title: Infection with human metapneumovirus predisposes mice to severe pneumococcal pneumonia.
abstract: Human metapneumovirus (hMPV) is a recently described paramyxovirus that causes respiratory tract infections. Prior clinical studies have highlighted the importance of respiratory viruses, such as influenza virus, in facilitating secondary bacterial infections and increasing host immunopathology. The objective of the present work was to evaluate the effects of initial viral infection with hMPV or influenza A virus followed by Streptococcus pneumoniae superinfection 5 days later in a murine model. Both groups of superinfected mice demonstrated significant weight loss (mean of 15%) and higher levels of airway obstruction (mean enhanced pause value of 2.7) compared to those of mice infected with hMPV, influenza virus, or pneumococcus alone. Bacterial counts increased from 5 x 10(2) CFU/lung in mice infected with pneumococcus only to 10(7) and 10(9) CFU/lung in mice with prior infections with hMPV and influenza A virus, respectively. A more pronounced interstitial and alveolar inflammation correlated with higher levels of inflammatory cytokines and chemokines such as interleukin-1alpha (IL-1alpha), IL-1beta, IL-6, IL-12, monocyte chemotactic protein 1, macrophage inflammatory protein 1alpha, KC, and granulocyte colony-stimulating factor, as well as greater expression of Toll-like receptor 2 (TLR2), TLR6, TLR7, and TLR13 in the lungs of superinfected animals compared to results for single infections, with similar immunological effects seen in both coinfection models. Prior infection with either hMPV or influenza A virus predisposes mice to severe pneumococcus infection.
authors.affiliation: Research Center in Infectious Diseases of the Centre Hospitalier Universitaire de Québec and Laval University, Quebec City, Quebec, Canada.
authors.forename: Irena
authors.initials: I
authors.lastname: Kukavica-Ibrulj
authors.forename: Marie-Eve
authors.initials: ME
authors.lastname: Hamelin
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Prince
authors.forename: Constance
authors.initials: C
authors.lastname: Gagnon
authors.forename: Yves
authors.initials: Y
authors.lastname: Bergeron
authors.forename: Michel G
authors.initials: MG
authors.lastname: Bergeron
authors.forename: Guy
authors.initials: G
authors.lastname: Boivin
mesh_terms: D000818:Animals; D002460:Cell Line; D004195:Disease Models, Animal; D004198:Disease Susceptibility; D005260:Female; D008168:Lung / Q000473:pathology; D029121:Metapneumovirus / Q000472:pathogenicity*; D051379:Mice; D008807:Mice, Inbred BALB C; D011018:Pneumonia, Pneumococcal / Q000382:microbiology* / Q000503:physiopathology / Q000821:virology