Human papillomavirus pathophysiology: Difference between revisions

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__NOTOC__
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{{Human papillomavirus}}
{{Human papillomavirus}}
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{{CMG}}{{AE}}{{AA}},{{MehdiP}}


== Overview ==
== Overview ==
[[Human papilloma virus]] is usually transmitted via the sexual route to the human host.<ref name="pmid18507898">{{cite journal| author=Hernandez BY, Wilkens LR, Zhu X, Thompson P, McDuffie K, Shvetsov YB et al.| title=Transmission of human papillomavirus in heterosexual couples. | journal=Emerg Infect Dis | year= 2008 | volume= 14 | issue= 6 | pages= 888-94 | pmid=18507898 | doi=10.3201/eid1406.070616 | pmc=2600292 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18507898  }} </ref> [[HPV]] life cycle is linked to epithelial [[differentiation]] and maturation of host [[keratinocytes]], with [[transcription]] of specific gene products at every level.<ref name="pmid15753007">{{cite journal| author=Doorbar J| title=The papillomavirus life cycle. | journal=J Clin Virol | year= 2005 | volume= 32 Suppl 1 | issue=  | pages= S7-15 | pmid=15753007 | doi=10.1016/j.jcv.2004.12.006 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15753007  }} </ref><ref name="pmid23199966">{{cite journal| author=Doorbar J, Quint W, Banks L, Bravo IG, Stoler M, Broker TR et al.| title=The biology and life-cycle of human papillomaviruses. | journal=Vaccine | year= 2012 | volume= 30 Suppl 5 | issue=  | pages= F55-70 | pmid=23199966 | doi=10.1016/j.vaccine.2012.06.083 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23199966  }} </ref> The pathogenesis of [[HPV]] infection causing [[cancer]] is mainly linked to high risk types of [[HPV]] (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and 68). E6 and E7 protein products of HPV interact with two important cell cycle regulatory protiens, [[P53]] and [[Rb]] proteins of host cell, causing unchecked [[cell cycle|cellular replication]] accumulating [[mutations]] leading to [[cancer]].<ref name="pmid20592731">{{cite journal| author=Moody CA, Laimins LA| title=Human papillomavirus oncoproteins: pathways to transformation. | journal=Nat Rev Cancer | year= 2010 | volume= 10 | issue= 8 | pages= 550-60 | pmid=20592731 | doi=10.1038/nrc2886 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20592731  }} </ref><ref name="pmid2823272">{{cite journal| author=Masuda H, Miller C, Koeffler HP, Battifora H, Cline MJ| title=Rearrangement of the p53 gene in human osteogenic sarcomas. | journal=Proc Natl Acad Sci U S A | year= 1987 | volume= 84 | issue= 21 | pages= 7716-9 | pmid=2823272 | doi= | pmc=299371 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=2823272  }} </ref><ref name="pmid8380917">{{cite journal| author=Tommasino M, Adamczewski JP, Carlotti F, Barth CF, Manetti R, Contorni M et al.| title=HPV16 E7 protein associates with the protein kinase p33CDK2 and cyclin A. | journal=Oncogene | year= 1993 | volume= 8 | issue= 1 | pages= 195-202 | pmid=8380917 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8380917  }} </ref>
==Pathophysiology==
==Pathophysiology==
===Transmission===
===Transmission===
*Human papilloma virus is usually transmitted via the sexual route to the human host.
*[[Human papilloma virus]] is usually transmitted via the sexual route to the human host.<ref name="pmid18507898">{{cite journal| author=Hernandez BY, Wilkens LR, Zhu X, Thompson P, McDuffie K, Shvetsov YB et al.| title=Transmission of human papillomavirus in heterosexual couples. | journal=Emerg Infect Dis | year= 2008 | volume= 14 | issue= 6 | pages= 888-94 | pmid=18507898 | doi=10.3201/eid1406.070616 | pmc=2600292 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18507898  }} </ref>
*Different types of HPV has a predilection for different types of epithelial tissue.
*Different types of [[HPV]] has a predilection for different types of epithelial tissue.<ref name="pmid15634997">{{cite journal| author=Rintala MA, Grénman SE, Puranen MH, Isolauri E, Ekblad U, Kero PO et al.| title=Transmission of high-risk human papillomavirus (HPV) between parents and infant: a prospective study of HPV in families in Finland. | journal=J Clin Microbiol | year= 2005 | volume= 43 | issue= 1 | pages= 376-81 | pmid=15634997 | doi=10.1128/JCM.43.1.376-381.2005 | pmc=540188 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15634997  }} </ref>
 
