Inactivated Whole Vaccine Inhibits Lethal Vibrio harveyi Infection in Oplegnathus punctatus

Aquaculture plays a key role in food production globally and provides valuable source of protein nutrition, addressing worldwide growing demand. Oplegnathus punctatus (spotted knifejaw) is an economically important fish species with high market value Previous studies on O. focused mainly gonadal development, chromosomal microstructure, selective breeding, characterization immune genes, viral diseases. There no published scientific research regarding vibriosis this species. In study, two potential pathogenic bacteria, Vibrio harveyi Enterococcus gallinarum, were isolated from moribund cultured punctatus. The sequence the universal 16S rDNA gene was used to identify bacteria punctatus, morphological assessments API20E tests bacterial isolates conducted verify identity biochemical characteristics isolates. Injection E. gallinarum did not lead mortality during 21 days observation. contrast, died overnight when challenged V. at 1.25 × 105 CFU/g body weight, suggesting that cause death infection. Antimicrobial sensitivity analyses revealed strain NTOU sensitive flumequine, doxycycline, oxolinic acid, amoxycillin. Importantly, we demonstrated for first time intraperitoneal administration inactivated whole-cell vaccine resulted level protection against infection