Dietary Intake of Levamisole Improves Non-Specific Immunity and Disease Resistance of Healthy and Aflatoxin-Induced Immunocompromised Rohu, Labeo rohita

Abstract

In order to determine the immunomodulatory effect of dietary intake of levamisole in healthy/aflatoxin B1(AFB)1 treated immunocompromised rohu, Labeo rohita fish were fed diets containing 5 mg levamisole hydrochloride/kg body weight at 3-day intervals on five consecutive occasions for 60 days. The effects of AFBl5 levamisole, and their interactions on non-specific immunity and disease resistance offish were studied. A single intraperitoneal injection of AFB x (1.25 mg/kg body weight) caused significant (P < 0.05) reduction in non-specific immunity as measured through serum bactericidal activity, lysozyme level, neutro-phil oxidative activity, and albumin:globulin as well as reduced protection against Aeromonas hydrophila challenge when compared with control fish not exposed to aflatoxin or levamisole. Feeding of levamisole to healthy fish significantly reduced mortality (25%) when compared with that of the control (55%). Lysozyme level and oxidative radical release were also significantly enhanced in levamisole-fed fish versus controls. When feeding levamisole to AFBj-treated immunocompromised fish, non-specific immunity level as measured through total protein level, al-bumin:globulin, serum bactericidal activity, lysozyme level, neutrophil oxidative radical release, and phagocytic activity were restored. Additionally, mortalities due to A. hydrophila infection were reduced by 45%. Hematocrit, leucocrit levels, and phagocytic index were influenced neither by aflatoxin treatment nor by levamisole feeding. The present results suggest that the addition of levamisole into the diet of rohu grown in stressful conditions or in an immunocompromised state, may increase resistance to infection, reduce fish mortality, and be of economic benefit.