===HPV life cycle===
===HPV life cycle===
*HPV life cycle is linked to epithelial [[differentiation]] and maturation of host keratinocytes, with [[transcription]] of specific gene products at every level.
*[[HPV]] life cycle is linked to epithelial [[differentiation]] and maturation of host [[keratinocytes]], with [[transcription]] of specific gene products at every level.<ref name="pmid15753007">{{cite journal| author=Doorbar J| title=The papillomavirus life cycle. | journal=J Clin Virol | year= 2005 | volume= 32 Suppl 1 | issue=  | pages= S7-15 | pmid=15753007 | doi=10.1016/j.jcv.2004.12.006 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15753007  }} </ref><ref name="pmid23199966">{{cite journal| author=Doorbar J, Quint W, Banks L, Bravo IG, Stoler M, Broker TR et al.| title=The biology and life-cycle of human papillomaviruses. | journal=Vaccine | year= 2012 | volume= 30 Suppl 5 | issue=  | pages= F55-70 | pmid=23199966 | doi=10.1016/j.vaccine.2012.06.083 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23199966  }} </ref><ref name="pmid17627064">{{cite journal| author=Doorbar J| title=Papillomavirus life cycle organization and biomarker selection. | journal=Dis Markers | year= 2007 | volume= 23 | issue= 4 | pages= 297-313 | pmid=17627064 | doi= | pmc=3851388 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17627064  }} </ref>
*HPV primarily infects basal cell layer of stratified squamous keratinised epithelium.
*[[HPV]] primarily infects basal cell layer of [[stratified squamous keratinised epithelium]].<ref name="pmid19920181">{{cite journal| author=Kines RC, Thompson CD, Lowy DR, Schiller JT, Day PM| title=The initial steps leading to papillomavirus infection occur on the basement membrane prior to cell surface binding. | journal=Proc Natl Acad Sci U S A | year= 2009 | volume= 106 | issue= 48 | pages= 20458-63 | pmid=19920181 | doi=10.1073/pnas.0908502106 | pmc=2787115 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19920181  }} </ref>
*Following transmission, the HPV uses the microabrasions to enter the basal stem cells via tissue specific [[heparan sulfate]] proteoglycans through clathrin-mediated [[endocytosis]] and/or caveolin-mediated endocytosis depending on the type of HPV.     
*Following transmission, the [[HPV]] uses the microabrasions to enter the basal stem cells via tissue specific [[heparan sulfate]] proteoglycans through [[clathrin-mediated]] [[endocytosis]] and/or caveolin-mediated endocytosis depending on the type of [[HPV]].<ref name="pmid19073722">{{cite journal| author=Johnson KM, Kines RC, Roberts JN, Lowy DR, Schiller JT, Day PM| title=Role of heparan sulfate in attachment to and infection of the murine female genital tract by human papillomavirus. | journal=J Virol | year= 2009 | volume= 83 | issue= 5 | pages= 2067-74 | pmid=19073722 | doi=10.1128/JVI.02190-08 | pmc=2643729 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19073722  }} </ref>    
*It than undergoes viral uncoating and viral DNA genome is than transported to nucleus maintaining a low copy number 10-200 viral genomes per cell (episome form)
*It than undergoes viral uncoating and viral DNA genome is than transported to nucleus maintaining a low copy number 10-200 viral genomes per cell (episome form).<ref name="pmid1850010">{{cite journal| author=Bedell MA, Hudson JB, Golub TR, Turyk ME, Hosken M, Wilbanks GD et al.| title=Amplification of human papillomavirus genomes in vitro is dependent on epithelial differentiation. | journal=J Virol | year= 1991 | volume= 65 | issue= 5 | pages= 2254-60 | pmid=1850010 | doi= | pmc=240574 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1850010  }} </ref>
*A sophisticated transcriptional cascade then occurs as the host keratinocyte begins to divide and become increasingly differentiated in the upper layers of the epithelium.
*A sophisticated transcriptional cascade then occurs as the host [[keratinocyte]] begins to divide and become increasingly differentiated in the upper layers of the epithelium.
*HPV uses host DNA replicative machinery to multiply as it lacks [[DNA polymerase]] activity.
*[[HPV]] uses host [[DNA]] replicative machinery to multiply as it lacks [[DNA polymerase]] activity.
*Specific viral genes are transcribed at every level of [[keratinocyte]] differention.  
*Specific viral genes are transcribed at every level of [[keratinocyte]] differention.  
*Early proteins: E1, E2, E3, E4, E5, E6 and E7 proteins are synthesized primarily in middle layers, for reactivation of replication process in the differentiated cells.   
*Early proteins: E1, E2, E3, E4, E5, E6 and E7 proteins are synthesized primarily in middle layers, for reactivation of replication process in the differentiated cells.   
*Late proteins: L1, L2 proteins are transcribed in the most superficial layers for [[virion]] assesmbly, release and reinfection, as they code for [[capsid]] proteins.
*Late proteins: L1, L2 proteins are transcribed in the most superficial layers for [[virion]] assesmbly, release and reinfection, as they code for [[capsid]] proteins.<ref name="pmid12560332">{{cite journal| author=Yang R, Yutzy WH, Viscidi RP, Roden RB| title=Interaction of L2 with beta-actin directs intracellular transport of papillomavirus and infection. | journal=J Biol Chem | year= 2003 | volume= 278 | issue= 14 | pages= 12546-53 | pmid=12560332 | doi=10.1074/jbc.M208691200 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12560332  }} </ref>
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[[Image:HPV-16 genome organization.png|240px|thumb|left|Genome organization of human papillomavirus type 16, one of the subtypes known to cause cervical cancer. (E1-E7 early genes, L1-L2 late genes: capsid)]]
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==Pathogenesis of HPV induced cancers==
==Pathogenesis of HPV induced cancers==
The pathogenesis of HPV infection causing cancer is mainly linked to high risk types of HPV (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and 68). Following HPV proteins play a significant role in the development of cancers associated with HPV.
The pathogenesis of [[HPV]] infection causing cancer is mainly linked to high risk types of HPV (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and 68). Following [[HPV]] proteins play a significant role in the development of cancers associated with HPV.<ref name="pmid20952254">{{cite journal| author=de Sanjose S, Quint WG, Alemany L, Geraets DT, Klaustermeier JE, Lloveras B et al.| title=Human papillomavirus genotype attribution in invasive cervical cancer: a retrospective cross-sectional worldwide study. | journal=Lancet Oncol | year= 2010 | volume= 11 | issue= 11 | pages= 1048-56 | pmid=20952254 | doi=10.1016/S1470-2045(10)70230-8 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20952254  }} </ref>
