). This is the first broad study of WSSV infection in L. vannamei in Taiwan.

Virulence and genotypes of white spot syndrome virus infecting Pacific white shrimp Litopenaeus vannamei in north‐western Mexico

“…), which has a high virulence and causes great economic losses when it infects Litopenaeus vannamei (Boone) and Penaeus monodon (Fabricius; Cheng et al . ; Dutta et al . ), the two species that currently support the global shrimp aquaculture industry (Walker & Winton ).…”

Detection of viruses in the exotic shrimp Penaeus vannamei Boone, 1931 cultured in India

“…Incidence of WSSV in cultured P. vannamei is reported from Iran (Pazir et al, 2011), Taiwan (Cheng et al, 2013), Equador (Rodriguez et al, 2003) and Indonesia (Ferasyi et al, 2015). WSSV infection has caused mass mortalities of farmed P. vannamei, bringing huge loss to shrimp farmers around the world like Ecuador (Calderon et al, 1999), Brazil (Cavalli et al, 2008) and Iran (Afsharnasab et al, 2009).…”

White spot syndrome virus host range and impact on transmission

“…When infected under culture conditions, WSSV prevalence in L. vannamei ranged from 40 to 71% 124 and was 100% during a WSD outbreak. 124 In contrast, several authors showed that the prevalence of WSSV infection in P. monodon broodstock collected at sea, varied between seasons. [125][126][127] In the Philippines, WSSV prevalence was higher during the dry season (10%) than during the wet season (0.3%), 126 while it was the opposite in Thailand 125 and India.…”