Evaluation in broilers of aerosolized nanoparticles vaccine encapsulating imuno-stimulant and antigens of avian influenza virus/Mycoplasma gallisepticum

Abstract

The global prevalence of economic primary infection of poultry by H9N2 virus, including the Lineage A, panzootic group ME1, predominant in many ME countries including KSA, and associated with secondary infection by Mycoplasma gallisepticum (MG). This research evaluated in broilers the immunity and protection induced by aerosolization of liposomal nanoparticles vaccine, encapsulating antigens of H9N2 virus (Lineage A, panzootic group ME1) and MG (R-strain), with or without the incorporation of Echinacea extract (EE) immuno-stimulant. Six treatments (TRTs) of broilers were included in the experimental design, with three replicate pens/TRT and stocking of 20 day-old birds/replicate. Birds in TRT 1 received at 14 and 21 d of age the aerosolized nanoparticles, incorporating the antigens and devoid of immuno-stimulant, followed by intra-tracheal challenge at 28 d of age with viable H9N2 and MG; Birds of TRT 2 received aerosolized nanoparticles, incorporating only the EE and challenged similarly; TRT 3 received the aerosolized nanoparticles, incorporating both the antigens and EE followed by challenge; TRT 4 were only challenged(Positive Controls) ; TRT 5 received both the antigens and EE incorporated in aerosolized nanoparticles, and deprived of challenge; TRT 6 were deprived of vaccination and of challenge (Negative Controls). The tracheobronchial washings of TRT 3 showed the highest significant mean levels of each of IgA and IgG specific to H9N2 and MG, associated with lowest tracheal MG colonization, tracheal H9N2 recovery, tracheal histopathologic lesions, mortality, and best performance in BW and feed conversion compared to all other challenged birds of the different treatments (P<0.05). However, broilers free from challenge with MG and H9N2 (TRTs 5 and 6) had the lowest mortality and tracheal lesions, and the highest production performance. The aerosolization of liposomal nanoparticles, encapsulating antigens of H9N2 and MG and EE resulted in enough local immunity for protection of broilers against infection and lesions by the two causative agents, and for attaining the highest production performance in challenged birds. The vaccination by the antigens and EE to birds deprived of challenge had its apparent positive effect on production, an indication of the safety of the killed vaccine on broilers.