Comparative Pathology of Experimental Avibacterium Paragallinarum Infection in Chicken and Japanese Quail

Abstract

IntroductionAvibacterium paragallinarum (Av.paragallinarum) is the causative agent of infectious coryza (IC) in chicken, an economically devastating disease of poultry industry. Despite the availability of effective vaccines against IC, the infection is rampant in unorganized poultry sector. Moreover, reports of wider host susceptibility in poultry farms and under field conditions are also emerging. Av.paragallinarum affects the upper respiratory tract of birds and has a predilection for the nasal turbinates. However, no study has systematically evaluated the early pathological changes and mucosal immune responses during Av. paragallinarum infection in the nasal turbinates of chicken. Furthermore, the use of Japanese quail as an alternate experimental animal model than chicken in IC remain unexplored. Here, we examined clinical signs, gross and histopathological changes at the nasal turbinates following experimental Av. paragallinarum infection in chicken and Japanese quail. MethodsWe developed a comprehensive scoring system for recording gross and histopathologic lesions during infection. ResultsOur data show that chicken have a higher susceptibility to Av.paragallinarum infection than the Japanese quail. Japanese quail had significantly lower gross as well as histopathology score in nasal turbinates as compared to infected chicken. Importantly, chicken at an early age i.e. 2.5 weeks were able to induce mucosal immune responses against Av. paragallinarum infection. ConclusionOur findings suggest that there are demonstrable differences in the disease pathology and host immune response to Av. paragallinarum infection in chicken and Japanese quail and warrant further investigation for the use of Japanese quail as an animal model for IC.