HPV Flashcards
What method is used to distinguish between the different strains of HPV?
• what is the utility in this method?
60 strains determined by genotype not serotype
• Genotype determines: Morphology, Site, Oncogenic potential of virus
Differentiate between Permissive and non-permissive cells in HPV infection?
• which are likely to allow for onchogenesis?
Oncogenic Potential Depends on Permissive vs. Non-permissive Cells:
• Permissive: allow for lytic replication, virus never inserts into the genome
• Non-permissive: Genome is replicated but no virus is produced because late genes (aka structural genes) needed to leave the cell are not expressed. These cells allow for oncogenic change.
What cell types get infected by HPV?
Places that get infected: Mucosal and Epidermal cells
What is the normal Non-onchogenic mechanism by which HPV persists in the epidermis?
- *Normal Pathogenesis = no integration into host**
1. Non-permissive basal cells get infected with HPV that does NOT insert into the human chromosome but the circular viral chromosome IS maintained in these cells WITH low levels of viral genome replication and NO virion production.
- As cells move up from the basal layer toward stratum coreum episomal replication takes place at increased frequency
3. Cells become permissive on their way up and LYTIC CYCLE occurs and infection is re-seeded
What MAJOR difference is there in pathogenesis for a virus that is becomes oncogenic versus one that does not?
- *Oncogenesis = Integration into HOST chromosome**
1. E2 regulatory gene gets damage on while integrating into host chromosome
2. E6 and E7 genes become dysregulated
- E6 causes P53 degradation, E7 causes Rb inactivation
- Loss of cell cycle control in human cells
What Tumor Suppressor Gene is suppressed by E6?
P53
What tumor suppressor gene is acted on by E7?
E7 prevents Rb form working
What strains is the HPV vaccine protective against?
• what is in the vaccine?
HPV vaccine:
•Protective against: HPV 6, 11, 16, 18
• Uses L1 capside protein to self assemble into pseudocapsids
**So the vaccine protects against the types that cause anogenital warts, Sub-clinical papilloma virus infection, Infantile laryngeal papillomas, and head and neck cancers***
What HPV genotypes are associated with:
• Angogenital Warts
• Sub-clinical papilloma infection
**Are these vaccine protected?
• Angogenital Warts - 6 and 11
• Sub-clinical papilloma virus infection - 16 and 18
Yes, these 4 types are covered by gardasil
What HPV genotypes are associated with:
• Infantile Laryngeal Papillomas
• Head and Neck Cancers
Infantile Laryngeal Papillomas - 6 and 11 (anogenital strains that are contracted while coming through the birth canal)
Head and Neck Cancers - 16 and 18 (from oral sex with sub-clinical papilloma virus infection)
Who gets Epidermodysplasia verruciformis?
People with T cell deficiencies
How is a diagnosis of HPV made?
- Clinical Appearance
- Genotyping on inconclusive Pap smears in women over 30
**HPV cannot be cultured**
Why are things like Imiquimod useful in treating HPV warts?
It can activate the immune system to recognize the HPV antigens on your cells. Typically HPV illicits only a weak immune response
Who should get the HPV vaccine?
All boys and girls 11-26
HPV
• Structure and Genome type
Papovaviridae (Subfamilies: Papilloma, Polyoma, Vacuolating virus SV40)
Structure
Circular dsDNA genome (5-8 kbp) VERY SMALL, NONENVELOPED icosahedral capsid
Replication Cycle
***So small that they don’t even encode their own RNA dependent DNA pols.***
HPV
• What bigger family is this virus a part of?
Papovaviridae (Subfamilies: Papilloma, Polyoma, Vacuolating virus SV40)
Structure
Circular dsDNA genome (5-8 kbp) VERY SMALL, NONENVELOPED icosahedral capsid
Replication Cycle
***So small that they don’t even encode their own RNA dependent DNA pols.***