===E6 and E7 proteins===
===E6 and E7 proteins===
E6 and E7 protein products of HPV interact with two important cell cycle regulatory protiens, P53 and Rb proteins of host cell, causing unchecked cellular replication accumulating mutations leading to cancer.
E6 and E7 protein products of HPV interact with two important [[cell cycle]] regulatory protiens, [[P53]] and [[Rb]] proteins of host cell, causing unchecked cellular replication accumulating [[mutations]] leading to cancer.<ref name="pmid20592731">{{cite journal| author=Moody CA, Laimins LA| title=Human papillomavirus oncoproteins: pathways to transformation. | journal=Nat Rev Cancer | year= 2010 | volume= 10 | issue= 8 | pages= 550-60 | pmid=20592731 | doi=10.1038/nrc2886 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20592731  }} </ref>
*'''Inhibition of P53'''
*'''Inhibition of P53'''
:[[P53]] protein is a cellular check point at [[G0/G1]] to S phase of [[cell cycle]] and is also responsible for cell apoptosis for unrepaired DNA mutations. E6 protein binds P53 which results in degradation of P53, leaving cell without any check for mutations and unregulated cell
:[[P53]] protein is a cellular check point at [[G0/G1]] to S phase of [[cell cycle]] and is also responsible for cell [[apoptosis]] for unrepaired DNA mutations. E6 protein binds [[P53]] which results in degradation of [[P53]], leaving cell without any check for mutations and unregulated cell.<ref name="pmid2823272">{{cite journal| author=Masuda H, Miller C, Koeffler HP, Battifora H, Cline MJ| title=Rearrangement of the p53 gene in human osteogenic sarcomas. | journal=Proc Natl Acad Sci U S A | year= 1987 | volume= 84 | issue= 21 | pages= 7716-9 | pmid=2823272 | doi= | pmc=299371 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=2823272  }} </ref><ref name="pmid2642977">{{cite journal| author=Hinds P, Finlay C, Levine AJ| title=Mutation is required to activate the p53 gene for cooperation with the ras oncogene and transformation. | journal=J Virol | year= 1989 | volume= 63 | issue= 2 | pages= 739-46 | pmid=2642977 | doi= | pmc=247745 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=2642977  }} </ref>
:growth.  
:growth.<ref name="pmid8221889">{{cite journal| author=Scheffner M, Huibregtse JM, Vierstra RD, Howley PM| title=The HPV-16 E6 and E6-AP complex functions as a ubiquitin-protein ligase in the ubiquitination of p53. | journal=Cell | year= 1993 | volume= 75 | issue= 3 | pages= 495-505 | pmid=8221889 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8221889  }} </ref><ref name="pmid7671255">{{cite journal| author=Havre PA, Yuan J, Hedrick L, Cho KR, Glazer PM| title=p53 inactivation by HPV16 E6 results in increased mutagenesis in human cells. | journal=Cancer Res | year= 1995 | volume= 55 | issue= 19 | pages= 4420-4 | pmid=7671255 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7671255  }} </ref><ref name="pmid2157286">{{cite journal| author=Werness BA, Levine AJ, Howley PM| title=Association of human papillomavirus types 16 and 18 E6 proteins with p53. | journal=Science | year= 1990 | volume= 248 | issue= 4951 | pages= 76-9 | pmid=2157286 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=2157286  }} </ref><ref name="pmid9426696">{{cite journal| author=Magal SS, Jackman A, Pei XF, Schlegel R, Sherman L| title=Induction of apoptosis in human keratinocytes containing mutated p53 alleles and its inhibition by both the E6 and E7 oncoproteins. | journal=Int J Cancer | year= 1998 | volume= 75 | issue= 1 | pages= 96-104 | pmid=9426696 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9426696  }} </ref><ref name="pmid8183918">{{cite journal| author=Demers GW, Foster SA, Halbert CL, Galloway DA| title=Growth arrest by induction of p53 in DNA damaged keratinocytes is bypassed by human papillomavirus 16 E7. | journal=Proc Natl Acad Sci U S A | year= 1994 | volume= 91 | issue= 10 | pages= 4382-6 | pmid=8183918 | doi= | pmc=43789 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8183918  }} </ref>
*'''Inhibition of Rb protein'''
*'''Inhibition of Rb protein'''
:Rb protein is negative regulator of cell growth. It binds E2F [[transcription factor]] which controls [[DNA replication]] and [[cyclin]] protein induced entering of cell into S phase of cell cycle. E7 protein binds Rb/E2F, releasing E2F from the inhibitory effect of Rb causing increased cyclin induced entry of cell into [[S phase]] of cell cycle, resulting in increased replication rate of cells accumulating mutations.  
:[[Rb]] protein is negative regulator of cell growth. It binds E2F [[transcription factor]] which controls [[DNA replication]] and [[cyclin]] protein induced entering of cell into S phase of [[cell cycle]]. E7 protein binds Rb/E2F, releasing E2F from the inhibitory effect of Rb causing increased cyclin induced entry of cell into [[S phase]] of cell cycle, resulting in increased replication rate of cells accumulating mutations.<ref name="pmid8183918">{{cite journal| author=Demers GW, Foster SA, Halbert CL, Galloway DA| title=Growth arrest by induction of p53 in DNA damaged keratinocytes is bypassed by human papillomavirus 16 E7. | journal=Proc Natl Acad Sci U S A | year= 1994 | volume= 91 | issue= 10 | pages= 4382-6 | pmid=8183918 | doi= | pmc=43789 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8183918  }} </ref><ref name="pmid1323816">{{cite journal| author=Pagano M, Dürst M, Joswig S, Draetta G, Jansen-Dürr P| title=Binding of the human E2F transcription factor to the retinoblastoma protein but not to cyclin A is abolished in HPV-16-immortalized cells. | journal=Oncogene | year= 1992 | volume= 7 | issue= 9 | pages= 1681-6 | pmid=1323816 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1323816  }} </ref><ref name="pmid8380917">{{cite journal| author=Tommasino M, Adamczewski JP, Carlotti F, Barth CF, Manetti R, Contorni M et al.| title=HPV16 E7 protein associates with the protein kinase p33CDK2 and cyclin A. | journal=Oncogene | year= 1993 | volume= 8 | issue= 1 | pages= 195-202 | pmid=8380917 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8380917  }} </ref><ref name="pmid10228159">{{cite journal| author=Brehm A, Nielsen SJ, Miska EA, McCance DJ, Reid JL, Bannister AJ et al.| title=The E7 oncoprotein associates with Mi2 and histone deacetylase activity to promote cell growth. | journal=EMBO J | year= 1999 | volume= 18 | issue= 9 | pages= 2449-58 | pmid=10228159 | doi=10.1093/emboj/18.9.2449 | pmc=1171327 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10228159  }} </ref>
 
