Studies on the rotifer (Brachionus urceus Linnaeus, 1758) as a vector in white spot syndrome virus (WSSV) transmission

The rotifer Brachionus urceus (Linnaeus, 1758) was experimentally infected with the white spot syndrome virus (WSSV) by the virus–phytoplankton adhesion route in order to assess the possibility of rotifer acting as a vector of WSSV to infect the shrimp Fenneropenaeus chinensis (Osbeck, 1765) larvae at zoea stage III. The nested-PCR test revealed WSSV-positive results in the rotifers exposed to WSSV by the virus–phytoplankton adhesion route. Among 10 replicates in the infection treatment, 40% of F. chinensis larvae became WSSV-positive when fed with WSSV-positive rotifers, whereas all were WSSV-negative for F. chinensis when fed with WSSV-free rotifers. Though the mortality of shrimp larvae in the infection treatment (39.47 ± 15.44%) was higher than that in the control treatment (34.67 ± 15.11%), there was no significant difference in the mortality between them (P > 0.05). These results indicated that the rotifer could serve as a vector in WSSV transmission when ingested.