Genetic characterization of influenza A virus subtype H7N1 isolated from quail, Thailand

Abstract

In Thailand, surveillance for the highly pathogenic avian influenza virus H5N1 (HPAI-H5N1) has revealed high prevalence of the virus in quail in live-bird markets. This study monitored avian influenza viruses (AIVs) in quail farms in an area at high risk for HPAI-H5N1 over a 12-month period from 2009 to 2010. One-step real-time RT-PCR (rRT-PCR) results showed that 1.18 % of swab samples (24/2,040) were AIV positive. Among the rRT-PCR positive samples, three samples were identified as subtype H7N1. One Thai H7N1 virus designated "A/quail/Thailand/CU-J2882/2009 (H7N1)" was subjected to whole genome sequencing and genetic characterization. Phylogenetic analysis showed that the HA gene of the Thai H7N1 virus groups with those of the H7 Eurasian viruses. Interestingly, the NA gene of the virus was found to be closely related to those of the HPAI-H5N1 viruses from Vietnam and Thailand. This study constitutes the first report on AIV H7N1 in Thailand. Our results suggest the possibility of genetic reassortment between AIV-H7NX and HPAI-H5N1 in quail. The HA cleavage site of the Thai H7N1 virus contains no multiple amino acid insertions, suggesting low pathogenic characteristics for this virus.

Evidence of Influenza A Virus Infection in Cynomolgus Macaques, Thailand

“…Secondly, there was a lack of local avian influenza virus strains used in the serological tests. At present, various LPAI subtypes, including H1, H3, H4, H7, H8, H10, and H11, have been identified in domestic avian species [ 23 , 24 , 28 , 29 , 30 , 31 ] and the LPAI subtype of H12 has been successfully isolated from a watercock and lesser whistling duck in Thailand [ 32 ]. Based on our virus resources, we used 16 influenza HA subtypes (H1–H16) of the AIV and two Thailand strains of the human H1N1 influenza virus as the tested antigen.…”

Genetic and antigenic characterization of the first H7N7 low pathogenic avian influenza viruses isolated in Vietnam

“…While no outbreaks of H7 HPAIV infection have been reported in Southeast Asian countries, the detection of H7 LPAIVs has been reported in domestic poultry and wild birds, e.g., in Singapore [H7N1 in 1994-1995(Banks et al, 2000]; Thailand [H7N1 in 2009, H7N6 in 2010, and H7N4 in 2010-2011(FAO, 2019Wongphatcharachai et al, 2014)]; Cambodia [H7N3, H7N4, H7N7, and H7N9 2017(FAO, 2019Suttie et al, 2018)]; and Vietnam [H7N1 in 2012 (Okamatsu et al, 2013)]. Because of the potential for H5/H7 LPAIVs to evolve into HPAIVs through the insertion of polybasic amino acids into the HA cleavage site during the circulation of these viruses in poultry (Silvano et al, 1997) and the emergence of antigenic variants under the pressure of vaccine, which might lead to the failure of vaccination campaign (Eladl et al, 2011;Ibrahim et al, 2013;Bai et al, 2019;Jia et al, 2019), the circulation of H5/H7 LPAIVs in the poultry population should be minimized to enhance disease control efforts.…”