Microbio Week 11 - DNA viruses (Exam 3) Flashcards
How do papillomaviruses replicate?
By entering the cell cycle
(they don’t have viral DNA polymerase!)
T/F: A small number of papillomavirus serotypes exist
FALSE, a LARGE number of papillomavirus serotypes exist
What are the 2 main types of HPV?
Mucosal
Cutaneous
Is HPV a localized or generalized/systemic infection?
Localized
(only on skin or mucosal surface)
Does HPV have a viremic stage?
NO
What does cutaneous HPV form on the skin that can persist and spread?
Benign warts
Can benign warts from cutaneous HPV be cleared without treatment?
Yes
Where can cutaneous warts spread through autoinoculation?
To oral or genital mucosa
What is the most common STD in the US?
Anogenital warts
What are the most common types of mucosal HPV? Are they low or high risk?
HPV 6 and 11 - low risk
HPV 16 and 18 - high risk
What are HPV 6 and 11 associated with?
90% of genital warts
What are HPV 16 and 18 associated with?
70% of anogenital cancers
Most cervical cancers
What else can HPV 6 and 11 cause?
Recurrent respiratory papillomatitis
How do children acquire oral HPV?
At birth from mother
How do adults acquire oral HPV?
Oral sex
Where can mucosal HPV warts be found? What is required if this occurs?
Larynx - requires surgical removal
What is needed so the HPV virus can infect the basal cell layer?
Break in the skin/mucosa
In HPV, the basal cell will then replicate to repair the wound, and the virus will establish several copies of itself in an _________ form
episomal
As the HPV virus containing cell moves through the different epithelial layers, what will it express?
Different viral proteins
In the upper epithelial layers, the HPV virus will prod the terminally differentiated cell to replicate so it can make thousands of copies of ________ ______ and lots of ____________ ____________.
It does this by the viral _____ protein binding and inactivating the cellular Rb protein, which causes the cell to go into the cell cycle
viral DNA; capsid protein; E7
What is HPV cancer caused by?
Dysregulation of E6 and E7 genes of HPV
How do E6 and E7 genes of HPV become dysregulated?
By integrating viral DNA episome into basal cells’ DNA
Is genome integration a normal part of HPV’s replication?
NO
What does the integration of viral HPV episome turn off? What does this lead to?
Turns off a viral protein that controls E6 and E7 levels -> leads to high levels of E6 and E7 in basal cells
In the oncogenic forms of HPV, which protein will bind and degrade the Rb protein causing the cell to go into the cell cycle?
E7
In oncogenic forms of HPV, which protein will cause the degradation of p53, allowing the cell to continue to cycle and accumulate mutations?
E6
In most cases, HPV infections spontaneously ___________ (meaning they are cleared by the immune system).
regress
When do problems with HPV infection occur?
If the infection is persistent and the patient is high risk
(can result in cancer)
T/F: Once the immune system is activated, most people are protected from reinfection from that strain of HPV. Some people might have cross-protection between different strains of HPV.
True
Is it possible to be infected with more than one strain of HPV, either simultaneously or sequentially?
Yes!
HPV is known to contribute to 6 different cancers. Name them
Cervical
Anal
Vulvar
Vaginal
Penile
Oropharyngeal
There are now more HPV __________ cancers per year than cervical cancers
oropharyngeal
Which stain of HPV causes almost all oropharyngeal cancers?
HPV 16
What can increase risk of cancer from HPV infection?
Smoking and drinking
As the number of people smoking reduced, oropharyngeal cancers ___________
decreased
_________ cancer cases have been on the rise, with more being caused by HPV in younger _______________
Oral; non-smokers
What type of vaccine is the HPV vaccine?
Subunit
What does the subunit vaccine for HPV have in it?
One coat protein of HPV
It is recommended that girls and boys ages ________ get vaccinated with _____ doses of the HPV vaccine
9-14; 2
How many doses of the HPV vaccine must be done after age 14?
3
What age group seems to have the most durable response to the HPV vaccine?
9-14
Describe the polyomavirus
dsDNA
Circular
Naked
Icosahedral
Do polyomaviruses have a viral DNA polymerase?
NO
What is needed for polyomaviruses to replicate their viral DNA?
Cell must divide
T/F: JC only causes problems in the immunocompromised
True
Name the 4 types of patients JC causes problems in
AIDS
Transplant recipients
People taking immunosuppressive drugs
Hematologic malignancies
What is JC caused by?
Polyomavirus
T/F: All of polyomaviruses are very common; most people have been exposed or are latent/chronically infected
True
A large majority of people have been infected with the JC virus by adulthood. Many people are latently infected and sporadically shed virus in their __________
urine
The problems with JC arise when the virus mutates and becomes _________, and the person is immunosuppressed
neurotropic
What cells does the mutant JC virus infect and kill, causing CNS demyelination and Progressive Multifocal Leukoencephalopathy (PML)
Oligodendrocytes
Before ART, ______ occurred in people living with AIDS. However, it can still occur in people with AIDS and other immunosuppressed people.
PML
What is the treatment for JC virus induced PML?
Stop the immunosuppressive agent
Start HIV therapy to make immune system more active
T/F: There is not lasting damage from PML
FALSE, there is lasting damage from PML
Describe parvovirus
ssDNA
Linear
Naked
Icosahedral
Does parvovirus have DNA polymerase?
NO
Can parvovirus stimulate the cell to grow, like polyomavirus or papillomavirus?
NO
How does parvovirus replicate?
Infects actively dividing cells
What does parvovirus B19 cause?
Erythema infectiosum-fifth disease
Is Erythema infectiosum-fifth disease a localized or generalized infection?
Generalized
The “slapped cheek rash” characterizes which infections?
B19
In B19 infections, the _______ develops because of the immune response and the person is no longer contagious
rash
The B19 parvovirus needs to infect actively dividing cells and preferentially infects ________
precursor cells, killing those cells.
What does this cause?
erythroid; causes transient anemia
For people who already have an increase in RBC turnover due to hemoglobin disorders like sickle cell or chemotherapy, what can a B19 infection cause?
Transient aplastic crisis -> causing severe drop in RBCs
If infected with parvovirus B19 in the 1st trimester, what is there a chance of?
Miscarriage
If infected with parvovirus B19 anytime during pregnancy, what is there a chance of causing?
Hydrops fetalis
Describe poxvirus
dsDNA
Linear
Enveloped
Where do poxviruses replicate?
Cytoplasm
What do poxviruses bring into the cell so it can make mRNA and not have to enter the nucleus?
DNA-dependent RNA polymerase
Name the poxviruses
Molluscum virus
Orthopoxviruses (variola, cowpox, mpox, vaccinia)
What virus causes raised lesions of the skin that appear smooth with a dimple in the middle and are actively secreting the virus?
Molluscum virus
Is molluscum contagiosum a local or generalized infection?
Local
How is molluscum contagiosum spread?
Close contact
Autoinoculation
T/F: The molluscum contagiosum infection usually disappears without intervention by 2 to 12 months without scarring and affects children more than adults
True
Orthopoxviruses (Variola, Cowpox, Mpox, Vaccinia)
