Can white spot syndrome virus be transmitted through the phytoplankton→rotifer →artemia→shrimp pathway?
The transmission of white spot syndrome virus (WSSV) in the aquatic environment by the pathway of phytoplankton through rotifer to artemia and shrimp was investigated. The phytoplankton Alexandrium tamarense and Alexandrium minutum were co-cultured with adult Fenneropenaeus chinensis infected with WSSV and were assayed by whole cell fluorescence in situ hybridization (WFISH) with probe specific for WSSV labeled with 5-carboxyfluoroscein at 5’-end to study whether they could carry WSSV. Then, the WSSV positive phytoplankton was exposed to the rotifer Brachionus urceu and was assayed by dot blot hybridization with digoxigenin labeled DNA probe. Further experiments were conducted to feed artemia Artemia franciscana with the WSSV positive rotifers and feed juvenile shrimps F. chinensis with the artemia. Our results showed that the pytoplankton were WSSV-positive after 24 h incubation. The dot-blot diagnosis revealed WSSV-positive results in the rotifers exposed to WSSV positive phytoplankton. The cumulative mortality of shrimp and dot blot diagnosis showed that the shrimp can be infected by the food chain of phytoplankton→rotifer→artemia→shrimp.
Key words: White spot syndrome virus (WSSV), whole cell fluorescence in situ hybridization (WFISH), Alexandrium tamarense, Alexandrium minutum, Brachionus urceus, Artemia franciscana, Fenneropenaeus chinensis.