title: Sequential virus infections, bacterial superinfections, and fibrogenesis.
abstract: Parainfluenza 1 (Sendai) and influenza A virus pneumonitis cause severe lung damage, which, upon resolution, is followed by persistent alveolitis and parenchymal changes characterized by patchy consolidation and collagen deposition in the affected areas. To determine whether these long-term sequelae of the virus pneumonias are cumulative, mice were infected by aerosol inhalation with Sendai virus, influenza A virus, or Sendai followed 30 days later by influenza virus infection. At 90 days after the initial infection, mice were killed for assay of long-term parenchymal changes as quantitated lung hydroxyproline (Hpr) content, morphometric analysis, and total and differential lavage cell counts. Sendai virus infection did not alter the proliferation of influenza virus in the lungs as quantitated by infectious virus titers on Day 1, 3, 5, 7, 9, and 11 of influenza infection. At Day 90, lung Hpr content was cumulative in dual-infected mice, with a concomitant increase in the persistent alveolitis. To determine whether bacterial infections played a similar role in these long-term pulmonary sequelae, mice were infected by aerosol inhalation with either Staphylococcus aureus or Klebsiella pneumoniae or, during the course of influenza virus infection, superinfected with each of the bacteria. Sixty days after infection with K. pneumoniae alone, lung Hpr levels were significantly increased over those in noninfected control mice. Infection with S. aureus had no effect on the quantitated parameters of long-term lung damage. In influenza-infected mice superinfected with K. pneumoniae, lung Hpr content was significantly increased over that of S. aureus did not elevate any quantitated parameter of lung damage when compared with the virus alone.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Environmental Health Sciences, Johns Hopkins School of Hygiene and Public Health, Baltimore, Maryland 21205.
authors.forename: G J
authors.initials: GJ
authors.lastname: Jakab
mesh_terms: D000818:Animals; D005260:Female; D006909:Hydroxyproline / Q000032:analysis; D009980:Influenza A virus; D007710:Klebsiella Infections / Q000150:complications*; D007711:Klebsiella pneumoniae; D008168:Lung / Q000473:pathology; D051379:Mice; D009976:Orthomyxoviridae Infections / Q000150:complications; D010222:Parainfluenza Virus 1, Human; D018184:Paramyxoviridae Infections / Q000150:complications; D011023:Pneumonia, Staphylococcal / Q000150:complications*; D011024:Pneumonia, Viral / Q000150:complications*; D011658:Pulmonary Fibrosis / Q000209:etiology*; D015163:Superinfection
chemical_list: D006909:Hydroxyproline