Abstract: 【Objective】 The codon of the novel lectin PcLT gene sequence of Procambarus clarkii was optimized，and the physicochemical properties and structure of the protein encoded by this sequence were analyzed using bioinformatics software.The recombinant PcLT protein was expressed through the prokaryotic expression system,and the application effect in white spot syndrome virus disease of shrimp was evaluated. 【Method】 The PcLT gene sequence was obtained from GenBank (accession No.：JQ670880.1),optimized according to the codon preference of Escherichia coli.The physicochemical properties,secondary structure and tertiary structure of the protein were predicted by bioinformatics software.The PcLT gene fragment was ligated with the pET-32a(＋) vector by T4 ligase to construct the recombinant plasmid pET32a-PcLT.The recombinant protein PcLT was expressed in prokaryotic expression system of Escherichia coli BL21 (DE3).The protein was purified by Ni-column affinity chromatography.The recombinant protein PcLT was mixed with feed and fed to diseased shrimp infected with White spot syndrome virus (WSSV)，and to detect its application effect. 【Result】 PcLT gene encoded 169 amino acids，and PcLT protein was a stable and hydrophobic protein with a theoretical isoelectric point of 4.17 and a solubility of 0.645.It was a non-transmembrane protein,containing 27 phosphorylation sites and a secretory signal peptide.The secondary structure of PcLT protein mainly included alpha helix (26.63%),extended chain (21.30%) and random coil (52.07%),and the tertiary structure was mainly random coil.The recombinant plasmid pET32a-PcLT was successfully constructed,and the recombinant protein PcLT was expressed and purified.The molecular mass of PCLT protein was 33 ku.After feeding the shrimp with 100 mL PcLT recombinant protein for 5 days,the copy number of WSSV in the shrimp decreased,the virus detection result turned from positive to negative,and the shrimp ate the feed normally. 【Conclusion】 The recombinant protein PcLT was successfully expressed,and it had a good effect in the application against WSSV.This results provided a theoretical basis for the prevention and treatment of WSSV in shrimp aquaculture and related research.

Key words: Procambarus clarkii; novel lectin PcLT; White spot syndrome virus