We propose to continue testing our original hypothesis that virus infections alter the surfaces of host cells causing them to be selectively susceptible to adherence of potentially pathogenic bacteria. We have selected Staphylococcus aureus and human influenza A virus for continue study because staphylococcal pneumonia is a well-documented example of a life-threatening bacterial superinfection occurring in patients with complicated influenza. We propose to extend our previous studies, using a simple cell culture model system, to a much more complex animal model system. We have selected to use ferrets (Mustela putorius furo), which are small carnivores, because influenza in the ferret most resembles the disease in humans. One recent isolate of S. aureus from a patient who died with post-influenza staphylococcal pneumonia, and a human strain of influenza A/Hong Kong/1/68 (H3N2) virus are the primary infectious agents that will be used throughout the in vivo study. Influenza A virus-infection in ferrets will be studied using different doses of the virus and different routes of inoculation (intranasal, aerosol, and natural transmission). Virus-infected or sham-inoculated control ferrets will be sacrificed at specific time intervals; blood, respiratory washes, and respiratory tissues will be examined for virus distribution patterns and infectivity, sialoprotein content of mucin, the presence of nonspecific viral inhibitors, interferon levels, seroconversion, and hematologic changes. Staphylococcal infection in ferrets will also be studied using different doses of the bacteria and different routes of inoculation (intranasal, aerosol, and the 'carrier state') Respiratory tissues will be harvested at various time intervals for quantitative culture to determine the distribution and clearance of bacteria from different sites in the tract. The optimal conditions (dose, route of inoculation, stage of virus infection) for inducing a combined infection with influenza A virus and S. aureus will be determined, and the morbidity and mortality rates will be compared with those obtained with ferrets exposed to each agent alone. Lastly, an in vivo radioassay will be used to establish adherence patterns of radiolabeled bacteria to mucosal surfaces in the respiratory tract, and to determine the factors that affect adherence of bacteria to these surfaces.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI017242-08
Application #
3127043
Study Section
Bacteriology and Mycology Subcommittee 1 (BM)
Project Start
1980-08-01
Project End
1991-11-30
Budget Start
1988-12-01
Budget End
1989-11-30
Support Year
8
Fiscal Year
1989
Total Cost
Indirect Cost
Name
University of Texas Health Science Center San Antonio
Department
Type
Overall Medical
DUNS #
800772162
City
San Antonio
State
TX
Country
United States
Zip Code
78229
Sanford, B A; Thomas, V L; Ramsay, M A (1989) Binding of staphylococci to mucus in vivo and in vitro. Infect Immun 57:3735-42
Sanford, B A; Ramsay, M A (1989) In vivo localization of Staphylococcus aureus in nasal tissues of healthy and influenza A virus-infected ferrets. Proc Soc Exp Biol Med 191:163-9
Thomas, V L; Sanford, B A; Keogh, B S et al. (1989) Antibody response to Staphylococcus aureus surface proteins in rabbits with persistent osteomyelitis after treatment with demineralized bone implants. Infect Immun 57:404-12
Sanford, B A; Ramsay, M A (1987) Bacterial adherence to the upper respiratory tract of ferrets infected with influenza A virus. Proc Soc Exp Biol Med 185:120-8
Sanford, B A; Ramsay, M A (1986) Detection of staphylococcal membrane receptors on virus-infected cells by direct adhesin overlay. Infect Immun 52:671-5
Sanford, B A; Thomas, V L; Ramsay, M A et al. (1986) Characterization of clinical strains of Staphylococcus aureus associated with pneumonia. J Clin Microbiol 24:131-6
Sanford, B A; Davison, V E; Ramsay, M A (1986) Staphylococcus aureus adherence to influenza A virus-infected and control cell cultures: evidence for multiple adhesins. Proc Soc Exp Biol Med 181:104-11