Mutation signature in neuraminidase gene of avian influenza H9N2/G1 in Egypt

Abstract

The low pathogenic avian influenza (LPAI) H9N2 subtype has become the most prevalent and widespread in many Asian and Middle Eastern countries. It causes an enzootic situation in commercial poultry and known as a potential facilitator virus that can be transmitted to human from birds. The neuraminidase (NA) gene plays an important role the release and spread of the virus from infected cells and throughout the bird. The complete nucleotide sequences of the NA gene of seven H9N2 viruses collected from apparent healthy chicken and quail flocks in Egypt during 2014-2015, were amplified and sequenced. The phylogenetic relationships were investigated and all viruses were belonging to the A/Q/HK/G1/97 strain (G1-like). There were no insertions or deletions or shortening in NA stalk regions when compared to Y280-lineage and the human H9N2 isolates. No obvious changes NA interactions with antiviral drugs. We found that the Egyptian H9N2 viruses have seven glycosylation sites like the most recorded H9N2 viruses in the country, except A/Q/Egypt/14864V/2014 virus which has only six. The NA has four amino acid substitutions distributed in different parts of the hemadsorbing site. The most characteristic substitutions in this site were S372A and W403R these substitutions were a distinctive feature resembling to human H9N2, H2N2 and H3N2 viruses but differs from the other avian influenza viruses. These Special features of surface glycoproteins of LPAI-H9N2 viruses refer to the tendency for enhanced introductions into humans and ensuring the importance of poultry in the transfer influenza viruses.

Novel reassortant of H9N2 avian influenza viruses isolated from chickens and quails in Egypt

“…This study demonstrated much genetic variability in the NA gene in the quail isolate, detecting variability in two glycosylation sites in positions 69 and 306. This result was in line with the study of Mosaad et al [18], who detected six glycosylation sites in the NA gene of the H9N2 subtypes isolated from Egypt (A/Q/ Egypt/14864V/2014). The substitution mutations in the NA protein may affect the virus's pathogenicity to poultry and transmissibility to humans.…”

“…Moreover, a novel Available at www.veterinaryworld.org/Vol.14/August-2021/21.pdf reassortant H9N2 virus emerged among pigeons in 2014 [17]. Furthermore, genetic changes in the neuraminidase (NA) gene of avian influenza H9N2 isolated from chicken and quails in Egypt have been reported [18]. Simultaneously, progressive evolution of the H9N2 subtype in the Middle East region has been indicated [18,19].…”

“…Furthermore, genetic changes in the neuraminidase (NA) gene of avian influenza H9N2 isolated from chicken and quails in Egypt have been reported [18]. Simultaneously, progressive evolution of the H9N2 subtype in the Middle East region has been indicated [18,19].…”

Respiratory disease due to mixed viral infections in poultry flocks in Egypt between 2017 and 2018: Upsurge of highly pathogenic avian influenza virus subtype H5N8 since 2018

“…Moreover, several coding mutations were delineated in the NA haemadsorption sites: R372A, I402N and R403W (Table 5). Substitutions in these sites had been associated with adaptation to mammalian hosts (Matrosovich, Krauss, & Webster, 2001; Mosaad, Arafa, Hussein, & Shalaby, 2017) . The NA of the four H9N2 viruses under study has eight potential N‐linked glycosylation sites similar to ancestral H9 G1 strains (44, 61, 69, 86, 146, 200, 234, 402, 472).…”

“…It may be speculated that under field conditions, antigenically distinct clade 2.3.4.4b viruses are not sufficiently controlled by such vaccine-induced immunity. This scenario would call for a bivalent TA B L E 5 Characteristic amino acid substitutions in haemadsorption (HB) and N-glycosylation (NGS) sites of H9N2 neuraminidase N2 sequences obtained in this study versus older strains in Egypt Patterns of Egyptian H9N2 strains according toMosaad et al (2017). HB and NGS of H9N2 NA protein according toButt, Siddique, Idrees, and Tong (2010).…”