Synchronous Detection of DNA/RNA of Four Shrimp Viruses by Real-time Fluorescence Quantitative RT-PCR

[ Objective] This study aimed to establish a simultaneous detection method of shrimp viruses by real-time fluorescence quantitative RT-PCR, to improve the efficiency of inspection and quarantine. [ Method] A novel real-time fluorescence quantitative RT-PCR assay was established and optimized for simultaneously detecting DNA/RNA of four shrimp viruses （WSSV, IHHNV, TSV and YHV ）. [ Result] The optimized real-time fluorescence quantitative RT-PCR system gener- ated typical amplification curves with high amplification efficiencies （E = 1.06, 1.07, 0.92 and 0.92, respectively）, good hnear relationship （ r = 1 ）, uniform repeatability （ standard deviation = 0.05 - 0.46 ; variation coefficient = 0.26% - 1.62% ） and high sensitivity, exhibiting no significant differences compared with re- al-time fluorescence quantitative PCR （average error of Ct value = 0.04 -0.40; T = 0.53 -2.50; P 〉 0.05 ）. The total detection time was about 1 h. [ Conclusion] The optimized real-time fluorescence quantitative RT-PCR system can be used for rapid detection of WSSV, IHHNV, TSV and YHV.

Shrimp arginine kinase being a binding protein of WSSV envelope protein VP31

Viral entry into the host is the earliest stage of infection in the viral life cycle in which attachment proteins play a key role. VP31(WSV340/WSSV396), an envelope protein of white spot syndrome virus(WSSV), contains an Arg-Gly-Asp(RGD) peptide domain known as a cellular attachment site. At present, the process of VP31 interacting with shrimp host cells has not been explored. Therefore, the VP31 gene was cloned into p ET30a(+), expressed in Escherichia coli strain BL21 and purifi ed with immobilized metal ion affi nity chromatography. Four gill cellular proteins of shrimp( Fenneropenaeus c hinensis) were pulled down by an affi nity column coupled with recombinant VP31(r VP31), and the amino acid sequences were identifi ed with MALDI-TOF/TOF mass spectrometry. Hemocyanin, beta-actin, arginine kinase(AK), and an unknown protein were suggested as the putative VP31 receptor proteins. SDS-PAGE showed that AK is the predominant binding protein of VP31. An i n vitro binding activity experiment indicated that recombinant AK's(r AK) binding activity with r VP31 is comparable to that with the same amount of WSSV. These results suggested that AK, as a member of the phosphagen kinase family, plays a role in WSSV infection. This is the fi rst evidence showing that AK is a binding protein of VP31. Further studies on this topic will elucidate WSSV infection mechanism in the future.