title: Defective interfering virus protects elderly mice from influenza.
abstract: BACKGROUND
  We have identified and characterised a defective-interfering (DI) influenza A virus particles containing a highly deleted segment 1 RNA that has broad-spectrum antiviral activity. In young adult mice it exerts protection against several different subtypes of influenza A virus (defined here as homologous or genetically compatible protection) and against a paramyxovirus and an influenza B virus (heterologous or genetically unrelated protection). Homologous protection is mediated by replication competition between the deleted and full-length genomes, and heterologous protection occurs through stimulation of innate immunity, especially interferon type I.
  
  
  METHODS
  A single dose of the protective DI virus was administered intranasally to elderly mice at -7, -1 and +1 days relative to intranasal challenge with influenza A virus.
  
  
  RESULTS
  A single dose of the DI virus given 1 or 7 days protected elderly mice, reducing a severe, sometimes fatal disease to a subclinical or mild infection. In contrast, all members of control groups treated with inactivated DI virus before challenge became extremely ill and most died. Despite the subclinical/mild nature of their infection, protected mice developed solid immunity to a second infectious challenge.
  
  
  CONCLUSIONS
  The defective interfering virus is effective in preventing severe influenza A in elderly mice and may offer a new approach to protection of the human population.
authors.affiliation: School of Life Sciences, University of Warwick, Coventry, UK.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Scott
authors.forename: Bo
authors.initials: B
authors.lastname: Meng
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Marriott
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Easton
authors.forename: Nigel J
authors.initials: NJ
authors.lastname: Dimmock
mesh_terms: D000818:Animals; D001835:Body Weight; D003673:Defective Viruses; D004195:Disease Models, Animal; D005260:Female; D007113:Immunity, Innate; D009980:Influenza A virus / Q000276:immunology / Q000472:pathogenicity*; D009981:Influenza B virus / Q000276:immunology / Q000472:pathogenicity*; D007372:Interferons / Q000276:immunology; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D009976:Orthomyxoviridae Infections / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control* / Q000821:virology; D012376:Rodent Diseases / Q000276:immunology / Q000473:pathology / Q000517:prevention & control / Q000821:virology; D012720:Severity of Illness Index; D014779:Virus Replication
chemical_list: D007372:Interferons