The efficacy of levamisole as an immunostimulant on male and female Oreochromis niloticus challenged by Vibrio alginolyticus

This study demonstrates levamisole effects as an immunestimulator on both gender in vivo infected Oreochromis niloticus fish with Vibrio alginolyticus. 86 naturally infected and apparently health tilapia were sourced from various fish farms in Kafr Elsheikh Governorate, the incidence of V.alginolyticus infection revealed (9.30%). The moribund fish were thoroughly examined to assess clinical, post-mortem, and bacteriological aspects of the disease, Identification of the bacterium included morphological analysis and, sequence of recA gene, submitted Vibrio alginolyticus to the Genebank under accession No OR098883.1. Molecular detection of virulence genes as collagenase was 737 bp , tlh & tdh were 449 & 373 bp, respectively. Isolates were found to be 100% sensitive to Doxycycline and Gentamicin in the antimicrobial susceptibility test, while the strains were 100% highly resistant to Ampicillin.The experimental healthy males and females O. niloticus were divided into four groups (duplicated). Fish G2 and G3 were fed a diet supplemented with levamisole (250mg/kg fish ration) for 60 days. Following the feeding period, groups G3 and G4 were challenged via intraperitoneal injection with a more virulent strain of V. alginolyticus (0.5 mL of 1 × 108 cfu/mL). Morbidity and mortality rates were detected. Lysozyme, total protein and albumin were measured in sera of all groups, and IL10 was assessed from the anterior kidney . Histopathological findings to the testes and ovaries of all groups were explained.