[Pathogenicity of white-spot syndrome virus in Macrobrachium nipponensis via different infection routes]

Macrobrachium nipponensis is delicious and has high economic value, but its susceptibility to white-spot syndrome virus (WSSV) is unknown. Susceptibility, morbidity, and multiplication of WSSV in M. nipponense were studied by epidemiological survey, infection experiment and qPCR. M. nipponense was the natural host of WSSV, and the natural carrying rate was about 8.33%. M. nipponense could be infected with WSSV via oral administration, muscle injection and immersion, and the cumulative infection rate of 10 d exposure was 100%, and the cumulative mortality rates were 100%, 75% and 0%, respectively. The infection of WSSV is fast by muscle injection. The virus content after 5 day's injection is 1 000 times higher than that of the first day of infection, and the mortality rate reached 100% after 8 days. The median lethal dose (LD₅₀) measured as the mortality of infected M. nipponense via injection indicated the LD₅₀ in the concentration of WSSV of 2.71×10⁵ virions/μL. In shrimp farming, M. nipponense can be infected by ingesting WSSV infected shrimp or dead shrimp, and also by soaking in WSSV-containing water and thus become a vector, consequently affecting the spread and pathogenicity of WSSV.