New Approach for Protection of Chickens against Mycoplasma Gallisepticum and Avian Influenza H9 Disease Using a Nano-Oil Adjuvanted Combined Inactivated Vaccine

AbstractMycoplasma gallisepticum is the main agent of chronic respiratory disease and also it helps greatly co-infection with low pathogenic avian Influenza (H9N2) in chickens. The protective efficacy of a combined inactivated vaccine, formulated with a locally prepared low-pathogenic avian influenza (LPAI) subtype H9N2 and Mycoplasma gallisepticum (MG), was evaluated in specific pathogen-free (SPF) chickens using nasal and subcutaneous routes. The prepared combined vaccine exhibited no adverse local or systemic reactions and was free from bacterial or fungal contamination. The immune response to LPAI H9N2 and MG was assessed using the hemagglutination inhibition (HI) and enzyme-linked immunosorbent assay (ELISA) tests. The results demonstrated that the vaccine induced a high level of seroconversion via both routes, beginning after the 2nd WPV and reaching peak at the 4th and 5th WPV. Antibody titers in chickens vaccinated via the subcutaneous (SC) route showed a stronger immune response compared to those vaccinated via the intranasal (IN) route. The mean reduction of viral shedding titers of LPAI H9N2 was done in SPF Embryonated chicken eggs (ECE) and it was found that 2.35 and 2 log₁₀ EID₅₀, using SC and IN routes respectively. Additionally, the challenged chicken groups against virulent MG strain after 4th WPV exhibited satisfactory protection, with protection rates of 90% and 80% for both routes, respectively. In conclusion, immunization with the inactivated combined vaccine adjuvanted with Montanide™ IMS 1313 N VG PR induced early and strong seroconversion, providing satisfactory protection compared to the control group. Adaptive immunity elicited via the SC route resulted in a higher immune response and stronger protection compared to the mucosal immunity induced via the IN route. The prepared vaccine is considered a promising vaccine when used to achieve protection against both MG and H9N2.Key Words: Low Pathogenic Avian Influenza (H9N2), Mycoplasma gallisepticum, Inactivated combined vaccine, Nano-oil emulsion.