HUMAN PAPILLOMA VIRUS HPV

1
HUMAN PAPILLOMA VIRUS(HPV)

• By
• Nathalia Cruz

2
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.
• Its classification is based on type of nucleic
  acid, strategy for replication, and morphology

3
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.

4
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.

5
HISTORY

• The papillomaviruses are part of the
  PAPOVAVIRIDAE family of DNA tumor viruses.
• First discovered in the early 40s.
• Gained notoriety in the early 80s when it was
  discovered that some types of HPV caused cervical
  cancer.

6
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.

7
APPEARANCE
8
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.

9
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.

10
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.

11
LIFE CYCLE
12
HPV TYPES

• 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 low-risk 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.

13
HPV GENOMIC ORGANIZATION

• 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 cis-regulatory elements.

14
HOW HPV CAUSES CANCER

• 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.

15
HPV TREATMENT

• Genital warts can be treated by a doctor and by
  different methods.
• Podofilox gel A patient-applied treatment for
  external genital warts.
• Imiquimod cream A patient-applied treatment.
• Chemical treatments (including trichloracetic
  acid and podophyllin), which must be applied by a
  trained health care provider to destroy warts.

• 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.

16
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.

17
SOURCES

• http//cinvestav.mx/genetica/MyFiles/Papillomaviru
  s/PAPepi.html
• http//www.life.umd.edu/classroom/bsci424/BSCI223W
  ebSiteFiles/LectureList.htmLectureList
• WWW.STDSERVICES.ON.NET/STD/WARTS
• http//www.ashastd.org/stdfaqs/hpv.html
• http//www.niaid.nih.gov/factsheets/stdhpv.htm