The role of trans-vp28 gene Synechocystis sp. PCC6803 in the defense against white spot syndrome virus (WSSV)

To develop a more comprehensive understanding of the efficacy of trans-vp28 gene Synechocystis sp. PCC6803 and its effect on white spot syndrome virus (WSSV), this study investigated the activities of several immune-related enzymes including acid phosphatase (ACP), alkaline phosphatase (AKP) and peroxidase (POD) in muscle and hepatopancreas of Penaeus vannamei, and conducted a more intuitive analysis from the perspective of histopathology. P. vannamei were orally fed trans-vp28 gene Synechocystis sp. PCC6803 for 10 days and then challenged with WSSV. The cumulative survival rate, activities of enzymes and the histopathology were determined. The results show that on the 7th day after challenge, the survival rate of the experimental group (i.e., challenged and fed mutant Synechocystis sp. cells) and the wild type group (i.e., challenged and fed wild type Synechocystis sp. cells) were 80.2% and 26.4%, respectively, while all shrimp in the positive control group (i.e., challenged, but no vaccination) died. There was no death in the negative control group (i.e., no vaccination or challenge). After immunization, the activities of ACP, AKP and POD in both tissues were the highest in the experimental group. After challenge, the final enzyme activities of the three enzymes in the experimental group were higher than those in the positive control group and the wild type group. The results of histopathology showed that muscle fibers in the negative control group were neatly arranged with numerous and evenly distributed nuclei, while muscle fibers in the positive control group and the wild type group were wavy. The nuclei of muscle fibers in the positive control group were also swollen and unevenly distributed. The nuclei of the muscle fibers in the experimental group were slightly clustered, and the muscle fibers were arranged neatly. In hepatopancreas samples, narrow cell gaps and regular nuclei were observed in the negative control group. The connective tissue and cell walls were severely damaged and the cells were degraded in the positive control group. However, although the connective tissue of the experimental group was slightly loose, the cells were orderly and the nuclei were arranged neatly. These results indicated that trans-vp28 gene Synechocystis sp. PCC6803 could improve the immunity of shrimp.

Automated summary

The study investigated the efficacy of trans-vp28 gene Synechocystis sp. PCC6803 on Penaeus vannamei infected with white spot syndrome virus (WSSV). The results revealed that the experimental group showed a significantly higher survival rate after challenge, higher immune-related enzyme activities in tissues, and more normal tissue structure based on histopathology analysis.