title: Determination of serum neutralization antibodies against seasonal influenza A strain H3N2 and the emerging strains 2009 H1N1 and avian H5N1.
abstract: BACKGROUND
  Humoral virus neutralizing activity is crucial in preventing influenza virus infection. However, the influenza neutralizing activity in the general population remains unclear.
  
  
  METHODS
  In this study we performed a serological survey of 200 blood donors from Guangzhou, China. Using a microneutralization (MN) assay, neutralizing activities against influenza A 2009 H1N1, H3N2 and H5N1 were measured. Anti-haemagglutinin antibody was assayed by haemagglutination inhibition (HI) test. Also, antibodies against M1 and M2 matrix proteins were measured using an enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  By MN assay, 86% of the individuals showed neutralizing activity against H3N2, 11% against 2009 H1N1, and none against H5N1. The positive rate for H3N2 increased as the age of individuals increased. Interestingly, males displayed a 4 times higher positive rate against 2009 H1N1 than females. The results of ELISA revealed that 97.5% of the individuals had positive M1 titres and 21% had positive M2 titres. Furthermore, anti-haemagglutinin antibody had a much higher correlation with the neutralization activity than anti-M1 and anti-M2 antibodies.
  
  
  CONCLUSIONS
  Neutralizing activities against H5N1 and 2009 H1N1 were low in the general population. Therefore, public health agencies should design strategies for preventing potential H5N1 and 2009 H1N1 pandemics.
authors.affiliation: State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China.
authors.forename: Ruiqi
authors.initials: R
authors.lastname: Zhang
authors.forename: Xia
authors.initials: X
authors.lastname: Rong
authors.forename: Weiqi
authors.initials: W
authors.lastname: Pan
authors.forename: Tao
authors.initials: T
authors.lastname: Peng
mesh_terms: D000328:Adult; D057134:Antibodies, Neutralizing / Q000097:blood*; D000914:Antibodies, Viral / Q000097:blood*; D002681:China; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology*; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology* / Q000821:virology*; D008297:Male; D008875:Middle Aged; D009500:Neutralization Tests; D016036:Seroepidemiologic Studies
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral