Title : First report of detection and confirmed infectivity of white spot syndrome virus (WSSV) in crayfish imported to Korea
Abstract:
White spot syndrome virus (WSSV) is a highly virulent viruses affects crustaceans, causing up to severe mortality within 3–10 days of symptom onset, resulting a substantial losses in the global shrimp industry. Recently, WSSV was detected in imported whiteleg shrimp (Penaeus vannamei) from Vietnam to Korea, highlighting the need for strict monitoring of imported crustaceans. This study aims to detect the presence of WSSV in the freshwater crayfish imported to Korea, and assess its the potential infectivity. The samples are two species of crayfish, Cherax quadricarinatus (total samples of 320 in eight batches) imported from Indonesia and Procambarus clarkii (total samples of 40 in two batches) imported from China, obtained from fishery markets in Korea. Five representative samples per batch (N = 50) were screened for WSSV using PCR assay. The virus was detected in five C. quadricarinatus samples and one P. clarkii sample.
Among the WSSV-positive samples, the highest virus titer (corresponding to the load of 4.93 × 105–8.36 ×106 copies/μL) was detected in the P. clarkii samples, while C. quadricarinatus samples showed a comparatively lower titer (corresponding to the load of 5.94 × 101–3.86 × 105 copies/μL). The virus infectivity test was conducted by feeding feeding WSSV-positive crayfish tissue (3.46 × 107 WSSV copies/μL) to P. vannamei (N = 42) at 5% shrimp biomass. The test confirmed WSSV infection in the shrimp, indicating that the virus-infected frozen crayfish could serve as a potential transmission source of viral disease. This is the first report of confirmed infectivity of WSSV from the crayfish imported into Korea, highlighting the importance of accurate and strict monitoring of crustacean viruses in imported crustaceans from foreign countries. In conclusion, the detection of WSSV in crayfish imported to Korea and its infectivity in shrimp emphasizes the need for strict monitoring of imported crustaceans to prevent the spread of viral diseases in aquaculture. This study provides valuable information to policymakers, importers, and regulators in the shrimp industry, enabling them to make informed decisions regarding the importation and management of crustaceans. The findings of this research can also serve as a foundation for further studies on WSSV infectivity and management strategies in crustacean
