Transcript History of HPV Detection - EvergreenStateCollege-Home

Virus Description
• Genus
Papovaviridae
• Morphology
– Naked, icosahedral
– 55 nm
– 72 capsomeres
– 2 capsid proteins
including 1 major (L1)
and 1 minor (L2)
– Circular, ds DNA, 8 Kb
Established as an
episome, but it can
integrate into the
host DNA
Discovery
• Human papillomas (warts) were linked to a virus in
1907
• Papillomavirus was first isolated in rabbits by
Richard Shope; thus the first oncogenic strain was
discovered
• No further studies were conducted until the 1970’s
• Once cervical cancer was linked to HPV, molecular
virology allowed these studies to move forth
• Papillomavirus is highly species specific
HPV Genome
E1 & E2: Early Viral Protein
Expression (Non-structural)
• E1 major protein
– Involved in
replication
– Exhibits helicase
activity
– Forms complex,
binds sequences at
the origin of
replication, and
recruits polymerases
and accessory
proteins to mediate
replication
• E2 regulatory protein
– For replication and
transcription from E6
promoter, as well as
DNA packaging
– Helps to recruit E1,
but also regulates
viral transcription
from early promoter
E4 & E5
• The functions of E4 & E5 are not fully
understood; however, they may be
involved in late viral functions
E6 & E7
• E6 & E7 interact with a many cellular proteins;
therefore, influencing the outcome of an
infection
• E7 is responsible for the formation of
papillomas
• E6 & E7 act as viral oncoproteins of high risk
HPVs, but they do not function as such in low
risk HPVs
L1& L2 Structural Proteins
• L1 (Major) and L2 (Minor) are structural
proteins that are assembled late and
spontaneously to form the icosahedral
capsids
• L1 (Major) makes up 80% of the viral
capsid
Normal Epidermis
HPV Replication &
Transcription in the Epidermis
• Infects basal cells of
dermal layer (low level
of transcription &
replication)
• DNA amplification and
capsid proteins made in
the upper spinous layer
• Transcription increases
in the spinous layer
• Squames released at
surface to release viral
particles
E6 & E7 Work Together as Viral
Oncoproteins to Immortalize target cells
• E6 binds to p53
tumor suppressor
via p100 (cellular
protein)
– Targets p53
leading to
degradation and
down-regulation
of pathways
involved in cycle
arrest and
apoptosis
• E7 binds to
retinoblastoma (RB)
tumor suppressor
– Represses
transcription of
genes involved
in apoptosis, as
well as interferes
with cell cycle
regulation
HPV DNA Map
Clinical Aspects of HPV
• There are approximately 138 HPV strains that have
been sequenced
• These include nongenital cutaneous, nongenital
mucosal types, and anogenital types (developing
around genital area or anal area)
• Cancerous types exist in all of these categories
• Low risk types HPV 6 & 11 are the most common
low risk genital types
• High risk types HPV 16 & 18 are the most common
high risk genital types
Genital Warts vs. Nongenital Warts
Genital warts
(sexually transmittled)
Condylomata acuminata
- Cauliflowerlike
Genital warts
-Smooth popular warts
Genital Flat warts
-Flat warts
Bowenoid Papules
-Small, elevated
Nongenital Warts
(non-sexually transmitted)
Common warts
- Hands, fingers and
knees
Plantar warts
-Feet
Flat warts
-Hands and face
Nongenital Mucosal Type
Nongenital Mucosal Disease
HPV Type
Respiratory papillomatosis
6, 11
Squamous cell carcinoma of the lung
6, 11, 16, 18
Laryngeal papilloma
6, 11, 30
Laryngeal carcinoma
16, 18
Maxillary sinus papilloma
57
Squamous cell carcinoma of the sinuses
16, 18
Conjunctival papillomas
6, 11
Conjunctival carcinoma
16
Oral focal epithelial hyperplasia (Heck disease)
13, 32
Oral carcinoma
16, 18
Oral leukoplakia
16, 18
Squamous cell carcinoma of the esophagus
16, 18
Nongenital Mucosal
Laryngeal papilloma
Conjunctival papillomas
Nongenital Types
Nongenital Cutaneous Disease
HPV Type
Common warts (verrucae vulgaris)
1, 2, 4, 26, 27, 29, 41, 57, 65
Plantar warts (myrmecias)
1, 2, 4, 63
Flat warts (verrucae plana)
3, 10, 27, 28, 38, 41, 49
Butcher's warts (common warts of people who handle meat,
poultry, and fish)
1, 2, 3, 4, 7, 10, 28
Mosaic warts
2, 27, 57
Ungual squamous cell carcinoma
16
Epidermodysplasia verruciformis (benign)
2, 3, 10, 12, 15, 19, 36, 46, 47, 50
Epidermodysplasia verruciformis (malignant or benign)
5, 8, 9, 10, 14, 17, 20, 21, 22, 23, 24, 25,
37, 38
Nonwarty skin lesions
37, 38
Common & Plantar Warts
Anogenital Types
