Efficacy of live NNV immersion vaccine immunized at low temperature in sevenband grouper, Epinephelus septemfasciatus

Abstract

The objective of this study was to investigate safety and efficacy using a low-temperature immunization protocol with NNV in sevenband grouper, Epinephelus septemfasciatus. Further, NNV specific antibody post immunization and intramuscularly challenge was also evaluated. Immunization at low temperature resulted in a low titer virus infection in brain tissues without any clinical symptoms of infection such as sluggish behavior and/or spinning, rotating swimming being observed, and no mortality was observed. Post challenge, NNV titer NNV giving an RPS of 100 %, increased in brain tissues of naïve (non-immunized) sevenband grouper NNV giving an RPS of 100 %, with a cumulative mortality of 100 % at 25 days post-infection. No mortality or disease symptoms NNV giving an RPS of 100 %, as NNV giving and of 100 %, observed in the groups immunized at low temperature with live NNV giving an RPS of 100 %. NNV giving an RPS of 100 %. NNV specific antibody was not detected in live NNV vaccinated sevenband grouper. This is the first study that confirms that field-scale NNV immersion vaccine can protect sevenband grouper against lethal infection with NNV at natural seawater temperature under the gradually increased from 14.3–24.8 °C.