title: Detection of severe human metapneumovirus infection by real-time polymerase chain reaction and histopathological assessment.
abstract: BACKGROUND
  Infections with common respiratory tract viruses can cause high mortality, especially in immunocompromised hosts, but the impact of human metapneumovirus (hMPV) in this setting was previously unknown.
  
  
  METHODS
  We evaluated consecutive bronchoalveolar lavage and bronchial wash fluid samples from 688 patients--72% were immunocompromised and were predominantly lung transplant recipients--for hMPV by use of quantitative real-time polymerase chain reaction (PCR), and positive results were correlated with clinical outcome and results of viral cultures, in situ hybridization, and lung histopathological assessment.
  
  
  RESULTS
  Six cases of hMPV infection were identified, and they had a similar frequency and occurred in a similar age range as other paramyxoviral infections. Four of 6 infections occurred in immunocompromised patients. Infection was confirmed by in situ hybridization for the viral nucleocapsid gene. Histopathological assessment of lung tissue samples showed acute and organizing injury, and smudge cell formation was distinct from findings in infections with other paramyxoviruses. Each patient with high titers of hMPV exhibited a complicated clinical course requiring prolonged hospitalization.
  
  
  CONCLUSIONS
  Our results provide in situ evidence of hMPV infection in humans and suggest that hMPV is a cause of clinically severe lower respiratory tract infection that can be detected during bronchoscopy by use of real-time PCR and routine histopathological assessment.
authors.affiliation: Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: Kaharu C
authors.initials: KC
authors.lastname: Sumino
authors.forename: Eugene
authors.initials: E
authors.lastname: Agapov
authors.forename: Richard A
authors.initials: RA
authors.lastname: Pierce
authors.forename: Elbert P
authors.initials: EP
authors.lastname: Trulock
authors.forename: John D
authors.initials: JD
authors.lastname: Pfeifer
authors.forename: Jon H
authors.initials: JH
authors.lastname: Ritter
authors.forename: Monique
authors.initials: M
authors.lastname: Gaudreault-Keener
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Storch
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Holtzman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001992:Bronchoalveolar Lavage Fluid; D005260:Female; D006801:Humans; D016867:Immunocompromised Host; D017403:In Situ Hybridization; D007223:Infant; D008168:Lung / Q000473:pathology; D008297:Male; D029121:Metapneumovirus / Q000235:genetics / Q000302:isolation & purification*; D008875:Middle Aged; D019251:Nucleocapsid / Q000235:genetics; D018184:Paramyxoviridae Infections / Q000175:diagnosis* / Q000473:pathology* / Q000821:virology; D016133:Polymerase Chain Reaction / Q000379:methods*