Molecular epidemiological surveys of H5 subtype highly pathogenic avian influenza viruses in poultry in China during 2007-2009

Increased substitution rate in H5N1 avian influenza viruses during mass vaccination of poultry

“…Because substitutions in the HA1 subunit play a much more important role than those in the HA2 subunit in vaccine escape, the results support the idea that mass vaccination, as an evolutionary selective force, facilitates the emergence of vaccine-resistant viruses. This is also consistent with previous reports that many amino acid substitutions in the HA1 subunit of H5N1 HPAI viruses occurred at antigenic sites [3,25,40]. In addition, it has also been found by others that the substitution rate of viruses may be elevated by selection of immune escape [41,42].…”

“…Circulation of H5N1 HPAI virus in China was firstly identified in 1996, and was confirmed in each of the subsequent years [1][2][3]9,10]. Gene sequences of some H5N1 HPAI viruses circulating in China in 1996-2010 have been available in GenBank, or reported herein.…”

“…We have reported the HA gene sequences of 55 H5N1 HPAI viruses isolated in 2007-2009 with GenBank accession numbers HM006764-HM006818 and HM583607-HM583609 [3]. Here, we report sequences of 17 additional H5N1 HPAI viruses isolated in 2010 (the relevant infection information has been released online by Ministry of Agriculture of China, http://www.moa.gov.cn/zwllm/tzgg/gb/sygb/).…”

“…Chin Sci Bull, 2012, 57: 24192424, doi: 10.1007/s11434-012-5215-y H5N1 subtype highly pathogenic avian influenza (HPAI) viruses have been circulating widely in wild birds and domestic fowls for years in Eurasia and Africa, despite great efforts to control the disease [1][2][3][4]. Consequently, the virus has caused huge economic loss in poultry in many affected countries.…”

“…Similar exotic sequences were excluded as representatives for HA2, and thus they were not covered in Figure S2. The selected representatives covered all known major clades circulating during the relevant periods in the three countries [1][2][3]9,10,13,31]. It should be noted that full-length sequences of some H5N1 HPAI viruses were not available for both HA1 and HA2 in GenBank, and the HA1 and HA2 representative sequences were selected at random, respectively.…”