=== HPV-Induced Diseases ===
=== HPV-Induced Diseases ===
{| class="wikitable" style="margin:1em; float:center;"
{| class="wikitable" style="margin:1em; float:center;"
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| 6, 7, 11, 16, 32
|}
|}
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=== Genital Warts ===
[[Image:condyloma accumulata.jpg|thumb|200px|left|Condyloma Accumulata (HPV)<ref>http://picasaweb.google.com/mcmumbi/USMLEIIImages/photo#5089143144241737026</ref>]]
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[[Genital wart|Genital or anal warts]] (condylomata acuminata or venereal warts) are the most easily recognized sign of genital HPV infection. Although a wide variety of HPV types can cause genital warts, types 6 and 11 account for about 90% of all cases.<ref>{{cite journal |author=Greer CE, Wheeler CM, Ladner MB, ''et al'' |title=Human papillomavirus (HPV) type distribution and serological response to HPV type 6 virus-like particles in patients with genital warts |journal=J. Clin. Microbiol. |volume=33 |issue=8 |pages=2058-63 |year=1995 |pmid=7559948 |doi=}}</ref><ref>{{cite web | author = Gearheart PA, Randall TC, Buckley RM Jr | year = 2004 | url = http://www.emedicine.com/med/topic1037.htm | title = Human Papillomavirus | publisher = eMedicine}}</ref>


