The protective efficacy of forty outer membrane proteins based DNA vaccines against Aeromonas hydrophila in zebrafish

Abstract

It is well known that the outer membrane proteins (OMPs) of Gram-negative bacteria are potential vaccine candidates against bacterial infections, whereas systematic research on the protective efficacy of OMP components is rarely reported. In the present study, we constructed forty OMP recombinant plasmids of Aeromonas hydrophila and evaluated their immune protection against A. hydrophila infection in zebrafish. Our results showed that the transcriptions of many immune-related genes were induced after DNA vaccine immunization. The nine DNA vaccines (pcDNA3.1 (+) plasmid carrying recombinant rAHA_2145, rpilQ, rAHA_1130, rtamA, rAHA_2144, rhgpB, rAHA_3766, rgspD and rAHA_2785 genes) enhanced the survival rates of zebrafish to higher than 50% after challenged with virulent A. hydrophila. Furthermore, after the prime-boost vaccination, these nine DNA vaccines could enhance the host immune response and relative percent survival rates (RPSs) of zebrafish to higher than 60%. Taken together, these OMPs-based DNA vaccines can elicit immune responses and enhance immune protection in zebrafish against A. hydrophila infection, especially the DNA vaccines encoded by rAHA_2144 and rpilQ, which RPSs of zebrafish were 82.4% and 70.2%, respectively after the prime-boost vaccination.