Molecular Survey of Respiratory and Immunosuppressive Pathogens Associated with Low Pathogenic Avian Influenza H9N2 Subtype and Virulent Newcastle Disease Viruses in Commercial Chicken Flocks

Abstract

The study was carried out in 48 poultry flocks to elucidate the roles of various complicating pathogens involved along with Newcastle disease (ND)/ low pathogenic avian influenza (LPAI) outbreaks. Necropsy was conducted and samples were collected for the isolation of Newcastle disease virus (NDV), Influenza A virus, infectious bronchitis virus (IBV), pathogenic bacteria; molecular detection of infectious laryngotracheitis virus (ILTV), fowl adeno virus (FAV), chicken anaemia virus (CAV), Mycoplasma synoviae (MS) and Mycoplasma gallisepticum (MG). The isolation results confirmed that 18/48 flocks (37%) were positive for the presence of hemagglutinating agents. Out of 18 hemagglutination (HA) positive flocks, 11 flocks (61%) were positive for both avian influenza virus (AIV) and NDV; 4 flocks (22%) were positive for NDV; and 3 flocks (17%) were positive for AIV. Sequence analysis of hemagglutinin and neuraminidase genes of AIV revealed that all were belonging to LPAI-H9N2 subtype. Sequence analysis of F gene of NDV revealed that they belong to virulent type. The PCR results confirmed the presence of three to seven etiological agents (CAV, FAV, ILTV, MG, MS and avian pathogenic E. coli along with LPAI/NDV from all the 18 HA-positive flocks. The detection rate of triple, quadruple, quintuple, sextuple and sevenfold infections was 17% (3 flocks), 28% (5 flocks), 11%, (2 flocks) 28% (5 flocks) and 17% (3 flocks), respectively. In conclusion, the disease complex involved more than one pathogen, primarily resulting from the interplay between LPAI-H9N2 and NDV; subsequently this could be exacerbated by co-infection with other agents which may cause exacerbated outbreaks that may otherwise go undetected in field.

Molecular evaluation and genetic characterisation of Newcastle disease virus's haemagglutinin‐neuraminidase protein isolated from broiler chickens in Iran

“…Viral replication, transcription, translation and protein processing occur in the host cell's cytoplasm, while virus particles are assembled in the plasma membrane by budding (Bi et al., 2019 ). The three main pathotypes, including velogenic, mesogenic and lentogenic, of NDV are calculated based on the inclusion of the intracerebral pathogenicity index, the intervein pathogenic pathogenicity index, the mean death time and the cleavages of the F proteins (Gowthaman et al., 2016 ; Mayahi & Esmaelizad, 2017 ; Suarez et al., 2020 ). The two proteins, haemagglutinin‐neuraminidase (NA; HN) and F, are the main virulence factor of the virus (B. Liu et al., 2015 ; Ren et al., 2019 ).…”

Metagenomic characterization reveals virus coinfections associated with Newcastle disease virus among poultry in Kenya

“…This is especially evident in backyard poultry systems where the vaccine usually fails because of coinfections with other viruses such as infectious bronchitis virus (IBV) and rotaviruses. It has also been previously reported that NDV normally prepares a conducive environment for several respiratory/immunosuppressive pathogens to complicate the outcome of the disease process [11]. Hence, there is a need to control these coinfections if the vaccination efforts against highly pathogenic NDV are to be achieved.…”

Isolation and Identification of H9N2 influenza and Newcastle disease viruses co-infections in chicken

“…This suggests a role of this pathogen in the sustained circulation of NDV in the region. Gowthaman et al [17] reported that 18/48 of tested flocks (37%) were positive for the isolation of hemagglutinating agents, 11 flocks (61%) out of 18 HA positive flocks were positive for AIV and NDV. Taher et al [18] showed that 41 out of 180 broiler farms were positive for either Infectious bronchitis virus (IBV) or vNDV or AI-H5 and AI-H9 as a single infection as follows: 24, 10, 5 and 2 farms, respectively.…”