title: Introduction and enzootic of A/H5N1 in Egypt: Virus evolution, pathogenicity and vaccine efficacy ten years on.
abstract: It is almost a decade since the highly pathogenic H5N1 avian influenza virus (A/H5N1) of clade 2.2.1 was introduced to Egypt in 2005, most likely, via wild birds; marking the longest endemic status of influenza viruses in poultry outside Asia. The endemic A/H5N1 in Egypt still compromises the poultry industry, poses serious hazards to public health and threatens to become potentially pandemic. The control strategies adopted for A/H5N1 in Egyptian poultry using diverse vaccines in commercialized poultry neither eliminated the virus nor did they decrease its evolutionary rate. Several virus clades have evolved, a few of them disappeared and others prevailed. Disparate evolutionary traits in both birds and humans were manifested by accumulation of clade-specific mutations across viral genomes driven by a variety of selection pressures. Viruses in vaccinated poultry populations displayed higher mutation rates at the immunogenic epitopes, promoting viral escape and reducing vaccine efficiency. On the other hand, viruses isolated from humans displayed changes in the receptor binding domain, which increased the viral affinity to bind to human-type glycan receptors. Moreover, viral pathogenicity exhibited several patterns in different hosts. This review aims to provide an overview of the viral evolution, pathogenicity and vaccine efficacy of A/H5N1 in Egypt during the last ten years.
authors.affiliation: Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, D-17493 Greifswald-Insel Riems, Germany; National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Dokki, Giza 12618, Egypt.
authors.forename: E M
authors.initials: EM
authors.lastname: Abdelwhab
authors.affiliation: National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Dokki, Giza 12618, Egypt.
authors.forename: M K
authors.initials: MK
authors.lastname: Hassan
authors.affiliation: Virology Department, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef 62511, Egypt; Microbiology Department, Virology Division, College of Medicine, Taif University, Al-Taif 21944, Saudi Arabia.
authors.forename: A S
authors.initials: AS
authors.lastname: Abdel-Moneim
authors.affiliation: Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, D-17493 Greifswald-Insel Riems, Germany; National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Dokki, Giza 12618, Egypt.
authors.forename: M M
authors.initials: MM
authors.lastname: Naguib
authors.affiliation: Center of Scientific Excellence for Influenza Viruses, National Research Centre (NRC), Dokki, Giza 12311, Egypt; Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, Giessen 35392, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Mostafa
authors.affiliation: Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
authors.forename: I T M
authors.initials: ITM
authors.lastname: Hussein
authors.affiliation: National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Dokki, Giza 12618, Egypt.
authors.forename: A
authors.initials: A
authors.lastname: Arafa
authors.affiliation: National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Dokki, Giza 12618, Egypt.
authors.forename: A M
authors.initials: AM
authors.lastname: Erfan
authors.affiliation: National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Dokki, Giza 12618, Egypt.
authors.forename: W H
authors.initials: WH
authors.lastname: Kilany
authors.affiliation: National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Dokki, Giza 12618, Egypt; Animal Health Research Institute, Dokki, 12618 Giza, Egypt.
authors.forename: M G
authors.initials: MG
authors.lastname: Agour
authors.affiliation: National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Dokki, Giza 12618, Egypt.
authors.forename: Z
authors.initials: Z
authors.lastname: El-Kanawati
authors.affiliation: Department of Virology, Faculty of Veterinary Medicine, Cairo University, Giza 12211, Egypt.
authors.forename: H A
authors.initials: HA
authors.lastname: Hussein
authors.affiliation: National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Dokki, Giza 12618, Egypt.
authors.forename: A A
authors.initials: AA
authors.lastname: Selim
authors.affiliation: National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Dokki, Giza 12618, Egypt.
authors.forename: S
authors.initials: S
authors.lastname: Kholousy
authors.affiliation: Veterinary Serum and Vaccine Research Institute, Abbasia, El-Sekka El-Beida St., PO Box 131, Cairo 11381, Egypt.
authors.forename: H
authors.initials: H
authors.lastname: El-Naggar
authors.affiliation: National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Dokki, Giza 12618, Egypt.
authors.forename: E F
authors.initials: EF
authors.lastname: El-Zoghby
authors.affiliation: National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Dokki, Giza 12618, Egypt.
authors.forename: A
authors.initials: A
authors.lastname: Samy
authors.affiliation: Avian Influenza Group, The Pirbright Institute, Ash Road, Pirbright, Woking GU24 0NF, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Iqbal
authors.affiliation: Department of Avian and Rabbit Medicine, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt.
authors.forename: A
authors.initials: A
authors.lastname: Eid
authors.affiliation: Animal Health Research Institute, Dokki, 12618 Giza, Egypt.
authors.forename: E M
authors.initials: EM
authors.lastname: Ibraheem
authors.affiliation: Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, Giessen 35392, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Pleschka
authors.affiliation: Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, D-17493 Greifswald-Insel Riems, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Veits
authors.affiliation: National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Dokki, Giza 12618, Egypt.
authors.forename: S A
authors.initials: SA
authors.lastname: Nasef
authors.affiliation: Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, D-17493 Greifswald-Insel Riems, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Beer
authors.affiliation: Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, D-17493 Greifswald-Insel Riems, Germany.
authors.forename: T C
authors.initials: TC
authors.lastname: Mettenleiter
authors.affiliation: Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, D-17493 Greifswald-Insel Riems, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Grund
authors.affiliation: National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Dokki, Giza 12618, Egypt; Animal Health Research Institute, Dokki, 12618 Giza, Egypt.
authors.forename: M M
authors.initials: MM
authors.lastname: Ali
authors.affiliation: Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, D-17493 Greifswald-Insel Riems, Germany.
authors.forename: T C
authors.initials: TC
authors.lastname: Harder
authors.affiliation: Institute of Poultry Diseases, Freie Universität Berlin, Königsweg 63, 14163 Berlin, Germany. Electronic address: Hafez@vetmed.fu-berlin.de.
authors.forename: H M
authors.initials: HM
authors.lastname: Hafez
mesh_terms: D000818:Animals; D004534:Egypt / Q000453:epidemiology; D019143:Evolution, Molecular; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D005585:Influenza in Birds / Q000453:epidemiology*; D007251:Influenza, Human / Q000453:epidemiology*; D059645:Mutation Rate; D011200:Poultry / Q000821:virology; D011201:Poultry Diseases / Q000453:epidemiology / Q000821:virology*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics
chemical_list: D037521:Virulence Factors
keywords: Clade 2.2.1; Egypt; Genetic evolution; H5N1; Highly pathogenic avian influenza virus; Pandemic threat