Intermediate intraepithelial neoplasia
31, 33, 35, 42, 44, 45, 51, 52
High-grade intraepithelial neoplasia
16, 18, 56, 58
Carcinoma of vulva
6, 11, 16, 18
Carcinoma of vagina
16
Carcinoma of cervix
16, 18, 31
Carcinoma of anus
16, 31, 32, 33
Carcinoma in situ of penis (erythroplasia of Queyrat)
16
Carcinoma of penis
16, 18
Anogenital Types
Anogenital Disease
HPV Type
Condylomata acuminata
6, 11, 30, 42, 43, 44, 45, 51, 52, 54
Bowenoid papulosis
16, 18, 34, 39, 42, 45
Bowen disease
16, 18, 31, 34
Giant condylomata (Buschke-Löwenstein tumors)
6, 11
Unspecified intraepithelial neoplasia
30, 34, 39, 40, 53, 57, 59, 61, 62, 64, 66, 67, 68, 69
Low-grade intraepithelial neoplasia
6, 11, 43
Genital Warts
Infection
• Viral entry may result in a latent infection
or can develop within 1-3 months, or may
stay undetected for years
• Lesion likely due to clonal expansion of
infected cells
• Infection can be subclinical or clinical
Transmission
• HPV is released from the desquamating
superficial keratinocytes of the infected
stratified epithelia
• Transmission of cutaneous HPVs occurs
through direct contact with infected tissue or
through indirect contact with contaminated
objects and surfaces such as poolsides
• Transmission of genital HPV typically occurs
through sexual contact
HPV & Cervical Disease
• 99.7 % of cervical cancers
are a result of HPV-16 &
HPV-18
• HPV infection of the cervix
corresponds to low-grade
CIN (Cervical intraepithelial
Neoplasia)
– mostly flat aceto-whitening areas
including flat condyloma
Progressive Cervical Disease
• Starts as a benign noninvasive or squamous
intraepithelial lesion (SIL) or CIN
• Most low-grade intraepithelial lesions regress;
however, some remain unchanged
• 10-15% progress to moderate or severe
dysplasia; carcinoma in situ
• High grade CIN may develop into invasive
cancer after years or decades
– HPV 16, 18, and 45 are the most prevalent detected
Cervical Dysplasia
Detection Via Molecular Assays
Three molecular assays are used to detect HPV
in exfoliated cell samples or tissues
• Signal amplification assay
– Hybrid Capture 2 assay (only FDA approved assay)
• Target amplification assays
– PCR & in situ PCR
• Non-amplified hybridization assays
– Dot blot hybridization (DB), Southern transfer
hybridization (STH) and in situ hybridiation(ISH)
Normal Cells Progress to Dysplasia
http://www:pathology.washington.edu/clinical/HPV/
Moderate Dysplasia to Cancer
http://www:pathology.washington.edu/clinical/HPV/
Host Immune Response
• Most encounters of HPV are cleared by the host
between 1-2 years
• Strong immune response usually is not generated
• HPV can be a chronic infection
• Skin warts generate low levels of antibodies
• 50% of IgG found in HPV 6 & 11 genital types
• IgG and IgA humoral response to HPV 16 associated
CIN found in 50-75%
• Antibodies detected in 15-25% of those with no current
infection (most likely indicates past infection)
Host Immune Response
• Antibodies are rarely detected in patients with
pre-malignant cervical lesions
• Antibodies detected in 50% of women with latestage invasive HPV-16 associated with cervical
carcinoma
• Cell mediated immunity (CMI) is probably
extensively involved in control of the infection
– High incidence of cutaneous and anogenital
HPV associated disease is observed among
patients with genetic or aquired CMI
deficiencies
Host Immune Response
• Immunological and genetic aspects likely to
attribute to persistence and progression of
CIN
– Higher frequency found in HIV infected
women
• Functional alterations of LCs have been
shown to correspond with initiation and
progression of HPV related cervical disease
History of HPV Detection
• 1927
Georges Papanicalaou did research
on diagnostic cytology of the cervix
• 1940s
His research was published. First
Paps were in Korea
• 1950s
Paps began being used widely
• 1975
Harold zur Hausen linked HPV with
cervical cancer
• 1980s
His team isolated several genotypes
linked to cervical cancer and genital
warts
• 1999
PCR assay found HPV DNA in 99.7% of
cervical cancers studied
Genital HPV Types
• Only 40 types of HPV infect the genital tract
• Only these types can lead cause carcinoma:
– Types 16, 31, 33, 35, 52, 58
– Types 18, 39, 45, 70 (flat – in cervix, create tumors)
• Infections with certain “high-risk” HPV
types can progress to dysphasias or cancer
of the cervix, penis, anus, vagina and
tonsils.
