Immunomodulatory Effect of Purified Exotoxins of Staphylococcus aureus in Association with Bird Flu Virus Vaccine in Broilers

Immunization is the most effective method still used against infectious agents. Although not always, vaccines ineffectiveness is reported enormously against many of the pathogens throughout the world in poultry, particularly in case of killed or sub unit vaccine. The current project is, therefore, carried out as a preliminary study on broiler chickens to investigate the modulation of immune system against avian influenza virus in association with purified Staphylococcus aureus toxoid. After isolation of Gram positive cocci bacteria on mannitol salt agar from raw milk, yogurt and chicken meat were subsequently biochemically characterized by using rapid diagnostic kit. Pure culture of S. aureus was inoculated into digitally controlled bio-fermentor containing mannitol salt broth for production of toxins. Enormous production of bacteria was passed through sequence of filtration system based on 0.45 μm followed by 0.22 μm size. The centrifugation of the filtrate was made at 10,000 rpm for 60 minutes at 5℃ followed by 56,100 rpm for 20 minutes and clear supernatant containing Staphylococcus enterotoxin (SEs) was obtained. Bradford estimation of proteins further provided 305 μg/ml of SEs toxoid. Four types of oil adjuvant avian influenza type H9N2 virus vaccines (without toxoid, 91.5 μg/0.3ml, 22.8 μg/0.3ml and 11.43 μg/0.3ml) were injected into healthy AI H9N2 susceptible broilers and anti-H9N2 HI antibody titers were measured in terms of hemagglutination inhibition test. It was observed that on the 8th day, post vaccination cumulative mean anti AIH9 HI antibody titer of G-1, G-2, G-3, G-4 and G-5 was 3.13 ± 0.406, 5.13 ± 0.246, 3.96 ± 0.159, 3.25 ± 0.237 and 0.78 ± 0.467 respectively. It was found that all the vaccines induced protective titers 18 days’ post vaccination, but vaccine containing 91.5 μg/dose of SEs toxoid showed significantly higher (P < 0.05) immune response as compared to vaccine containing 22.8 μg/dose and 11.43 μg/dose, whereas, vaccines containing SEs toxoid showed better (P < 0.05) anti AIH9 HI antibody titer as compared to vaccine without SEs toxoid. Thus, it is concluded that addition of super antigens of SEs in the form of toxoids, particularly in inactivated vaccines, could be the better choice for modulation of immediate and better immune response in future vaccines technologies.