Genetic and antigenic evolution of H9N2 avian influenza viruses circulating in Egypt between 2011 and 2013

Abstract

Avian influenza virus subtype H9N2 has been circulating in the Middle East since the 1990s. For uncertain reasons, H9N2 was not detected in Egyptian farms until the end of 2010. Circulation of H9N2 viruses in Egyptian poultry in the presence of the enzootic highly pathogenic H5N1 subtype adds a huge risk factor to the Egyptian poultry industry. In this study, 22 H9N2 viruses collected from 2011 to 2013 in Egypt were isolated and sequenced. The genomic signatures and protein sequences of these isolates were analyzed. Multiple mammalian-host-associated mutations were detected that favor transmission from avian to mammalian hosts. Other mutations related to virulence were also identified. Phylogenetic data showed that Egyptian H9N2 viruses were closely related to viruses isolated from neighboring Middle Eastern countries, and their HA gene resembled those of viruses of the G1-like lineage. No reassortment was detected with H5N1 subtypes. Serological analysis of H9N2 virus revealed antigenic conservation among Egyptian isolates. Accordingly, continuous surveillance that results in genetic and antigenic characterization of H9N2 in Egypt is warranted.

Epidemiology, ecology and gene pool of influenza A virus in Egypt: Will Egypt be the epicentre of the next influenza pandemic?

“…16,36,66 Although predictable, the reassortment between H5N1 and H9N2 has not been yet reported. 70 The highest incidence of H9N2 infections was in January 2012 (6.6%, 49/ 736) and concentrated mainly in the Nile Delta. 16 The routes of the introduction of H9N2 into Egypt are not yet clear.…”

“…16 In 2011-2013, one study identified H9N2 in 24 out 60 broiler, one out of 5 layer and one out of 5 breeder flocks 69 and the second study isolated the virus from 22 broiler flocks. 70 While the majority of infected chickens showed respiratory distress 66,68 and there was a decrease in egg production in breeder and layer flocks, 68 infected quails and some broiler flocks were clinically healthy. 16,67,70 Importantly, co-infection or prior infection with H5N1 and H9N2 was also reported in many cases in poultry in Egypt.…”

“…70 While the majority of infected chickens showed respiratory distress 66,68 and there was a decrease in egg production in breeder and layer flocks, 68 infected quails and some broiler flocks were clinically healthy. 16,67,70 Importantly, co-infection or prior infection with H5N1 and H9N2 was also reported in many cases in poultry in Egypt. 16,36,66 Although predictable, the reassortment between H5N1 and H9N2 has not been yet reported.…”

“…65,70 Long-term circulation of both pandemic-potential viruses with progressive adjustment to optimize their evolution toward efficient transmission in human is very critical in Egypt. Therefore, Egypt has been considered a far greater risk than H5N1 viruses circulating in other countries for the emergence of pandemic.…”

Active surveillance of avian influenza viruses in Egyptian poultry, 2015

“…Weakly pathogenic avian influenza H9N2 viruses have been isolated from chickens, turkeys and quails in Egypt (11)(12)(13). All the H9N2 isolates obtained between 2010 and 2013 were closely related to Middle Eastern H9N2 viruses (12,13).…”