The production of anti-Vibrio harveyi egg yolk immunoglobulin and evaluation of its stability and neutralisation efficacy

In order to replace the antibiotic treatment for control of Vibrio harveyi, a causal agent of luminous disease in Black tiger shrimp, anti-V. harveyi IgY was produced and showed its potential in our preliminary study. However, for further use as feed additive, the IgY stability should be evaluated. The titre of specific IgY was enhanced with an immunostimulant, C-phosphate guanosine oligodeoxynucleotide (CpG-ODN). IgY was stable at natural pH while the activity was decreased below pH 4 or above pH 10. The supplementation of 30% sorbitol significantly enhanced the IgY stability at tested temperatures in excess of 70°C. The activity of IgY remained at 9 and 94% after 4 h incubation in simulated gastric and intestinal fluids, respectively. A storage temperature at −20°C was found to be the best condition. IgY at the concentrations of 1, 5 and 10 mg/ml efficiently inhibited V. harveyi in vitro within 24 h after exposure.