Publikationsdatenbank

Emerging infectious bronchitis virus (IBV) in Egypt:
evidence for an evolutionary advantage of a new S1 variant with a unique gene 3ab constellation (2020)

Art

Zeitschriftenartikel / wissenschaftlicher Beitrag

Autoren

Moharam, Ibrahim

Sultan, Hesham

Hassan, K.

Ibrahim, Mahmoud

Shany, Salama

Shehata, Awad A.

Abo-ElKhair, Mohammed

Pfaff, Florian

Höper, Dirk

El Kady, Magdy

Beer, Martin

Harder, Timm

Hafez, Hafez (WE 15)

Grund, Christian

Quelle

Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases ; MEEGID

Bandzählung: 85

Seiten: Artikel 104433

ISSN: 1567-1348

Sprache

Englisch

Verweise

URL (Volltext): https://www.sciencedirect.com/science/article/abs/pii/S1567134820302641

DOI: 10.1016/j.meegid.2020.104433

Pubmed: 32622080

Kontakt

Nutztierklinik: Abteilung Geflügel

Königsweg 63
14163 Berlin
+49 30 838 62676
gefluegelkrankheiten@vetmed.fu-berlin.de

Abstract / Zusammenfassung

Infectious bronchitis virus (IBV), a gamma-coronavirus, causes infectious bronchitis (IB), a major respiratory disease of chicken. Its high mutation rate in conjunction with recombination of the RNA genome constantly creates IBV variants that are difficult to control by currently available vaccines. In this study, we addressed the question whether small-scale holdings might harbor IBV variants that serve as a reservoir for newly emerging variants. Egyptian IBV isolate EGY/NR725/2016 (NR725/16) from a small-scale broiler farm was assigned to genotype I, clade 23 (S1:GI-23), based on partial S1 gene sequences and corroborated by full genome sequencing. Analysis of the S1 gene established three subclades for historical IBV strains (S1:GI-23.1, S1:GI-23.2.1 and S1:GI-23.2.2) and confirmed NR725/16 as being part of a separate fourth subclade (S1:GI-23.3). Samples from the years 2018 and 2019 revealed that the new subclade prevails in Egypt, carrying fixed mutations within the hypervariable regions (HVR) 1-3 of the S1 protein that affect two neutralization sensitive epitopes at sites 294F, 297S and 306Y (48.2) and 329R (62.1). In addition, recombination was recognized in isolate NR 725/16, with intra-subtype mixing for the entire genes 3ab and E and inter-subtype mixing for the entire gene 6b with a close match to QX like viruses of genotype GI-19. Further analysis of gene 3ab detected the homologous gene pool to NR725/16 in samples from 2013 (3ab:C) and closely related 3ab genotypes in IBV Egyptian isolates from 2016, 2018 and 2019. These data prove a flourishing exchange between poultry holdings with a common gene pool. The continued circulation of viruses harboring genes S1:GI-23.3 and 3ab:C indicates an evolutionary advantage of this combination possibly by combining antigenic escape with modulated pathogenicity to facilitate IBV spread in the vaccinated poultry population in Egypt.