HPV

Question 1

What type of virus is HPV? What are the characteristics of HPV?

Answer 1

circular, double stranded DNA virus, naked (no envelope), icosahedral capsid, inserts into the host genome

Question 2

How many strains of HPV are there? Which strains of HPV cause clinical manifestations?

Answer 2

about 140 strains (a lot!). The main strains that cause HPV are
6 and 11 - genital warts (condyloma accuminatum)
16 and 18 - cervical and anal cancer

Question 3

Which HPV proteins are responsible for the its ability to cause cancer? What do they inhibit?

Answer 3

E6 and E7 are the oncogenic proteins of HPV
E6 inhibits p53, a tumor supressor gene
E7 inhibits pRB (retinoblastoma protein), a cell cycle regulator

Question 4

What is a characteristic cytology finding on Pap smear for HPV?

Answer 4

koilocytes (nuclear enlargement, hyperchromasia, perinuclear halo, irregular nuclear membrane)

Question 5

What are the vaccines for HPV?

Answer 5

The antigen is an empty shell of the normal virus. It self assembles but is not infectious.

Bivalent vaccine - strains 16 and 18 called cervarix, given to girls age 9-26
Tetravalent vaccine - strains 6, 11, 16, 18 called gardasil, given to girls age 9-26, boys 11-21, MSM, immunocompromised