title: The pandemic (H1N1) 2009 influenza virus is resistant to mannose-binding lectin.
abstract: BACKGROUND
  Mannose-binding lectin (MBL) is an important component of innate immunity because it promotes bacterial clearance and neutralization of human influenza A viruses. Since a majority of humans have no neutralizing antibody against the pandemic (H1N1) 2009 influenza (pandemic 2009) virus, innate immunity may be crucial and MBL susceptibility may therefore influence viral pathogenesis.
  
  
  RESULTS
  We examined MBL susceptibility of influenza A viruses and observed that the pandemic 2009 virus was resistant to MBL, whereas all seasonal influenza A viruses tested were susceptible. The mortality of mice infected with a seasonal H1N1 influenza virus was evidently enhanced on transient blockage of MBL activity by simultaneous inoculation of mannan, whereas mannan inoculation had no effect on mice infected with a pandemic 2009 virus. This indicates that MBL protects mice against infection with the seasonal virus but not against that with the pandemic 2009 virus.
  
  
  CONCLUSIONS
  These results indicate that the pandemic 2009 virus is not susceptible to MBL, an important component of innate immunity.
authors.affiliation: Department of Microbiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama 701-0192, Japan.
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Tokunaga
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ushirogawa
authors.forename: Masanobu
authors.initials: M
authors.lastname: Ohuchi
mesh_terms: D000818:Animals; D003165:Complement System Proteins / Q000276:immunology*; D004195:Disease Models, Animal; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D037601:Mannose-Binding Lectin / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009976:Orthomyxoviridae Infections / Q000276:immunology / Q000401:mortality; D012376:Rodent Diseases / Q000276:immunology / Q000401:mortality; D016019:Survival Analysis
chemical_list: D037601:Mannose-Binding Lectin; D003165:Complement System Proteins