Experimental inoculation of oriental river prawn Macrobrachium nipponense with white spot syndrome virus (WSSV)

The oriental river prawn Macrobrachium nipponense is an economically important species that is widely farmed in China. White spot syndrome virus (WSSV) is one of the most devastating pathogens of the cultured shrimp Litopenaeus vannamei, responsible for massive loss of its commercial products worldwide. We investigated the infectivity and pathogenicity of WSSV in adult M. nipponense using standardized conditions for L. vannamei. The median lethal dose of WSSV in adult M. nipponense was 103.84±0.06 copies g-1, which was about 1000-fold higher than in L. vannamei (100.59±0.22 copies g-1). WSSV was detected by 2-step PCR in the gills, hepatopancreas, muscle, stomach, heart, gut, nerve, integument, pereopod, eyestalk, testis, and ovary of experimentally infected dead M. nipponense. Lesions were observed histologically following WSSV injection, showing basophilic intranuclear inclusion bodies in the hepatopancreas and subsequently in the gills. The clearance of WSSV was observed in hepatopancreas and gills at 48 and 96 h post-inoculation, respectively. No histological lesions were detected in muscle from 0-96 h post-injection. The results show that the oriental river prawn M. nipponense can be infected by WSSV and the infections are self limiting over time; therefore, M. nipponense may serve as a useful model for studying resistance to WSSV.