Most people who acquire genital wart-associated HPV types clear the infection rapidly without ever developing warts or any other symptoms. People may transmit the virus to others even if they don't display overt symptoms of infection. However, in the vast majority of cases, this is not a cause for concern if proper tests are routinely administered.
==References==


HPV types that tend to cause genital warts are '''not''' the same ones that cause cervical cancer. However, since an individual can be infected with multiple types of HPV, the presence of warts does not rule out the possibility of high risk types of the virus also being present.
{{Reflist|2}}


Condyloma accumulata is another form of genital warts.
{{WH}}
 
{{WS}}
=== Cancer ===
{{seealso|Cervical cancer}}
[[Image:Cases of HPV cancers graph.png|thumb|left|350px|HPV-induced cancers]]
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About a dozen HPV types (including types 16, 18, 31 and 45) are called "high-risk" types because they can lead to [[cervical cancer]], as well as [[anal cancer]], [[vulvar cancer]], and [[penile cancer]].<ref>{{cite journal |author=Parkin DM |title=The global health burden of infection-associated cancers in the year 2002 |journal=Int. J. Cancer |volume=118 |issue=12 |pages=3030-44 |year=2006 |pmid=16404738 |doi=10.1002/ijc.21731}}</ref> Several types of HPV, particularly type 16, have been found to be associated with oropharyngeal squamous-cell carcinoma, a form of [[head and neck cancer]].<ref name="D'Souza_2007">{{cite journal |author=D'Souza G, Kreimer AR, Viscidi R, ''et al'' |title=Case-control study of human papillomavirus and oropharyngeal cancer |journal=N. Engl. J. Med. |volume=356 |issue=19 |pages=1944-56 |year=2007 |pmid=17494927 |doi=10.1056/NEJMoa065497 | url = http://content.nejm.org/cgi/content/full/356/19/1944}}</ref>  HPV-induced cancers often have viral sequences integrated into the cellular DNA. Some of the HPV "early" genes, such as E6 and E7, are known to act as [[oncogene]]s that promote tumor growth and [[malignant|malignant transformation]].
 
The [[p53]] protein prevents cell growth in the presence of DNA damage primarily through the [[BAX]] domain, which blocks the anti-apoptotic effects of the mitochondrial [[BCL-2]] receptor. In addition, [[p53]] also upregulates the [[p21]] protein, which blocks the formation of the [[Cyclin D/Cdk4]] complex, thereby preventing the phosphorylation of [[RB]] and, in turn, halting cell cycle progression by preventing the activation of [[E2F]]. In short, p53 is a tumor suppressor gene that arrests the cell cycle when there is DNA damage. The E6 and E7 proteins work by inhibiting tumor suppression genes involved in that pathway: E6 inhibits [[p53]], while E7 inhibits [[p53]], [[p21]], and [[RB]].
 
