title: Respiratory infections by HMPV and RSV are clinically indistinguishable but induce different host response in aged individuals.
abstract: BACKGROUND
  Human metapneumovirus and respiratory syncytial virus can cause severe respiratory diseases, especially in infants, young children, and the elderly. So far it remains unclear why infections in the elderly become life threatening despite the presence of neutralizing antibodies in the serum, and to which extent double infections worsen the clinical course.
  
  
  METHODS
  Young and aged BALB/c-mice were infected with RSV or/and HMPV. Appearance of the mice was observed during course of infection. On day 5 p.i. animals were dispatched by cervical dislocation and levels of TNF-α and NF-κB were determined.
  
  
  RESULTS
  The observation of activity, weight and appearance of the different mice showed no differences among the tested groups. Despite this, the immunologic response depends on the animals' age and the virus they were infected with. In young animals, NF-κB levels were elevated if infected with HMPV and HMPV/RSV but remained low in RSV infections, whereas in aged animals the opposite was observed: solely RSV-infected animals showed elevated levels of NF-κB. TNF-α was slightly elevated in HMPV-infected young and old animals, but only in young animals this elevation was significant.
  
  
  CONCLUSIONS
  Contrary to other studies, no weight loss or change in activity despite productive lung infection with the different viruses were observed. This may be due to the weaker anaesthesia or the lesser volume of virus solution used, leading to less stress in the animals. The observed differences in TNF-α and NF-κB elevation lead to the assumption that young and old individuals have different mechanisms to react against the viruses.
authors.affiliation: Institute for Virology, University of Bonn, Bonn, Germany.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Ditt
authors.forename: Jessica
authors.initials: J
authors.lastname: Lüsebrink
authors.forename: Ramona Liza
authors.initials: RL
authors.lastname: Tillmann
authors.forename: Verena
authors.initials: V
authors.lastname: Schildgen
authors.forename: Oliver
authors.initials: O
authors.lastname: Schildgen
mesh_terms: D000375:Aging / Q000276:immunology*; D000818:Animals; D007109:Immunity; D029121:Metapneumovirus / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D016328:NF-kappa B / Q000032:analysis; D012136:Respiratory Syncytial Viruses / Q000276:immunology*; D012141:Respiratory Tract Infections / Q000276:immunology* / Q000821:virology*; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
chemical_list: D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha