Editing Pilus (section)

== Virulence ==
Pili are responsible for virulence in the pathogenic strains of many bacteria, including [[Escherichia coli|''E. coli'']], ''[[Vibrio cholerae]]'', and many strains of ''[[Streptococcus]]''.<ref name=":0">{{Cite book|title=Bacterial Pili: Structure, Synthesis, and Role in Disease|last1=Craig|first1=Lisa|last2=Taylor|first2=Ronald|publisher=C.A.B. International|year=2014|isbn=978-1-78064-255-0|editor-last=Barocchi|editor-first=Michèle|pages=1–16|chapter=Chapter 1: The Vibrio cholerae Toxin Coregulated Pilus: Structure, Assembly, and Function with Implications for Vaccine Design|editor-last2=Telford|editor-first2=John}}</ref><ref>{{Cite book|title=Bacterial Pili: Structure, Synthesis, and Role in Disease|last1=Rinaudo|first1=Daniela|last2=Moschioni|first2=Monica|publisher=C.A.B. International|year=2014|isbn=978-1-78064-255-0|editor-last=Barocchi|editor-first=Michèle|pages=182–202|chapter=Chapter 13: Pilus-based Vaccine Development in Streptococci: Variability, Diversity, and Immunological Resposes|editor-last2=Telford|editor-first2=John}}</ref> This is because the presence of pili greatly enhances bacteria's ability to bind to body tissues, which then increases replication rates and ability to interact with the host organism.<ref name=":0" /> If a species of bacteria has multiple strains but only some are pathogenic, it is likely that the pathogenic strains will have pili while the nonpathogenic strains do not.<ref>{{Cite web|url=http://textbookofbacteriology.net/BSRP.html|title=Textbook of Bacteriology: Bacterial Structure in Relationship to Pathogenicity|last=Todar|first=Kenneth|website=Textbook of Bacteriology|access-date=24 November 2017}}</ref><ref name=":1">{{Cite book|title=Bacterial Pili: Structure, Synthesis, and Role in Disease|last1=Georgiadou|first1=Michaella|last2=Pelicic|first2=Vladimir|publisher=C.A.B. International|year=2014|isbn=978-1-78064-255-0|editor-last=Barocchi|editor-first=Michèle|pages=71–84|chapter=Chapter 5: Type IV Pili: Functions & Biogenesis|editor-last2=Telford|editor-first2=John}}</ref>

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 ''[[Escherichia coli|E. coli]]'', ''[[Bordetella pertussis]]'', ''Staphylococcus'' and ''Streptococcus'' bacteria. Their presence greatly enhances the bacteria's ability to attach to the host and cause disease.<ref name="pmid8790416">{{cite journal |vauthors=Connell I, Agace W, Klemm P, Schembri M, Mărild S, Svanborg C |title=Type 1 fimbrial expression enhances Escherichia coli virulence for the urinary tract |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=93 |issue=18 |pages=9827–32 |date=September 1996 |pmid=8790416 |pmc=38514 |doi= 10.1073/pnas.93.18.9827|bibcode=1996PNAS...93.9827C |doi-access=free }}</ref> Nonpathogenic strains of [[Vibrio cholerae|''V. cholerae'']] first evolved pili, allowing them to bind to human tissues and form [[microcolony|microcolonies]].<ref name=":0" /><ref name=":1" /> These pili then served as binding sites for the [[CTXφ bacteriophage|lysogenic bacteriophage]] that carries the disease-causing [[Cholera toxin|toxin]].<ref name=":0" /><ref name=":1" /> 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").<ref name=":0" />