Virology X Other Medically Important DNA Viruses

Question 1

1. Describe the major diseases or syndromes caused by the Human Papilloma virus (HPV).

Answer 1

HPV6, 11, 16, and 18 are associated with genital warts, HPV 16 and 18 are considered high risk for causing genital cancers

condylomas of the cervix or penis (macular or verucous) infection of the anus or fetus during birth;

warts (benign tumor or growth), Epidermodysplasia veruciformis (patients with unidentified immunodeficiency),

Question 2

1. Describe the major diseases or syndromes caused by the Molluscum Contagiosum Virus.

Answer 2

(of the pox family) causes a cluster of firm unbilicated papules on epithelial surfaces and genitals of adults (opportunistic in AIDS patients)

Question 3

1. Describe the major diseases or syndromes caused by the Parvovirus B19.

Answer 3

erythema infectiosum (5th disease or slapped cheek) mild rash in children

acute symmetric polyarthropathy in adults, erythropoiesis in people with hemolytic disorders, pure red cell aplasia and chronic anemia; hydrous fetalis (congenital anemia)

(note Aden-Assoicated Virus cannot reproduce without Adenovirus)

Question 4

2. Explain how HPV infection treated

Answer 4

non-genital warts can be left to resolve on their own; OTC topical preparations (Aldara), cryotherapy or podofilox/ INF-a directly injected, surgical removal or lazer removal

head and neck cancers associated with HPV are more responsive to radiation and chemotherapy than tobacco related cancers

advise patients that exposing skin with warts to UV light can lead to conversion to squamous cell carcinoma

Question 5

2. Explain how the virus that causes Molluscum Contagiosum is transmitted, how transmission can be prevented, how they are diagnosed and treated.

Answer 5

dx is based on appearance of lesion (cytopathic effect : Henderson-Paterson Cells)

transmitted by close contact and sexual activity, sugery, laser, freesing or electrodessication can be used

Question 6

2. Explain how Parvovirus is transmitted, how transmission can be prevented, how they are diagnosed and treated.

Answer 6

acute infection dx by IgM antigen capture assays (up to 3 mo); infection highest in late winter into spring, transmission is through respiratory secretions or close contact (rare); the virus is heat stable

usually mild and self-limited, tx of symptoms like NSAIDS for arthralgia or arthritis, blood transfusions for those with anemia; IV immunoglobin is available for immunocompromised

reduce transmission of respiratory secretion by hand washing and covering a cough, avoid kissing

Question 7

3. Explain the role of Papilloma viruses in cancer.

Answer 7

HPV can cause cancer of the uterine cervix, penis and anus; squamous cell carcinoma of the skin
head and neck cancers (specifically HPV16)

its important that all cancers require co-factor to cause mutagenesis in cells that have been immortalized by HPV

Question 8

4. Explain the nature of the HPV vaccine and its recommended use.

Answer 8

Gardisil is available for type 6, 11, 16 and 18 (80% infections); recommended for women and men between 9 and 26

Question 9

Describe the pathogenesis of HPV.

Answer 9

pathogenesis is closely tied to life cycle of virus and host cell

infection is initiated by infection of the basal epithelial cells, DNA enters the nucleus and remains an episome, at differentiation virus is activated; late T antigen protein causes cell proliferation accompanied by replication of the virus

virtually all cervical cancers contain integrated DNA and express E6 (p53) and E7 (Rb) which often interrupts E2 protein

Question 10

2. How are HPV infections diagnosed and treated?

Answer 10

veracious wart is often dx on appearance, genital warts are often dx on appearance also, sometimes with colposcopy
and acetowhite staining (PCR is available for genotyping)

Question 11

2. Explain how HPV transmission can be prevented.

Answer 11

HPVs are very stable in the environment and transmission can occur by close contact or by contaminated fomites (showers, lockers, etc.); infections must be initiated through a break in the skin; contaminated surfaces should be disinfected with bleach or acid

reducing the number of partners or delaying onset of sexual activate can reduce transmission (birth by cesarean if mothers are infected)

Question 12

List the notable varieties of human polyoma virus.

Answer 12

BK and JC virus are common, usually lead to asymptomatic infection but can be reactivated in immunocompromised states

BK virus kidney infection can result in graft failure, JC virus causes progressive multifocal leukoencephalopathy (PML)