title: [Analysis of characteristics of whole-genome of influenza A H1N1 virus in Qingdao between year 2009 and 2011].
abstract: OBJECTIVE
  To investigate characteristics of the whole-genome of influenza A H1N1 virus circulated in Qingdao from year 2009 to 2011.
  
  
  METHODS
  RNA of 35 influenza A H1N1 virus isolates circulated in Qingdao between year 2009 and 2011 was extracted and all segments were amplified by RT-PCR. The sequence was then detected and assembled by software Sequencher.25 HA full-length sequences published on GenBank were selected as reference. While MEGA 5.0 software package was explored for phylogenetic analysis to characterize the molecular feature with reference to the whole-genome sequence and the hemagglutinin (HA).1068 HA sequences of influenza A H1N1 virus isolated worldwide from August 2010 to March 2011 were downloaded for amino acid mutation analysis.
  
  
  RESULTS
  On the HA genes phylogenetic tree, the virus were separately divided into 4 clades in 2009-2010 and 2010-2011 surveillance season, each with a preponderant epidemic clade. The homogeneity of nucleotide and amino acids of HA isolates were 99.6%-99.9% and 99.1%-99.8% respectively in 2009-2010 surveillance season; 99.1%-99.6% and 98.2%-99.1% respectively in 2010-2011 surveillance season. The homogeneity of nucleotide and amino acids of the preponderant isolates were separately 98.8%-99.8% and 98.0%-99.6%. Compared with the vaccine strain, there were separately 14 and 12 variant amino acids of virus HA in the two surveillance season, involving 10 antigen sites and 5 positive selected sites. The sequence analysis of neuraminidase protein showed that the positions 247, 274 presented serine and histidine(S247, H274) respectively. The sequence analysis of M2 protein showed that the isolated A H1N1 viruses presented asparagine in amino acid site 31 (N31).
  
  
  CONCLUSIONS
  All the A H1N1 influenza virus circulated in Qingdao from year 2009 to 2011 presented continual variation and therefore caused antigenic drift. All the isolations were adamantane-resistance, but susceptible to inhibitors of neuraminidase.
authors: Department of Microorganism and Parasite Test, Qingdao Municipal Center for Disease Prevention and Control, Qingdao 266033, China. Email: wzg-003@163.com.
authors: Zhao-guo
authors: ZG
authors: Wang
authors: Department of Microorganism and Parasite Test, Qingdao Municipal Center for Disease Prevention and Control, Qingdao 266033, China.
authors: Ting-ting
authors: TT
authors: Yang
authors: Department of Microorganism and Parasite Test, Qingdao Municipal Center for Disease Prevention and Control, Qingdao 266033, China.
authors: Qing
authors: Q
authors: Chai
authors: Department of Microorganism and Parasite Test, Qingdao Municipal Center for Disease Prevention and Control, Qingdao 266033, China.
authors: Ping
authors: P
authors: Yu
authors: Department of Microorganism and Parasite Test, Qingdao Municipal Center for Disease Prevention and Control, Qingdao 266033, China.
authors: Xiao-lin
authors: XL
authors: Liu
authors: Department of Microorganism and Parasite Test, Qingdao Municipal Center for Disease Prevention and Control, Qingdao 266033, China.
authors: Hai-ping
authors: HP
authors: Duan
authors: Department of Microorganism and Parasite Test, Qingdao Municipal Center for Disease Prevention and Control, Qingdao 266033, China.
authors: Ying
authors: Y
authors: Yi
mesh_terms: D000595:Amino Acid Sequence; D002681:China / Q000453:epidemiology; D016679:Genome, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology / Q000821:virology*; D009439:Neuraminidase / Q000235:genetics; D010802:Phylogeny; D012367:RNA, Viral; D020539:Sequence Analysis, Protein
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D012367:RNA, Viral; D009439:Neuraminidase