Prevalence of Two Distinct Genotypes of Highly Pathogenic Avian Influenza A/H5n8 Viruses in Backyard Waterfowls in Upper Egypt During 2018

Abstract

H PAI viruses is a source of major concern for poultry and human health. The hemagglutinin (HA) genes of subtype H5 evolved through reassortment with various neuraminidase subtypes (1-9) to comprise AI H5NX viruses. The co-circulation of group A viruses with low patho-genic avian influenza (LPAI) viruses resulted in emergence of novel reassortants; H5N1 and H5N8 (El-Shesheny et al., 2017). H5N8 viruses has been emerged in Asia since 2010 where the first outbreaks in breeding ducks occurred in China then South Korea, Japan and Taiwan 2014. then quickly spread to other continents as Europe, North America and Africa (Lee et al., 2014).

Epidemiological Disclosing and Molecular Subtyping for the Highly Pathogenic Avian Influenza Viruses H5N8 in Commercial Broilers and Layer Chickens in some Egyptian Governorates

“…No positive H5N1 viruses were reported in the surveyed flocks during our active surveillance which proves a little further circulation of HPAI H5N1 in the poultry population in Egypt during 2023 as in accordance with previous reports of [12,25]. While the prevalence rate of HPAIV H5N8 in our study was 28.3% from vaccinated broilers and layers chickens which is nearby the previously detected results of [13,21,23,26,27]. Whereas Salaheldin et al [28] detected the H5N8 viral infection by QrRT-PCR with higher prevalence rate of 45.1% in vaccinated chicken flocks.…”

“…The HA glycoprotein is the primary determinant of Influenza A viruses virulence with receptor binding properties [30]. The HA cleavage site of the most previously isolated H5N8 strains encodes the motif PLREKRRKR/GLF which is characteristic for pathogenicity of those isolates, our results concluded that and were similar to other recent investigations by many studies [6,13,21,23,31] who concluded that their selected H5N8 isolates have the same motif in HA cleavage site. Furthermore, the genetic analysis of AA identity percent showed that our study isolates have identity percent among each others varied from 99.0 to 99.7% as in previously reported by Setta et al [23] and similar to our results who detected a close proximity to their H5N8 isolates to each others, while found them spaced out in AA identity percent of their isolates with H5 vaccinal strains.…”

“…Based on the phylogenetic analysis to HA gene of our selected H5N8 isolates indicated the presence of those isolates closely related to the clade 2.3.4.4b similar to others isolated from wild birds and domestic poultry in Egypt and worldwide sites as in harmony with the results of [10,11,12,13,23,29] who highlighting the epidemiology and the evolution of HPAIV H5N8 in Egypt within the same clade 2.3.4.4b from 2017 till now.…”

“…HPAIV H5N8 seems to be the predominant influenza A subtype that was detected in the majority of birds species since its first isolation in Egypt in the late 2016 from wild birds [10]. Thereafter, the spread of virus has been reported in different poultry species with devastating economic losses along with many surveillance studies of [2,12,13,20,21] that applied to indicate the prevalence of H5N8 clade 2.3.4.4b in Egypt in the past years.…”

“…In Egypt during the late 2016, the H5N8 virus was firstly recognized and isolated from greenwinged teals and common-coots [10,11]. Thereafter, H Egyptian Journal of Veterinary Sciences https://ejvs.journals.ekb.eg/ a definitely six genotypes of H5N8 with various reassorted combinations were reported in both domestic and migratory birds in Egypt in which the virus spreads vigorously in Egyptian poultry farms causing significant hazard to the poultry sectors [2,12,13].…”