The development of attachment pili may then result in the development of further virulence traits. Fimbriae are one of the primary mechanisms of virulence for E. coli, Bordetella pertussis, Staphylococcus and Streptococcus bacteria. Their presence greatly enhances the bacteria's ability to attach to the host and cause disease. Nonpathogenic strains of V. cholerae first evolved pili, allowing them to bind to human tissues and form microcolonies. These pili then served as binding sites for the lysogenic bacteriophage that carries the disease-causing toxin. The gene for this toxin, once incorporated into the bacterium's genome, is expressed when the gene coding for the pilus is expressed (hence the name "toxin mediated pilus").
tHe dEvelopMENt OF AtTaChMEnt PiLi may THeN REsult in the DeVELopMEnt OF fuRther viRUlence traitS. fimbrIae are onE Of The pRIMary mEcHaNisms OF Virulence For e. coLi, borDetella pertusSIs, sTAPhYLococcus anD sTrEptOcoccus bactERia. tHeir pReseNcE GReAtly EnHAncEs tHE Bacteria'S AbIlIty To atTaCH tO ThE HosT aNd CAusE diSeAsE. nonpathogenic strAiNs of V. cholErAe fiRSt EvoLVed pIli, alLowINg TheM to BIND to hUMAN TisSuES and form MiCroCoLONIes. these pilI thEN servEd AS BInDinG sites For ThE LysOgeNiC bACteRIopHage THAt CaRRieS the disEAse-CAusiNg tOXIN. THe gene for This toxin, onCE inCOrpoRAtEd INTo THE bACterium'S genomE, iS exPresSed WhEn thE gEne coDIng FOR tHE pilus is eXPresseD (HenCe thE nAme "tOxIN mEDiatEd piLus").