Comparative molecular characterization, pathogenicity and seroprevalence of avian influenza virus H9N2 in commercial and backyard poultry flocks. (June 2019)

• Record Type: Journal Article
• Authors: Eladl, Abdelfattah H.; Alzayat, Asmaa A.; Ali, Hanaa S.; Fahmy, Hanan A.; Ellakany, Hany F.
• Is Part Of: Comparative immunology, microbiology and infectious diseases. Volume 64(2019)
• Page Start: 81
• Page End: 89
• Publication Date: 2019-06
• Subjects: Molecular characterization -- AIV-H9N2 -- Pathogenicity -- Seroprevalence; Communicable diseases in animals -- Periodicals; Veterinary immunology -- Periodicals; Veterinary microbiology -- Periodicals; Immunology -- Periodicals; Microbiology -- Periodicals; Communicable diseases -- Periodicals; Communicable Diseases -- immunology -- Periodicals; Communicable Diseases -- veterinary -- Periodicals; Allergy and Immunology -- Periodicals; Microbiology -- Periodicals; Veterinary Medicine -- Periodicals; Immunologie -- Périodiques; Microbiologie -- Périodiques; Maladies infectieuses -- Périodiques; Communicable diseases; Immunology; Microbiology; Electronic journals; Periodicals; 636.08969
• DOI: 10.1016/j.cimid.2019.02.011
• Languages: English
• ISSNs: 0147-9571

Abstract

Highlights: Characterization of AIV-H9N2, pathogenicity and seroprevalence in poultry flocks were conducted. Interestingly, the PI of the H9N2 broiler strain ranged 1.2–1.9, indicating a high pathogenicity. A firstly recorded clinical signs, lesions and IHC revealed a systemic infection of H9N2. A higher seroprevalence was shown in backyard chicken flocks (57.7%) than duck flocks (12.2%). As a first report, a tested high pathogenicity H9N2 virus requires a continuous monitoring. Abstract: This study was conducted to perform the comparative molecular characterization of avian influenza virus (AIV) H9N2, pathogenicity and seroprevalence in commercial and backyard poultry flocks. Fifty commercial poultry flocks were investigated between 2012 and 2015. Eighteen flocks (36%) out of 50 were positive HA. Seven (38.9%) out of 18 were positive by chromatographic strip test for AI common antigen. By Real-time RT-PCR, only two flocks were positive H9. The molecular characterization of two different AI-H9N2 viruses, one isolated from a broiler flock (A/chicken/Egypt/Mansoura-18/2013) and the other from a layer flock (A/chicken/Egypt/Mansoura-36/2015) was conducted on HA gene. Moreover, a higher seroprevalence, using the broiler strain as a known antigen, was shown in backyard chicken flocks 15/26 (57.7%) than duck flocks 9/74 (12.2%). Interestingly, the pathogenicity index (PI) of the H9N2 broiler strain in inoculated experimental chickens ranged from 1.2 (oculonasal route) to 1.9 (Intravenous route). The PI indicated a highly pathogenic effect, with high mortality (up to 100%) in the inoculated chickens correlated with the high mortality (80%) in the flock where the virus was isolated. The firstly recorded clinical signs, including cyanosis in the combs and wattles and subcutaneous haemorrhages in the leg shanks and lesions, as well as histopathology and immunohistochemistry, revealed a systemic infection of the high pathogenicity with the H9N2 virus. Conversely, the H9N2 layer strain showed a low pathogenicity. In conclusion, as a first report, the molecular analysis and pathogenicity of the tested strains confirmed the presence of a high pathogenicity AIV-H9N2 with systemic infections.