Distribution of recombinant VP28 protein in tissues and its immunomodulatory effect against white spot syndrome virus in whiteleg shrimp, Litopenaeus vannamei (Boone, 1931)

摘要

The gene encoding VP28 protein of WSSV was cloned into pRSET B vector, and recombinant VP28 (r-VP28) protein was produced in E. coli GJ1158 by induction with NaCl. The r-VP28 protein was purified. The purified r-VP28 protein was injected intramuscularly in Whiteleg shrimp, Litopenaeus vannamei, to study its tissue distribution at different time intervals by ELISA using the antiserum raised against r-VP28, and the results showed the presence of r-VP28 protein in different organs such as heart, hepatopancreas, gill, muscle, and hemolymph. The r-VP28 protein was cleared from all the organs after 264 h post-injection (hpi). Various immunological parameters such as phenoloxidase activity (PO), superoxide anion production, activity of superoxide dismutase, and MDA content were assessed in normal and experimentally r-VP28 protein injected shrimp at different time intervals. The mRNA expression of ten immune-related genes was analyzed in hemocytes, hepatopancreas, and gill by quantitative real-time PCR in order to investigate their expression to r-VP28 injection in L. vannamei, and the results showed the upregulation of expression of immune genes such as PO, cMnSOD, lipopolysaccharides (LPs), BGBP, hemocyanin, crustin, lectin, toll receptor, lysozyme, and tumor necrosis factor receptor-associated factor 6 (TRAF6) in VP28-injected shrimp. The efficacy study revealed that 86.67% survival was observed in shrimp orally treated with r-VP28 protein after WSSV challenge without any clinical sign of WSSV infection till the end of experimental period.