Flashcards in Other DNA viruses Deck (19):
HPV infections are often ______ and do cause latent infection
List two low risk and two high risk HPV strains
high risk: 16, 18
low risk: 6, 11
How does HPV transmission occur?
contact with fomites- shower floors, etc
requires a break in the epithelial barrier
Immunodeficient patients infected with HPV can develop ______________- warts appear as flat macular erythemetous spots. this can convert to sqamous cell carcinoma in UV light
In recent years, there as been an increase in ______ cancers caused by the genital HPV serotypes
head and neck
Infection with HPV is initiated when the virus infects ______ cells in the skin or mucous membranes
IN the basal cells, replication is not triggered- these cells serve as the latent site
as basal cells divide, the daughter cells move away from the basement membrane and trigger differentiation which activates virus to express early proteins
How does HPV infection cause a wart to form?
Expression of the early proteins can be detected in these cells and this includes the Large T antigen protein. Large T causes the cells to proliferate (see below) and as the cells divide, they push up the cells above them ultimately causing the wart to form.
--> virus triggers benign proliferation of epithelial cells at the site of infection. The infections remain above the basement membrane and so are somewhat invisible to the immune system
List some co-factors associated with a wart becoming cancerous
cigarettes, sunlight, X rays
Virtually all cervical cancers contain integrated viral DNA and express two proteins ___ and __
E6 and E7
integration disrupts E2, which is a negative regulator of E6 and E7
E7 interferes with retinobalstoma (regulates cell cycle)
E6 binds p53 (halts cell division)
Why do warts stain with acetowhite?
Because HPV infection alters keratin expression, the wart turns white and can be easily differentiated from the pink color of the normal mucosal surface.
What HPV strains are covered by Guardasil?
6, 11, 16, 18
How is molluscum contagiousum transmitted?
close contact, sexual activity
_______ is the only pox virus circulating in humans
molluscum contagiosum virus
What are common manifestations of molluscum contagiousum virus?
cluster of firm umbilicated papules on the skin and genitals
immunocompromised: can persist, become larger
______ is a parvovirus that is non pathogenic and has no associated diseases. It establishes latent infection by integrating into a specific site on chromosome 19. It cannot replicate without a co-infection with adenovirus
_____ is the only pathogenic parvovirus in humans
How is parvovirus B19 spread
respiratory secretions, higher rates in winter, spring, early summer
What diseases are caused by parvovirus B19?
erythema infectiosum/ fifth disease/ slapped cheek disease
immunocompromised/ hemolsys: aplastic crisis