title: Staphylococcus aureus adherence to influenza A virus-infected and control cell cultures: evidence for multiple adhesins.
abstract: During major epidemics with influenza, there is an increased number of pneumonias due to Staphylococcus aureus with a subsequent high mortality rate. We have postulated that influenza A virus infection of host cells promotes the adherence of S. aureus ultimately resulting in bacterial superinfection. In the present study we compared the adherence of seven strains of 3H-labeled S. aureus to Madin-Darby canine kidney (MDCK) cell monolayers, uninfected and infected with influenza A/FM/1/47 virus. Test strains included: Cowan I; a Cowan I protein A-deficient mutant (PA-); EMS, a protein A and clumping factor-deficient mutant; HSmR; 52A5, a teichoic acid-deficient mutant of HSmR; M, an encapsulated strain; and, No. 1071, a clinical isolate. By radioassay, six of the seven strains demonstrated significantly enhanced adherence to virus-infected cell monolayers compared to uninfected controls; only the M strain was adherence negative. Surface hydrophobicity of the staphylococci did not correlate with their ability to adhere. Four strains of labeled staphylococci (Cowan I, PA-, EMS, and No. 1071), untreated or treated with 2.5% trypsin, 1.25% protease, or by autoclaving, were tested in the radioassay. Protease treatment, which was more effective than trypsin treatment, reduced adherence of all four test strains by 74-96%. Results of heat treatment suggested the presence of both thermolabile and thermostable adhesins. Staphylococcal thermal extracts, profiled by anion-exchange HPLC, were used to pretreat monolayers in a blocking radioassay. Adherence was decreased to control cells (9-78%) and to virus-infected cells (56-90%). The data suggest that multiple distinct surface proteins mediate the binding of S. aureus to uninfected and influenza A virus-infected cells.
mesh_terms: D000268:Adhesiveness; D000818:Animals; D000954:Antigens, Surface / Q000032:analysis; D001426:Bacterial Proteins / Q000032:analysis*; D002478:Cells, Cultured; D004285:Dogs; D006358:Hot Temperature; D009980:Influenza A virus; D008070:Lipopolysaccharides; D009976:Orthomyxoviridae Infections / Q000382:microbiology*; D010712:Phosphatidic Acids / Q000502:physiology; D013211:Staphylococcus aureus / Q000032:analysis / Q000502:physiology*; D013682:Teichoic Acids / Q000502:physiology; D014357:Trypsin / Q000494:pharmacology
chemical_list: D000954:Antigens, Surface; D001426:Bacterial Proteins; D008070:Lipopolysaccharides; D010712:Phosphatidic Acids; D013682:Teichoic Acids; C009900:lipoteichoic acid; D014357:Trypsin