• Only 1% of HPV infections will progress
to cervical cancer.
Prevalence of HPV
• HPV can show up in women on the cervix and
the vulva, inside the surrounding areas of the
vagina, and anus.
• It is common for HPV to exhibit no symptoms
• HPV can be acquired and cleared without the
person ever knowing that they were infected
• HPV is commonly passed unintentionally by
people who have no symptoms
• This is one reason why HPV is so common.
Most Women will be Infected
• HPV infection is estimated to involve 80% of
the sexually active population.
• As sexually active people you will probably
contract HPV at some point in your life.
• 3 of 4 Americans between the ages of 15 and 50
have been infected with HPV at some point.
• Your immune system will most likely clear it.
• HPV represents the most common sexually
transmitted viruses.
UW Students
• A UW study
found that
more than 60%
of college
women
became
infected over 5
years.
SOURCE: GRAPH ADAPTED
FROM R. L. WINER ET AL.,
AMERICAN JOURNAL OF
EPIDEMIOLOGY 157, 218 (2003)
HPV Persistence
• Most young women clear the virus, but it is
unknown how many completely clear it.
• Some HPV may go into remission after an active
period of months or years, but they are not
usually fully eliminated.
– “Active viral infections typically re-emerge from
latency during transient or permanent
immunodeficiency associated with sunburn,
pregnancy, physical and emotional stress, HIV
infection and cancer chemotherapy.” (WSDOH)
• There is no way to tell how long you have been
infected or when HPV will express.
Men and HPV
• Men also harbour and express HPV in the form
of penile, perennial and urethral papillomas.
• Men are much more likely to be carriers and not
develop cancer.
• A urethral swab for males to collect exfoliated
cells for Pap analysis exists but rarely practiced.
• There is not a FDA approved test for men.
• Clinically it is hard to get men in to get tested.
HPV Infection in the US
• An estimated 5.5 million people become infected
with various types of HPV each year in the U.S.
• An estimated 20 million people are currently
infected with at least one HPV type in the U.S.
• The “high risk” HPV associated cancers can take
years to develop, upwards
of 10 to 20 years.
• Cervical cancer affects
younger women more
frequently than most
other types of cancer.
Female Invasive Cancer Incidence
(Washington State 2001)
Source: WSDOH, Wash. Comp. Cancer Control, & American Cancer Society
Colorectal
10%
Lung and
Bronchus
13%
All others
42%
Cervix
2%
Breast
33%
Invasive Cervical Cancer Incidence & Death
C e rvic a l c a n c e r
Source: WSDOH, Wash. Comp. Cancer Control, & American Cancer Society
a g e -a d ju s te d ra te s p e r 1 0 0 ,0 0 0
10
9
8
7
6
5
216
cases
4
3
2
55
d e a th s
1
0
in c id e n c e
W a s h in g to n S ta te (2 0 0 1 )
m o rta lity
U S (2 0 0 0 )
Stage at Diagnosis (WA 2001)
Source: WSDOH, Wash. Comp. Cancer Control, & American Cancer Society
120
Number of cases
100
80
11 of 119
die
Total cases = 216
91%
survival
60
32 of 67
die
40
52%
survival
20
0
Local
Regional
17 %
survival
55%
survival
16 of 19
die
5 of 11 die
Distant
Unstaged
Stage at diagnosis
Risk Factors
• You do not have to have a lot of sex partners
to be exposed.
