Epidemiological survey and genetic evolution of H9 subtype influenza viruses in Shanghai, China, from 2006 to 2010

Abstract

The H9N2 influenza virus is endemic in poultry. We report its occurrence in live-poultry markets, fair-trade markets and poultry farms in the Shanghai region between September 2006 and December 2010. An analysis of partial sequences of the HA, NA, PB1, PB2 and NP genes of eleven distinct H9N2 isolates revealed that all carried an RSSR motif at the cleavage site of HA, diagnostic of low pathogenicity in chickens. A phylogenetic analysis indicated that these isolates are derived from the lineage represented by Duck/HK/Y280/97, but they have evolved a range of reassortments. Their PB1 and NP sequences resembled those of H5N1 strains, indicating a hybrid origin involving both H9 and H5 strains. The HA and NA sequences present in all eleven isolates resembled those of the Duck/HK/Y280/97-like lineage. Infection by H9N2 is commonplace in Shanghai live-poultry markets, allowing the viruses to have evolved rapidly.

Alternative Reassortment Events Leading to Transmissible H9N1 Influenza Viruses in the Ferret Model

“…Finally, the HA S319C mutation lies in the p2 position of the HA cleavage site. The RSSR/G motif is fairly conserved in Eurasian avian H9 isolates, but the p2 and p3 sites are far more flexible in swine isolates (33)(34)(35). We detected this mutation in only 20% of reads from the RCP5 sample.…”

Genetic analysis of polymerase complex (PA, PB1 and PB2) genes of H9N2 avian influenza viruses from Iran (1999 to 2009)

“…This finding suggests a high degree of diversity among the H9N2 viruses in the regions of the Middle East and Indian sub-continent. In recent years, novel genotypes of H9N2 avian influenza viruses from domestic poultry in China, Korea, Vietnam, India and Pakistan have been identified and well characterized [27][28][29][30][31][32][33][34] . In February 2006, highly pathogenic H5N1 virus was isolated from wild birds in Northern provinces of Iran [28] .…”

A small-scale study on airborne transmission of H9N2 avian influenza virus under field conditions

“…Although H9N2 AIV belongs to the low pathogenic avian influenza (LPAI) virus, it increases morbidity and mortality rates when poultry are co-infected with other pathogens, such as Escherichia coli and Staphylococcus aureus [4,5]. In China, since H9N2 AIV was first isolated from diseased chickens in Guangdong Province in 1994, the virus has become the most prevalent type nationwide [6][7][8][9][10][11].…”