Editing Pathogenicity island (section)

'''Pathogenicity islands''' ('''PAIs'''), as termed in 1990, are a distinct class of [[genomic island]]s acquired by [[microorganisms]] through [[horizontal gene transfer]].<ref>{{cite journal | last1 = Hacker | first1 = J | last2 = Bender | first2 = L | last3 = Ott | first3 = M | last4 = Wingender | first4 = J | last5 = Lund | first5 = B | display-authors = 3 | year = 1990 | title = Deletions of chro- mosomal regions coding for fimbriae and hemolysins occur in vivo and in vitro in various extraintestinal Escherichia coli iso- lates | journal = Microb. Pathog. | volume = 8 | issue = 3| pages = 213–25 | pmid = 1974320 | doi = 10.1016/0882-4010(90)90048-U }}</ref><ref name="Hacker_2000">{{cite journal |last1=Hacker |first1=J |last2=Kaper |first2=JB |year=2000 |title=Pathogenicity Islands and the Evolution of Microbes |journal=Annual Review of Microbiology |volume=54 |pages=641–679 |pmid=11018140 |doi=10.1146/annurev.micro.54.1.641 |s2cid=1945976 |issn=0066-4227}}</ref> Pathogenicity islands are found in both animal and plant pathogens.<ref name="Hacker_2000"/> Additionally, PAIs are found in both [[Gram-positive bacteria|gram-positive]] and [[gram-negative bacteria]].<ref name="Hacker_2000"/> They are transferred through horizontal gene transfer events such as transfer by a [[plasmid]], [[bacteriophage|phage]], or conjugative [[transposon]].<ref name="Hacker_1997">{{cite journal |last1=Hacker |first1=J. |last2=Blum-Oehler |first2=G. |last3=Muhldorfer |first3=I. |last4=Tschape |first4=H. |year=1997 |title=Pathogenecity islands of virulent bacteria: structure, function and impact on microbial evolution |journal=Molecular Microbiology |volume=23 |issue=6| pages=1089–1097 |doi=10.1046/j.1365-2958.1997.3101672.x |pmid=9106201 |s2cid=27524815 |doi-access=free}}</ref> Although the general makeup of pathogenicity islands (PAIs) might vary throughout bacterial pathogen strains, all PAIs are known to have characteristics with all genomic islands, which includes virulence genes, functional mobility elements, and areas of homology to tRNA genes and direct repeats.<ref name="Hacker_2000" /><ref>{{Cite journal |last1=Gal-Mor |first1=Ohad |last2=Finlay |first2=B. Brett |date=2006 |title=Pathogenicity islands: a molecular toolbox for bacterial virulence |journal=Cellular Microbiology |language=en |volume=8 |issue=11 |pages=1707–1719 |doi=10.1111/j.1462-5822.2006.00794.x |doi-access=free |pmid=16939533 |issn=1462-5822}}</ref> Therefore, PAIs enables microorganisms to induce disease and also contribute to microorganisms' ability to evolve. The spread of antibiotic resistance and, more generally, the conversion of non-pathogenic strains in natural environments to strains that infect animal and plant hosts with disease are two examples of the evolutionary and ecological changes brought about by the transmission and acquisition of PAIs among bacterial species.<ref name=":1" /> However, It is impossible to overlook their impact on bacterial evolution, though, since if a PAI is acquired and is stably absorbed, it can irreversibly change the [[bacterial genome]].<ref name="Hacker_2000" /><ref name="Hacker_1997" />

One species of bacteria may have more than one PAI. For example, ''Salmonella'' has at least five.<ref>{{Cite journal |last=Marcus |first=Sandra L. |last2=Brumell |first2=John H. |last3=Pfeifer |first3=Cheryl G. |last4=Finlay |first4=B. Brett |date=2000-02-01 |title=Salmonella pathogenicity islands: big virulence in small packages |url=https://linkinghub.elsevier.com/retrieve/pii/S1286457900002732 |journal=Microbes and Infection |volume=2 |issue=2 |pages=145–156 |doi=10.1016/S1286-4579(00)00273-2 |issn=1286-4579|url-access=subscription }}</ref> An analogous genomic structure in [[rhizobia]] is termed a ''[[symbiosis island]]''.