H9N2 Influenza Viruses from Israeli Poultry: A Five-Year Outbreak

Abstract

Since 2000, hundreds of H9N2 viruses have been isolated from all types of domestic birds. Although H9N2 is a low-pathogenicity virus, disease has been observed in all types of poultry in the field. Clinical signs ranged from very mild disease to high morbidity and mortality when the virus was associated with a secondary pathogen. Because of the wide range of the virus and the great losses it caused, initially a local vaccination program was implemented, but mass vaccination was quickly authorized. A local strain, isolated in 2002 was selected and is currently in use as an inactivated vaccine. An intensive operation is in progress to characterize the isolates. Several genes (hemagglutinin [HA], neuraminidase, nonstructural protein, nucleoprotein, and matrix) were sequenced, revealing three main groups: the first group included two isolates from 2000, the second group included isolates from 2001 to the beginning of 2003, and the third group included all isolates from 2003 to date. The differences between the second and third groups, in a part of the HA gene, ranged from 3.49% to 6.97% (average 4.57%) of the nucleotides. Similar differences were recorded in the other tested genes. These data could indicate the probable introduction of distinct progenitor viruses into the Israeli poultry population. Furthermore, sequencing of the HA protein of some Israeli isolates revealed the presence of L216 in the binding site; this finding was typical of the H9N2 viruses isolated from humans, which raises the possibility of an influence on host specificity and virulence.

Genetic characterization of avian influenza viruses isolated in Israel during 2000–2006

“…The H9N2 subtype of AIV was spreading in many European, Asian, African, and American countries [1,2,[4][5][6][7][8][9][10][11][12][13][14]. Highly pathogenic H5N1 virus caused major outbreaks among poultry in European, Asian, and African countries [15][16][17][18].…”

“…In reviews of Alexander [1], Senne [2], Brown et al [11], and Banks et al [14] were described general aspects of epidemiology and ecology of the AIV. Molecular and biologic characteristics of H9N2 viruses were presented by Monne et al[4], Jackwood et al [5], Banet-Noach et al [6], Aamir et al [7], Torogi et al [8], Perk et al [9,10], Nili et al [12,13].…”

Isolation of H9N2 avian influenza virus from bobwhite quail (Colinus virginianus) in Egypt

“…Extensive evolutionary genetic analysis has indicated that East Asia has been the major source of H9N2 in the Middle East area [17]. Circulation of H9N2 viruses in the Middle East and Northern Africa since the year 2000 has been frequently reported in Israel, Jordan, Lebanon, Saudi Arabia, the United Arab Emirates, Kuwait, Iraq and Libya, where inactivated vaccines have been implemented in some countries to combat H9N2-associated disease of economical importance in poultry [5,8,17,36]. Nevertheless, isolation of H9N2 virus from poultry has not yet been reported from Egypt, whereas the endemic status of H5N1 virus in poultry in Egypt with frequent, and occasionally fatal, transmissions to the human population since 2006 is well known [3].…”

An H9N2 Influenza Virus Vaccine Prepared from a Non-Pathogenic Isolate from a Migratory Duck Confers Protective Immunity in Mice against Challenge with an H9N2 Virus Isolated from a Girl in Hong Kong

“…H9N2 viruses of each of the three sublineages, G1, Y280, and Korean, were recently isolated from wildbirds and poultry worldwide [3,6,27]. H9N2 viruses were also isolated from pigs and humans in China [4,5,37] and Korea, suggesting that these viruses have the potential to cause pandemic influenza in humans.…”