Journal of Antivirals & Antiretrovirals
Open Access

Abstract

Study on Coinfection of Mycoplasma gallisepticum and Low Pathogenic Avian Influenza Virus H9 in Broilers

SM Subtain, Sohail Manzoor, Fraz Munir Khan, Zahid Hussain, Muhammad Mukhtar, Haleema Sadia, Syed Abbas and Iqbal Choudhary

Avian influenza viruses (AIVs) belong to the family Orthomyxoviridae which consists of three genera known as Influenza virus -A, -B and -C. The influenza viruses, which can cause infections in avian species belong to genus influenza virus A which can produce two different types of diseases on the basis of their virulence and pathogenicity. Thus are classified as a highly pathogenic avian influenza virus (HPAIV) and a low pathogenic avian influenza virus (LPAIV). Recent outbreaks of LPAIV H9N2 in Asian countries such as in Pakistan and China revealed that this subtype has become endemic in poultry population of these countries. Meager literature is available about its pathogenicity. This study was made to ascertain the pathogenesis of H9 subtype AIVs in broilers along with most prevalent respiratory pathogen Mycoplasma gallisepticum under field conditions. In first part of study, challenge organisms (H9 virus and Mycoplasma gallisepticum) were isolated from field samples and experimental inoculum was prepared. In second part, pathogenesis of H9 virus in association with M. gallisepticum was carried out under controlled environmental conditions. The virus prevailing in Pakistan was found nonpathogenic as only slight diarrhoea and depression in few birds was seen while clinical signs and lesions produced grossly and microscopically were more severe in form of severe conjunctivitis and facial edema and respiratory involvement with hemorrhagic and pneumonic lungs and degenerative and lytic necrosis in kidneys in birds infected co-infected with H9 virus and Mycoplasma gallisepticum as compared to other groups which were infected with single pathogens. Immunohistochemical detection of viral antigen revealed that replication of virus was more severe in birds infected with H9 virus and Mycoplasma gallisepticum as compared to other groups. In conclusion, the virus subtype H9 circulating in Pakistan is low pathogenic in nature with affinity for respiratory system and urinary system while coinfection with Mycoplasma gallisepticum is the most important factor enhancing the pathogenicity of H9 virus under field conditions.