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Medical Microbiology

Medical Microbiology. Chapter 52 Papillomaviruses. Human Papillomaviruses. Human Papillomaviruses (HPVs) cause warts There are at least 100 different types of HPV Structure: Naked Icosahedral capsid Double-stranded DNA genome (circular w/ ~8000 base pairs) Only 9-10 genes!.

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Medical Microbiology

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  1. Medical Microbiology Chapter 52 Papillomaviruses

  2. Human Papillomaviruses • Human Papillomaviruses (HPVs) cause warts • There are at least 100 different types of HPV • Structure: • Naked • Icosahedral capsid • Double-stranded DNA genome (circular w/ ~8000 base pairs) • Only 9-10 genes!

  3. Human Papillomaviruses • Replication • HPV gains access to living cells through breaks in the skin • HPV genes promote cell growth (Why?) • This leads to viral DNA replication and transmission to new cells • It also leads to wart formation (it may take 3-4 months for the wart to appear) • Viruses are shed from the skin with dead cells • Skin Figure

  4. Human Papillomaviruses • Virus Survival • The virus expresses low levels of Ag • The skin is not easily accessible by immune cells - Figure

  5. Human Papillomaviruses • Viruses can be cleared by cell-mediated immunity, • Or the virus goes into latency and can recur • HPV have been implicated in the development of benign and malignant tumors • These viruses contain oncogenes which aid in the development of cancer • 85% of cervical carcinomas contain HVP DNA • 99.7% of people with cervical cancer have HVP antibodies • Pap smear is aimed at detection of cancerous or pre-cancerous cells (~5% of all pap smears contain HPV-infected cells)

  6. Human Papillomaviruses • Epidemiology • Fomite (floors, countertops, towels) • Direct spread (holding hands, STD) • HPV is probably the most common STD in the world • 20 million infected in US • 5.5 million new infections yearly?

  7. Human Papillomaviruses • Infections: • Skin warts on hands • Oral or respiratory warts • Genital warts (STD) • Treatment – cryotherapy probably the most common

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