Evidence for sap1 as a Virulence Factor in Burkholderia cepacia Complex

Abstract

Burkholderia cepacia complex (Bcc) is a consortium of at least 20 closely related Gram negative species that are a risk factor for cystic fibrosis (CF) patients. Previously in B. pseudomaelli, a hypothetical protein with no known function, was identified to be a novel virulence factor and involved in attachment. In this work, highly conserved homologs in Bcc K56-2 and LO6 were examined in multiple in vitro and in vivo models such as attachment to eukaryotic cell lines, biofilm attachment and formation, Caenorhabditis elegans survival model, Drosophila melanogaster feeding model, and mouse lung infection. We found that the deletion mutants had impaired attachment and biofilm formation, and significantly lower in vivo survival and replication, compared to the wildtype strains. Finally, C. elegans and mice infected with the mutants had better survival compared to wildtype infections, supporting the hypothesis that the protein surface attachment protein 1, or sap1, is a virulence factor.