[[Image:HPV-16 genome organization.png|240px|thumb|left|Genome organization of human papillomavirus type 16, one of the subtypes known to cause cervical cancer. (E1-E7 early genes, L1-L2 late genes: capsid)]]
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A history of infection with one or more high-risk HPV types is believed to be a prerequisite for the development of cervical cancer (the vast majority of HPV infections are not high risk); according to the [[American Cancer Society]], women with no history of the virus do not develop this type of cancer. However, most HPV infections are cleared rapidly by the immune system and do not progress to cervical cancer. Because the process of transforming normal cervical cells into cancerous ones is slow, cancer occurs in people who have been infected with HPV for a long time, usually over a decade or more.<ref>Greenblatt R.J. 2005. [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T5D-4H6P7Y9-1&_user=10&_handle=V-WA-A-W-W-MsSAYZA-UUA-U-AABAVZDCWU-AAWEUVYBWU-BEAYVEYEY-W-U&_fmt=summary&_coverDate=09%2F15%2F2005&_rdoc=1&_orig=browse&_srch=%23toc%235000%232005%23999729981%23607092!&_cdi=5000&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=42b5289fd6b206fd7ae9269741210c39 Human papillomaviruses: Diseases, diagnosis, and a possible vaccine]. ''Clinical Microbiology Newsletter'', 27(18), 139-145. Abstract available.</ref><ref name=Sinal_2005>{{cite journal |author=Sinal SH, Woods CR |title=Human papillomavirus infections of the genital and respiratory tracts in young children |journal=Seminars in pediatric infectious diseases |volume=16 |issue=4 |pages=306-16 |year=2005 |pmid=16210110 |doi=10.1053/j.spid.2005.06.010}}</ref>
 
Sexually transmitted HPVs also cause a major fraction of [[anal cancer]]s and approximately 25% of cancers of the mouth and upper throat (known as the oropharynx) (see figure). The latter commonly present in the tonsil area and HPV is linked to the increase in oral cancers in non-smokers.<ref>{{cite journal |author=Gillison ML, Koch WM, Capone RB, ''et al'' |title=Evidence for a causal association between human papillomavirus and a subset of head and neck cancers |journal=J. Natl. Cancer Inst. |volume=92 |issue=9 |pages=709-20 |year=2000 |pmid=10793107 |doi=}}</ref><ref>{{cite journal |author=Gillison ML |title=Human papillomavirus and prognosis of oropharyngeal squamous cell carcinoma: implications for clinical research in head and neck cancers |journal=J. Clin. Oncol. |volume=24 |issue=36 |pages=5623-5 |year=2006 |pmid=17179099 |doi=10.1200/JCO.2006.07.1829}}</ref> Engaging in [[anal sex]] or [[oral sex]] with an HPV-infected partner may increase the risk of developing these types of cancers.<ref name="D'Souza_2007" />
 
=== Respiratory Papillomatosis ===
 
HPV types 6 and 11 can cause a rare condition known as recurrent [[Laryngeal papillomatosis|respiratory papillomatosis]], in which warts form on the larynx or other areas of the respiratory tract.<ref>{{cite journal |author=Wu R, Sun S, Steinberg BM |title=Requirement of STAT3 activation for differentiation of mucosal stratified squamous epithelium |journal=Mol. Med. |volume=9 |issue=3-4 |pages=77-84 |year=2003 |pmid=12865943 |doi=}}</ref><ref name=Sinal_2005 />
 
These warts can recur frequently, may require repetitive surgery, may interfere with breathing, and in extremely rare cases can progress to cancer.<ref>{{cite journal |author=Moore CE, Wiatrak BJ, McClatchey KD, ''et al'' |title=High-risk human papillomavirus types and squamous cell carcinoma in patients with respiratory papillomas |journal=Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery |volume=120 |issue=5 |pages=698-705 |year=1999 |pmid=10229596 |doi=10.1053/hn.1999.v120.a91773}}</ref><ref name=Sinal_2005 />
 
==References==


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Latest revision as of 22:13, 29 July 2020

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Aysha Anwar, M.B.B.S[2],Seyedmahdi Pahlavani, M.D. [3]

Overview

Human papilloma virus is usually transmitted via the sexual route to the human host.[1] HPV life cycle is linked to epithelial differentiation and maturation of host keratinocytes, with transcription of specific gene products at every level.[2][3] The pathogenesis of HPV infection causing cancer is mainly linked to high risk types of HPV (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and 68). E6 and E7 protein products of HPV interact with two important cell cycle regulatory protiens, P53 and Rb proteins of host cell, causing unchecked cellular replication accumulating mutations leading to cancer.[4][5][6]

Pathophysiology

Transmission

  • Human papilloma virus is usually transmitted via the sexual route to the human host.[1]
  • Different types of HPV has a predilection for different types of epithelial tissue.[7]

