Development of an RT-PCR detection method for mud crab reovirus.

Mud crab reovirus (MCRV) causes high mortality in the cultivated mud crab. To control better an outbreak of this virus, a rapid, specific and sensitive detection method based on RT-PCR was developed. The MCRV detection method was designed based on the one-step and two-step RT-PCR which resulted in the amplification of predicted products of 433 and 304 bp. The method is specific as no cross-reaction was observed between grass carp hemorrhage virus (GCHV), white spot syndrome virus (WSSV), tiger frog virus (TFV), infectious spleen and kidney necrosis virus (ISKNV), fish nervous necrosis virus (NNV) and the muscovy duck virus (MDRV). One-step PCR amplification could detect 10(-8) microg of purified MCRV dsRNA, while two-step PCR amplification could detect 10(-9) microg MCRV dsRNA. At an early stage of infection, MCRV could be detected in the heart, thoracic ganglion, muscle, intestine, gut, hemolymph, gonad and gill, but not in the stomach or hepatopancreas. However, in the moribund mud crabs, MCRV could be detected in all tissues examined.