Avian influenza viruses, H9N2 subtype, are endemic in Asia and the Middle East. Israeli H9N2 (G1 lineage) consist of five phylogenetic clades since the year 2000: Clades I, II and III originated in the Far East and co-populated Israel, Jordan and Lebanon, clade IV resembled Egyptian, Jordan and Lebanon AIV H9N2 strains, while Israeli clade V originate in Saudi Arabia and Persian Gulf.
The dynamic phylogenetic evaluation of H9N2 HA included AIVs isolated between 2000-2012 provided novel information: (1) The time to most recent common ancestor (tMRCA) indicated that first H9N2 detection occurredwith its introduction. (2) The Skyline dynamics of genetic diversity revealed two peaks, corresponding to clades III and IV and the two vaccines, (3) The mean evolution rate, 6.123 E-3 substitutions/site/year, similar to countries that use AIV vaccination.
The influence of the inter-clade genetic differences on vaccination efficacy was evaluated in experimental vaccination/challenge trials in SPF chicks. Vaccines prepared with Montanide adjuvant (Seppic, Inc. France) included strains from clades I+II and V. When challenged with old and new AIV strains, cross-clade protections was observed.
Acknowledgment
We thank all coleagues for AIV diagnosis and sequencing at KVI. The study was supported by BARD grant US-4379-11.
