This study shows that WSSV infection in kuruma shrimp is temperature dependent and shrimp was highly susceptible to WSSV infection at around 25oC. Low temperature (15oC) reduces rather than stop WSSV replication in infected shrimp. Shrimp at 15oC may act a carrier of WSSV and could spread the disease if water temperature is increased. | J. Sci. & Devel. 2015, Vol. 13, No. 8: 1405-1414 Tạp chí Khoa học và Phát triển 2015, tập 13, số 8: 1405-1414 EFFECT OF LOW WATER TEMPERATURE ON THE PATHOGENICITY OF WHITE SPOT SYNDROME VIRUS (WSSV) IN KURUMA SHRIMP (Marsupenaeus japonicus) Dang Thi Lua1*, Ikuo Hirono2 1 Center for Environment and Disease Monitoring in Aquaculture, Research Institute for Aquaculture Viet Nam; 2Laboratory of Genome Science, Tokyo University of Marine Science and Technology, Japan Email*: danglua@ Received date: Accepted date: ABSTRACT White spot syndrome virus (WSSV) is a highly lethal, stress-dependent virus which causes serious economic losses for shrimp farming worldwide. Measures that boost/stimulate the shrimp immune system to control WSSV are not yet available and, therefore, environmental management to minimize stress plays a major role in disease prevention. This study was performed to investigate the effect of water temperature on WSSV infectivity, and to evaluate the effect of low temperature on pathogenicity of WSSV in kuruma shrimp, Marsupenaeus japonicus. The results showed that the earliest and highest mortality patterns, culminating with 100% mortalities at 7 ., were o observed when shrimp was continuously kept at 25 C, followed by those of shrimp was continuously kept at o o temperature of 20 C. The best survival (80%) was observed when shrimp continuously kept at 15 C. The delayed o o and reduced mortalities were observed when shrimp were transferred from 25 C to 15 C compared to shrimp held at o 25 C before and after WSSV challenge. In contrast, the increased mortalities were observed in shrimp shifted from o o o 15 C to 25 C when compared to mortalities of shrimp continuously held at 15 C. PCR and RT-PCR provided evidences confirming and supporting the mortality assay. This study shows that WSSV infection in kuruma shrimp is o temperature dependent and shrimp was highly susceptible to WSSV infection at around