• History of multiple sex partners can increase
the number of other sexually transmitted
diseases
• Early age at first intercourse
• Smoking
• Diet
• NO Pap screenings
Pap Smears
• Invasive cervical cancer is
one of the most preventable
types of cancer due to the
effectiveness of the Pap test.
• Half of the women who develop
cervical cancer have not
had regular Pap tests.
Pap Smears
• The cytological changes associated with HPV
infection form the basis of the Papanicolau (Pap)
smear screening
• Sampling the cells from the cervix and examining
them for signs of malignancy
• The Pap diagnosis atypical squamous cells of
undetermined significance (ASCUS) during cervical
screenings
• This diagnosis indicates cell abnormality but is not
sufficient for a definitive diagnosis of a squamous
intraepithelial lesion
• Women who have these abnormalities are referred to
get a colposcopic biopsy
Treatments for “high risk” HPV
HPV is a long term virus; it is a chronic condition. Procedures
target the infected area; treatments do not get rid of the virus.
• Colposcopic Biopsy – diagnosis for the stage/grade of
HPV infection, high grade or low grade
• LEEP (loop electrocautery excision procedure) – cuts out
infected site, most common procedure.
• Laser – burns off infected site
• Cryosurgery – freezes off infected site
• General Surgery – hysterectomy, vulvectomy (in rare cases)
• Natural Products – stress, immune system boosters
Referral Guidelines for Women
with Abnormal Paps
% population in poverty
Poverty
Race/Ethnicity
Additional Risk Factors
• Women who avoid Pap smears
– Older women or church go'ers
– Self-proclaimed virgins and those who pledge
abstinence
• Truth about Abstinence:
– 88% of people who take abstinence pledges break them
within a year and a half.
– Those who pledge abstinence are 1/3 less likely to use
a condom when they become sexually active
– More likely to participate in risky sex acts
US compared to World statistics
United States
– 14,000 new cases of
cervical cancer are
diagnosed annually in
the U.S.
– In the U.S. 4,000 4,500 women die of
cervical cancer each
year
Worldwide
– 600,000 new cases of
invasive cervical
cancer diagnosed
annually worldwide.
– Cervical cancer kills
270,000 women
worldwide.
(2002 statistics)
Source: Science Magazine (2005). High Hopes and Dilemmas for Cervical Cancer Vaccine, Science Magazine, Volume 308, April
29, 2005.
Poorer Countries have > HPV Rates
SOURCE: GLOBOCAN 2002, IARC. Science Magazine, Vol. 308, Issue 5722, pages 618-621 , 29
April 2005
Vaccines on the Horizon…
SOURCE: Merck and GSK. Science Magazine, Vol. 308, Issue 5722, pages 618-621 , 29 April 2005
Challenges with the Vaccine
• Vaccine may have little impact on the cases of
cervical cancer
• Access to a provider and preventive
screenings/vaccines will still be an issue
• Poorer countries have a higher need for the
vaccine, but wealthier countries will get it 1st
Prevention
• Get regular Pap smears !
• Don’t smoke
• Avoid exposure to HPV – use a condom
• Advocate for greater access to preventive
screenings for all populations
• Live Healthy and Eat Healthy
Nutritional Support for HPV
• The following are suggested for protection, as well as
support for those who are infected
– Vitamin C
– Vitamin A & beta-carotene
– Folic acid
– Pyridoxine (B6)
– Selenium
– Zinc
Correlation has been found between Copper: Zinc
ratio (higher copper and lower zinc) in CIN and
cancer patients
Lactoferrin
Therapeutic Use of Lactoferrin
• Lactoferrin (LF)
– Iron binding glycoprotein is present in
many mucosal secretions including
saliva, tears, as well as vaginal and
seminal fluids
– Found in Human breast milk (HLF) as
well as bovine milk (BLF)
– Lf exhibits bacterialcidal and
fungicidal activity(particularly
Candida species) by depriving bacteria
and fungus from iron
Therapeutic Use of Lactoferrin
• Lf also exhibits anti-viral activity by inhibiting
viral binding to glycosamines such as heparin
sulphite; it is hypothesized that heparin
sulphite mediates the binding of HPV to the
host cell
• Studies have shown that BLF is a better
inhibitor than LF and it effectively inhibits
HPV-16