Transcript HUMAN PAPILLOMA VIRUS (HPV) By: Nathalia Cruz What is a Virus? ► Exceptionally simple living microbes. ► Contain a single type of nucleic acid (DNA or RNA)

HUMAN PAPILLOMA VIRUS
(HPV)
By:
Nathalia Cruz
What is a Virus?
► Exceptionally
simple living microbes.
► Contain a single type of nucleic acid (DNA
or RNA) and a protein coat.
► Obligatory intracellular parasites.
► Range from 20 to 14.000 nm in length.
► It’s classification is based on type of nucleic
acid, strategy for replication, and
morphology
HUMAN PAPILLOMA VIRUS
► HPV
is the virus that causes warts.
► More than 100 different kinds, 30-some of
this cause genital HPV.
► Spread by sexual contact or from mother to
baby.
► Genital warts appear 6 weeks to 8 months
after contact with an HPV infected person.
HPV
► The
most common sexually transmitted
disease worldwide.
► Certain types of HPV are linked with cervical
cancer.
► Divided into 2 subcategories: Genital Warts
and Cervical Dysplasia.
► Most people do not know they have it.
► There are high risk and low risk types of it.
HISTORY
► The
papillomaviruses are part of the
PAPOVAVIRIDAE family of DNA tumor
viruses.
► First discovered in the early 40’s.
► Gained notoriety in the early 80’s when it
was discovered that some types of HPV
caused cervical cancer.
MORPHOLOGY
► Papilloma
virus genome is circular covalently
closed double stranded DNA of about 8 kbp.
► All PV genes are coded in one of the 2 DNA
strands utilizing the alternative splicing for
the individual expression of each gene.
► Papillomavirus expression is characterized
by a large array of mRNAs cells coding for
different genes.
► 55 nm in diameter.
APPEARANCE
MECHANISM OF INFECTION
► All
PV exhibit extreme specificity for
infection on epithelial cells.
► The papillomavirus epitheliotrophy resides in
the interaction of specific transmission
factors with the viral regulatory region LCR.
► The infection normally results in
hyperproliferation of the host cell and may
lead to transformation and immortalization.
GENITAL WARTS
► Sometimes
called condylomata acuminata.
► Are soft, moist or flesh colored, and appear
in the genital area within weeks or months
after infection.
► Sometimes appear in clusters and are either
raised or flat, small or large.
► Women: appear in the vulva, cervix, vagina
and anus.
► Men: Can appear on the scrotum or penis.
LIFE CYCLE (HPV-16)
► Starts
with the infection of the host cell.
► The virus DNA is released within the nucleus
► Numerous cellular transcription factors interact
with the non-coding viral regulatory region (LCR),
starting transcription of the two hpv-16
transforming early genes (E6 and E7).
► The transforming proteins interact with the cellular
antioncogenic regulator p53 disrupting the cell
cycle.
LIFE CYCLE
HPV TYPES
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Numbered in order of discovery.
30 HPV types primarily infect the squamous epithelium of
the lower anogenital tracts of both males and females.
HPV types 6, 11, 42, 43, or 44 present as papillary
condylomas, may also present as flat lesions that may or
may not be visible to the unaided eye are part of the “lowrisk” HPV types.
Types 16, 18, 31, 33, 35, 45, 51, 52, and 56 are
considered “high-risk” types because they have been found
in cervical and other lower genital tract cancers.
HPV GENOMIC ORGANIZATION
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Three main regions (early,
late and the long control
region)
(E) resides the
transformation and
immortalization potential.
(L) Two capsid genes.
(LCR) contains all the cisregulatory elements.
HOW HPV CAUSES CANCER
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HPV DNA integrates into the host genome.
The proteins E6 and E7 are produced from the resultant DNA.
E6 binds and degrades p53 (a tumor suppressor gene).
If the DNA is altered, the cell keeps replicating. The mutation rate of
the cell increases.
E7 binds and degrades retinoblastoma (another tumor suppressor
gene).
Retinoblastoma normally keeps the cell from growing too fast or
responding to growth stimulators. This inhibitory factor is now lost.
without these two mechanisms to slow down cell growth and prevent
mutation. . .
Malignant Transformation Occurs.
HPV TREATMENT
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Genital warts can be treated by
a doctor and by different
methods.
Podofilox gel: A patientapplied treatment for external
genital warts.
Imiquimod cream: A patientapplied treatment.
Chemical treatments (including
trichloracetic acid and
podophyllin), which must be
applied by a trained health care
provider to destroy warts.
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Cryotherapy: Uses liquid
nitrogen to freeze off the warts.
Laser therapy: Uses a laser
beam or intense lights to
destroy the warts.
Electrosurgery: Uses and
electric current to burn off the
warts.
Surgery: Can cut away the
wart in one office visit .
Interferon: an antiviral drug,
which can be injected directly
into warts.
CURE
► There
is currently no cure for human
papillomavirus.
► Once an individual is infected, he or she
carries the virus for life even if genital warts
are removed.
► The development of a vaccine against HPV
is under way, but is still not available.
► If left untreated, some genital warts may
regress on their own.
SOURCES
► http://cinvestav.mx/genetica/MyFiles/Papillo
mavirus/PAPepi.html
► http://www.life.umd.edu/classroom/bsci424
/BSCI223WebSiteFiles/LectureList.htm#Lect
ureList
► WWW.STDSERVICES.ON.NET/STD/WARTS
► http://www.ashastd.org/stdfaqs/hpv.html
► http://www.niaid.nih.gov/factsheets/stdhpv.
htm