Immunogenicity and protective efficacy of a major White Spot Syndrome Virus (WSSV) envelope protein VP24 expressed in Escherichia coli against WSSV

•Production and purification of WSSV recombinant envelope protein VP24 in E. coli.•Oral administration of rVP24 protects shrimp juveniles from WSSV.•Downregulation of WSSV genes dnapol, lat1 and vp28 in the vaccinated animals.•Differential expression of immune genes after rVP24 administration.

The study reports cloning, expression and characterization of immunogenic activity of VP24, a major envelope protein of White Spot Syndrome Virus (WSSV). His-tagged VP24 was expressed as truncated protein and purified from inclusion bodies by metal affinity chromatography under denaturing conditions. The ability to confer protection from WSSV by oral administration of recombinant viral protein (rVP24) was examined in black tiger shrimp Penaeus monodon (P. monodon) juveniles (advanced post larvae). Animals were fed with rVP24 for 10 days, orally challenged with WSSV and assayed for expression of viral genes and shrimp immune genes on the 2nd, 5th and 8th days of challenge. The survival of juvenile shrimps in the vaccinated and challenged group was significantly higher compared to the unvaccinated and challenged group with lesser viral gene expression (DNA polymerase, latency 1 and vp28). Analysis of immune gene expression showed upregulation of syntenin and down regulation of STAT, Rab 7 and caspase during the experimental period. This study points to the feasibility of using rVP24 as candidate vaccine in P. monodon against WSSV.

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