PT  - JOURNAL ARTICLE
AU  - Amanda P. Smith
AU  - Lindey C. Lane
AU  - Tim van Opijnen
AU  - Stacie Woolard
AU  - Robert Carter
AU  - Amy Iverson
AU  - Corinna Burnham
AU  - Peter Vogel
AU  - Dana Roeber
AU  - Gabrielle Hochu
AU  - Michael D.L. Johnson
AU  - Jonathan A. McCullers
AU  - Jason Rosch
AU  - Amber M. Smith
TI  - Dynamic pneumococcal genetic adaptations support bacterial growth and inflammation during coinfection with influenza
AID  - 10.1101/659557
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 659557
4099  - http://biorxiv.org/content/early/2021/01/11/659557.short
4100  - http://biorxiv.org/content/early/2021/01/11/659557.full
AB  - Streptococcus pneumoniae (pneumococcus) is one of the primary bacterial pathogens that complicates influenza virus infections. These bacterial coinfections increase influenza-associated morbidity and mortality through a number of immunological and viral-mediated mechanisms, but the specific bacterial genes that contribute to post-influenza pathogenicity are not known. Here, we used genome-wide transposon mutagenesis (Tn-Seq) to reveal bacterial genes that confer improved fitness in influenza-infected hosts. The majority of the 32 identified genes are involved in bacterial metabolism, including nucleotide biosynthesis, amino acid biosynthesis, protein translation, and membrane transport. We generated single-gene deletion (SGD) mutants of five identified genes: SPD1414, SPD2047 (cbiO1), SPD0058 (purD), SPD1098, and SPD0822 (proB), to investigate their effect on in vivo fitness, disease severity, and host immune responses. Growth of SGD mutants was slightly attenuated in vitro and in vivo, but each still grew to high titers in the lungs of mock- and influenza-infected hosts. Despite high bacterial loads, mortality was significantly reduced or delayed with all SGD mutants. Time-dependent reductions in pulmonary neutrophils, inflammatory macrophages, and select proinflammatory cytokines and chemokines were also observed. Immunohistochemical staining further revealed that neutrophil phenotype and distribution was altered in the lungs of influenza-SGD coinfected animals. These studies demonstrate a critical role for specific bacterial genes and for bacterial metabolism in driving virulence and modulating immune function during influenza-associated bacterial pneumonia.Competing Interest StatementThe authors have declared no competing interest.