title: Antibody correlates and predictors of immunity to naturally occurring influenza in humans and the importance of antibody to the neuraminidase.
abstract: BACKGROUND
  Serum antibody to the hemagglutinin (HA) of influenza viruses is a correlate and predictor of immunity to influenza in humans; the relative values of other correlates are uncertain.
  
  
  METHODS
  Serum and nasal secretions (NS) were collected in fall and spring of 2009-2011 from healthy adults who were monitored for acute respiratory illness (ARI). Serum samples were tested for hemagglutination-inhibition (HAI) antibody increase and secretions for virus if ill; enrollment sera were also tested for neuraminidase-inhibiting (NI) antibody and NS for neutralizing (neut), NI, immunoglobulin A (IgA), and immunoglobulin G (IgG) anti-HA antibody.
  
  
  RESULTS
  Serum anti-HA and anti-neuraminidase (NA) antibody titers to 2009(H1N1) pandemic influenza virus (pH1N1) correlated with titers in NS (including IgA and IgG antibody). Increasing anti-HA and anti-NA titers in serum and NS tests all correlated with reducing infection and infection-associated illness. Multivariate analyses indicated serum HAI and NI each independently predicted immunity to infection and infection-associated illness. Only serum NI independently predicted reduced illness among infected subjects.
  
  
  CONCLUSIONS
  Increasing anti-HA and NA antibody in serum and secretions correlated with reducing pH1N1 influenza virus infection and illness in healthy young adults. Both anti-HA and anti-NA antibody are independent predictors of immunity to influenza; ensuring induction of both by vaccination is desirable.
authors: Departments of Molecular Virology and Microbiology and Medicine, Baylor College of Medicine, One Baylor Plaza, MS BCM280, Houston, TX 77030, USA. rcouch@bcm.edu
authors: Robert B
authors: RB
authors: Couch
authors: Robert L
authors: RL
authors: Atmar
authors: Luis M
authors: LM
authors: Franco
authors: John M
authors: JM
authors: Quarles
authors: Janet
authors: J
authors: Wells
authors: Nancy
authors: N
authors: Arden
authors: Diane
authors: D
authors: Niño
authors: John W
authors: JW
authors: Belmont
mesh_terms: D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood*; D016009:Chi-Square Distribution; D005260:Female; D006385:Hemagglutination Inhibition Tests; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000276:immunology*; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology* / Q000821:virology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D017817:Nasal Lavage Fluid / Q000737:chemistry / Q000276:immunology* / Q000821:virology; D009439:Neuraminidase / Q000276:immunology*; D011237:Predictive Value of Tests; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D009439:Neuraminidase