HPV life cycle

  • HPV life cycle is linked to epithelial differentiation and maturation of host keratinocytes, with transcription of specific gene products at every level.[2][3][8]
  • HPV primarily infects basal cell layer of stratified squamous keratinised epithelium.[9]
  • Following transmission, the HPV uses the microabrasions to enter the basal stem cells via tissue specific heparan sulfate proteoglycans through clathrin-mediated endocytosis and/or caveolin-mediated endocytosis depending on the type of HPV.[10]
  • It than undergoes viral uncoating and viral DNA genome is than transported to nucleus maintaining a low copy number 10-200 viral genomes per cell (episome form).[11]
  • A sophisticated transcriptional cascade then occurs as the host keratinocyte begins to divide and become increasingly differentiated in the upper layers of the epithelium.
  • HPV uses host DNA replicative machinery to multiply as it lacks DNA polymerase activity.
  • Specific viral genes are transcribed at every level of keratinocyte differention.
  • Early proteins: E1, E2, E3, E4, E5, E6 and E7 proteins are synthesized primarily in middle layers, for reactivation of replication process in the differentiated cells.
  • Late proteins: L1, L2 proteins are transcribed in the most superficial layers for virion assesmbly, release and reinfection, as they code for capsid proteins.[12]


Genome organization of human papillomavirus type 16, one of the subtypes known to cause cervical cancer. (E1-E7 early genes, L1-L2 late genes: capsid)


Pathogenesis of HPV induced cancers

The pathogenesis of HPV infection causing cancer is mainly linked to high risk types of HPV (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and 68). Following HPV proteins play a significant role in the development of cancers associated with HPV.[13]

E6 and E7 proteins

E6 and E7 protein products of HPV interact with two important cell cycle regulatory protiens, P53 and Rb proteins of host cell, causing unchecked cellular replication accumulating mutations leading to cancer.[4]

  • Inhibition of P53
P53 protein is a cellular check point at G0/G1 to S phase of cell cycle and is also responsible for cell apoptosis for unrepaired DNA mutations. E6 protein binds P53 which results in degradation of P53, leaving cell without any check for mutations and unregulated cell.[5][14]
growth.[15][16][17][18][19]
  • Inhibition of Rb protein
Rb protein is negative regulator of cell growth. It binds E2F transcription factor which controls DNA replication and cyclin protein induced entering of cell into S phase of cell cycle. E7 protein binds Rb/E2F, releasing E2F from the inhibitory effect of Rb causing increased cyclin induced entry of cell into S phase of cell cycle, resulting in increased replication rate of cells accumulating mutations.[19][20][6][21]

HPV-Induced Diseases

Disease HPV type
Common warts 2, 7
Plantar warts 1, 2, 4
Flat cutaneous warts 3, 10
Anogenital warts 6, 11, 42, 43, 44, 55 and others
Genital malignancies 16, 18, 31, 33, 35, 39, 45, 51
Epidermodysplasia verruciformis more than 15 types
Focal epithelial hyperplasia (oral) 13, 32
Oral papillomas 6, 7, 11, 16, 32

