title: Pretreatment of epithelial cells with live Streptococcus pneumoniae has no detectable effect on influenza A virus replication in vitro.
abstract: Influenza A virus (IAV) and Streptococcus pneumoniae (pneumococcus) are two major upper respiratory tract pathogens responsible for exacerbated disease in coinfected individuals. Despite several studies showing increased susceptibility to secondary bacterial infections following IAV infection, information on the direct effect of S. pneumoniae on IAV in vitro is unknown. This is an important area of investigation as S. pneumoniae is a common commensal of the human upper respiratory tract, present as an important coinfecting pathogen with IAV infection. A recent study showed that S. pneumoniae enhances human metapneumovirus infection in polarized bronchial epithelial cells in vitro. The aim of the current study was to determine whether treatment of epithelial cells with S. pneumoniae affects IAV replication using a standard immunofluorescence assay (IFA). For this study we used four IAV permissive epithelial cell lines including two human-derived cell lines, 12 pneumococcal strains including recent human clinical isolates which represent different genetic backgrounds and serotypes, and six IAV strains of varying genetic nature and pathogenic potential including the pandemic 2009 H1N1 virus. Our results suggested that pretreatment of MDCK cells with 7.5×10(6) colony-forming units (CFUs) of live S. pneumoniae resulted in gradual cell-death in a time-dependent manner (0.5 to 4 hr). But, pretreatment of cell lines with 7.5×10(5) and lower CFUs of S. pneumoniae had no detectable effect on either the morphology of cells or on the IAV replication. However, unlike in epithelial cell lines, due to influence of secreted host factors the effect of pneumococci on IAV replication may be different during coinfections in vivo in the human upper respiratory tract, and in vitro with primary human polarized bronchial epithelial cells.
authors.affiliation: College of Animal Science and Technology, Guangxi University, Nanning, China; Food Animal Health Research Program (FAHRP), OARDC, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, Ohio, United States of America.
authors.forename: Kang
authors.initials: K
authors.lastname: Ouyang
authors.affiliation: Center for Microbial Pathogenesis, Nationwide Children's Hospital, Columbus, Ohio, United States of America.
authors.forename: Shireen A
authors.initials: SA
authors.lastname: Woodiga
authors.affiliation: Food Animal Health Research Program (FAHRP), OARDC, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, Ohio, United States of America.
authors.forename: Varun
authors.initials: V
authors.lastname: Dwivedi
authors.affiliation: Center for Microbial Pathogenesis, Nationwide Children's Hospital, Columbus, Ohio, United States of America; Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Buckwalter
authors.affiliation: Center for Microbial Pathogenesis, Nationwide Children's Hospital, Columbus, Ohio, United States of America.
authors.forename: Anirudh K
authors.initials: AK
authors.lastname: Singh
authors.affiliation: Food Animal Health Research Program (FAHRP), OARDC, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, Ohio, United States of America.
authors.forename: Basavaraj
authors.initials: B
authors.lastname: Binjawadagi
authors.affiliation: Food Animal Health Research Program (FAHRP), OARDC, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, Ohio, United States of America.
authors.forename: Jagadish
authors.initials: J
authors.lastname: Hiremath
authors.affiliation: Food Animal Health Research Program (FAHRP), OARDC, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, Ohio, United States of America.
authors.forename: Cordelia
authors.initials: C
authors.lastname: Manickam
authors.affiliation: Food Animal Health Research Program (FAHRP), OARDC, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, Ohio, United States of America.
authors.forename: Rose
authors.initials: R
authors.lastname: Schleappi
authors.affiliation: Food Animal Health Research Program (FAHRP), OARDC, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, Ohio, United States of America.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Khatri
authors.affiliation: College of Animal Science and Technology, Guangxi University, Nanning, China.
authors.forename: Jianmin
authors.initials: J
authors.lastname: Wu
authors.affiliation: Center for Microbial Pathogenesis, Nationwide Children's Hospital, Columbus, Ohio, United States of America; Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: King
authors.affiliation: Food Animal Health Research Program (FAHRP), OARDC, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, Ohio, United States of America.
authors.forename: Gourapura J
authors.initials: GJ
authors.lastname: Renukaradhya
mesh_terms: D000818:Animals; D002138:Calibration; D004285:Dogs; D004847:Epithelial Cells / Q000382:microbiology*; D066298:In Vitro Techniques; D009980:Influenza A virus / Q000502:physiology*; D061985:Madin Darby Canine Kidney Cells; D008856:Microscopy, Fluorescence; D013296:Streptococcus pneumoniae / Q000145:classification / Q000502:physiology*; D014779:Virus Replication