Construction and application of easy-to-detect cyanobacteria with vp28 gene

White Spot Syndrome Virus (WSSV) is the most harmful and pathogenic infectious agent in shrimp aquaculture. Vp28, a protein used to protect hosts against this virus, has successfully been expressed in nine hosts since 2004; however, to date, it has not been used commercially. We constructed transgenic Synechococcus elongatus PCC 7942 expressing vp28 and enhanced green fluorescent protein ( egfp ) genes simultaneously to enable the easy detection of vp28 expression. GFP has been expressed in cyanobacteria previously and was used in this study to construct transgenic cyanobacteria that can easily be detected. The optimal growth conditions for the transgenic cyanobacteria were determined using a liquid-phase oxygen electrode. At the optimum light intensity, the net photosynthetic rate of the transgenic cyanobacteria increased by 12.6% compared with that of the wild-type. Furthermore, Synechococcus sp. PCC 7942 harboring vp28 and vp28 - egfp were fed to shrimp in order to protect them against WSSV infection. The cumulative survival rate of the groups fed with transgenic cyanobacteria was 75%.