References

  1. 1.0 1.1 Hernandez BY, Wilkens LR, Zhu X, Thompson P, McDuffie K, Shvetsov YB; et al. (2008). "Transmission of human papillomavirus in heterosexual couples". Emerg Infect Dis. 14 (6): 888–94. doi:10.3201/eid1406.070616. PMC 2600292. PMID 18507898.
  2. 2.0 2.1 Doorbar J (2005). "The papillomavirus life cycle". J Clin Virol. 32 Suppl 1: S7–15. doi:10.1016/j.jcv.2004.12.006. PMID 15753007.
  3. 3.0 3.1 Doorbar J, Quint W, Banks L, Bravo IG, Stoler M, Broker TR; et al. (2012). "The biology and life-cycle of human papillomaviruses". Vaccine. 30 Suppl 5: F55–70. doi:10.1016/j.vaccine.2012.06.083. PMID 23199966.
  4. 4.0 4.1 Moody CA, Laimins LA (2010). "Human papillomavirus oncoproteins: pathways to transformation". Nat Rev Cancer. 10 (8): 550–60. doi:10.1038/nrc2886. PMID 20592731.
  5. 5.0 5.1 Masuda H, Miller C, Koeffler HP, Battifora H, Cline MJ (1987). "Rearrangement of the p53 gene in human osteogenic sarcomas". Proc Natl Acad Sci U S A. 84 (21): 7716–9. PMC 299371. PMID 2823272.
  6. 6.0 6.1 Tommasino M, Adamczewski JP, Carlotti F, Barth CF, Manetti R, Contorni M; et al. (1993). "HPV16 E7 protein associates with the protein kinase p33CDK2 and cyclin A." Oncogene. 8 (1): 195–202. PMID 8380917.
  7. Rintala MA, Grénman SE, Puranen MH, Isolauri E, Ekblad U, Kero PO; et al. (2005). "Transmission of high-risk human papillomavirus (HPV) between parents and infant: a prospective study of HPV in families in Finland". J Clin Microbiol. 43 (1): 376–81. doi:10.1128/JCM.43.1.376-381.2005. PMC 540188. PMID 15634997.
  8. Doorbar J (2007). "Papillomavirus life cycle organization and biomarker selection". Dis Markers. 23 (4): 297–313. PMC 3851388. PMID 17627064.
  9. Kines RC, Thompson CD, Lowy DR, Schiller JT, Day PM (2009). "The initial steps leading to papillomavirus infection occur on the basement membrane prior to cell surface binding". Proc Natl Acad Sci U S A. 106 (48): 20458–63. doi:10.1073/pnas.0908502106. PMC 2787115. PMID 19920181.
  10. Johnson KM, Kines RC, Roberts JN, Lowy DR, Schiller JT, Day PM (2009). "Role of heparan sulfate in attachment to and infection of the murine female genital tract by human papillomavirus". J Virol. 83 (5): 2067–74. doi:10.1128/JVI.02190-08. PMC 2643729. PMID 19073722.
  11. Bedell MA, Hudson JB, Golub TR, Turyk ME, Hosken M, Wilbanks GD; et al. (1991). "Amplification of human papillomavirus genomes in vitro is dependent on epithelial differentiation". J Virol. 65 (5): 2254–60. PMC 240574. PMID 1850010.
  12. Yang R, Yutzy WH, Viscidi RP, Roden RB (2003). "Interaction of L2 with beta-actin directs intracellular transport of papillomavirus and infection". J Biol Chem. 278 (14): 12546–53. doi:10.1074/jbc.M208691200. PMID 12560332.
  13. de Sanjose S, Quint WG, Alemany L, Geraets DT, Klaustermeier JE, Lloveras B; et al. (2010). "Human papillomavirus genotype attribution in invasive cervical cancer: a retrospective cross-sectional worldwide study". Lancet Oncol. 11 (11): 1048–56. doi:10.1016/S1470-2045(10)70230-8. PMID 20952254.
  14. Hinds P, Finlay C, Levine AJ (1989). "Mutation is required to activate the p53 gene for cooperation with the ras oncogene and transformation". J Virol. 63 (2): 739–46. PMC 247745. PMID 2642977.
  15. Scheffner M, Huibregtse JM, Vierstra RD, Howley PM (1993). "The HPV-16 E6 and E6-AP complex functions as a ubiquitin-protein ligase in the ubiquitination of p53". Cell. 75 (3): 495–505. PMID 8221889.
  16. Havre PA, Yuan J, Hedrick L, Cho KR, Glazer PM (1995). "p53 inactivation by HPV16 E6 results in increased mutagenesis in human cells". Cancer Res. 55 (19): 4420–4. PMID 7671255.
  17. Werness BA, Levine AJ, Howley PM (1990). "Association of human papillomavirus types 16 and 18 E6 proteins with p53". Science. 248 (4951): 76–9. PMID 2157286.
  18. Magal SS, Jackman A, Pei XF, Schlegel R, Sherman L (1998). "Induction of apoptosis in human keratinocytes containing mutated p53 alleles and its inhibition by both the E6 and E7 oncoproteins". Int J Cancer. 75 (1): 96–104. PMID 9426696.
  19. 19.0 19.1 Demers GW, Foster SA, Halbert CL, Galloway DA (1994). "Growth arrest by induction of p53 in DNA damaged keratinocytes is bypassed by human papillomavirus 16 E7". Proc Natl Acad Sci U S A. 91 (10): 4382–6. PMC 43789. PMID 8183918.
  20. Pagano M, Dürst M, Joswig S, Draetta G, Jansen-Dürr P (1992). "Binding of the human E2F transcription factor to the retinoblastoma protein but not to cyclin A is abolished in HPV-16-immortalized cells". Oncogene. 7 (9): 1681–6. PMID 1323816.
  21. Brehm A, Nielsen SJ, Miska EA, McCance DJ, Reid JL, Bannister AJ; et al. (1999). "The E7 oncoprotein associates with Mi2 and histone deacetylase activity to promote cell growth". EMBO J. 18 (9): 2449–58. doi:10.1093/emboj/18.9.2449. PMC 1171327. PMID 10228159.

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