DNA Viruses

Question 1

where does DNA viral transcription and replication occur?

Answer 1

In the nucleus (except poxvirus)

Question 2

what enzymes transcribe and replicate genome?

Answer 2

Host RNA polymerase (except poxvirus) and either viral or host DNA polymerase for replication

Question 3

what dictates whether a virus uses viral or host DNA polymerase?

Answer 3

how large the virus is

Question 4

what is the order of replication, transcription and translation in the DNA viral life cycle?

Answer 4

transcription, translation then replication

Question 5

how is RNA polymerase recruited to transcribe viral DNA?

Answer 5

viral DNA has promotors that are regulated by both cellular and viral transcription factors (as long as the cell is permissive)

Question 6

in what cellular condition is viral DNA polymerase needed?

Answer 6

when cells are differentiated and nondividing

Question 7

what are two examples of viruses that use their own DNA polymerase?

Answer 7

herpesvirus and adenovirus

Question 8

why do DNA viruses have less random mutation than RNA viruses?

Answer 8

DNA polymerases have higher fidelity and proof reading. They are genetically more stable

Question 9

where is most genetic diversity created in DNA viral genomes?

Answer 9

in recombination within and beteen genomes

Question 10

what types of diseases does adenovirus cause?

Answer 10

respiratory (cold, pharyngoconjunctival fever, pneumonia), acute hemorrhagic cystitis, keratoconjunctivitis and gastroenteritis

Question 11

what is the transmission of adenovirus?

Answer 11

aerosol, fecal-oral, objects and poorly chlorinated swimming pools

Question 12

what are two particular susceptible populations to adenovirus?

Answer 12

children and military recruits

Question 13

what part of the virus facilitates adenovirus entry into the cell into the cytoplasm and how?

Answer 13

fibers (spikes) bind to cell receptors to cause endocytosis and acidification causes the spikes to lyse the vesicle

Question 14

where and how does the capsid of adenovirus uncoat?

Answer 14

it uncoats at nuclear pore by injecting it through (capsid docks at pore)

Question 15

what are the adenovirus gene expression phases?

Answer 15

immediate early (transcribing transcription factors), early (replication) and late (capsid proteins)

Question 16

does adenovirus use host or viral DNA pol?

Answer 16

viral

Question 17

where does adenovirus capsid assembly occur and how does it egress from the cell?

Answer 17

In the nucleus and it lyses out of the cell

Question 18

how is adenovirus diagnosed?

Answer 18

cell culture, antigen detection, PCR and serology

Question 19

when and how is adenovirus treated?

Answer 19

with immunocompromised patients in only most dire cases with cidofovir (nephrotoxic)

Question 20

is there a vaccine for adenovirus?

Answer 20

yes but it is only available to military personnel

Question 21

what is the most commonly diagnosed STD in the US?

Answer 21

HPV

Question 22

what epithelial diseases and malignancies are caused by HPV?

Answer 22

common warts, plantar warts and genital warts. head, neck, cervical and penile cancer

Question 23

what is the tropism of HPV?

Answer 23

differentiated epithelial cells

Question 24

what is the mechanism of wart formation associated with HPV?

Answer 24

HPV infects the precursor skin cells (stratum corneum) with little amplification. Once cells differentiate and become keratinized, the virus begins to replicate and cause hyperplasia

Question 25

why is it difficult to study HPV in culture?

Answer 25

transcription factors in late keratinocytes promote gene transcription

Question 26

what are the two possible courses of disease for a HPV wart?

Answer 26

it can be resolved by the host's immune system or it may transform into a tumor from viral transcription factors E6 and E7 (oncogenes)

Question 27

does HPV use host or viral polymerase?

Answer 27

Host

Question 28

why is it important to diagnose ant type genital HPV?

Answer 28

there are 13 high risk types of cancer causing HPV (type with DNA tests)

Question 29

how are HPV warts and malignancies treated?

Answer 29

cryotherapy, chemical ablation and colposcopy (excision in the cervix). ANy malignancies should be treated with oncotherapy

Question 30

what are the types of vaccines for HPV and what types are they active against?

Answer 30

gardasil: 6,11,16 and 18 cervarix: 16 and 18

Question 31

what is the vaccine to HPV comprised of?

Answer 31

VLPs: virus-like particles (empty capsids)

Question 32

how many speicies of herpesviruses are there and what is the average number that people are infected with?

Answer 32

8 and most people are infected with >3

Question 33

how long does a herpesvirus take to clear up?

Answer 33

it doesn't

Question 34

what is the host range and tropism of herpesvirus?

Answer 34

only infectious in humans and each virus prefers different cell types

Question 35

where does herpesvirus transcription take place?

Answer 35

in the host cell nucleus

Question 36

what phases of expression do herpesviruses have?

Answer 36

immediate early (transcription factors), early (replication of genome) and late (capsid proteins)

Question 37

how does herpesvirus replicate its DNA?

Answer 37

viral polymerase and accessory factors

Question 38

how does herpesvirus egress?

Answer 38

exocytosis

Question 39

what is the definition of herpesvirus latency?

Answer 39

genome is present in cell but infectious virions are absent

Question 40

what is a major barrier to vaccines with herpesviruses?

Answer 40

latency of the virus is established before it could be identified by the immune system and stays there for life

Question 41

herpesvirus is only contagious during active disease periods. True or false?

Answer 41

false. they are transmissable during periods of latency as well (asymptomatic shedding)

Question 42

how often do latent herpesviruses recur?

Answer 42

they may reoccur never or often

Question 43

how is HSV-1 transmitted?

Answer 43

close contact with active lesions or asymptomatic shedding

Question 44

what is the primary disease of HSV1 in childhood?

Answer 44

gingivostomatitis

Question 45

where are the primary lesions of HSV1 usually present and where is latency established?

Answer 45

above the waist (can be genital) and neurons

Question 46

what triggers and precedes recurrence of HSV1?

Answer 46

triggered by fever, sunlight or stress (etc) and it is preceded by a tingling, itching prodrome

Question 47

where are the lesions of HSV1 recurrence?

Answer 47

on lips or in mouth (may also be in eyes, on genitals or on fingers)

Question 48

what is often a complication of primary infection with HSV1 and 2?

Answer 48

meningitis (stiff neck and headache) | could also cause encephalitis

Question 49

what part of the brain is targeted by HSV1?

Answer 49

the temporal lobe

Question 50

how is HSV2 disease spread?

Answer 50

by close contact between mucous membranes (usually acquired during adulthood)

Question 51

what are the symptoms of primary HSV2 disease?

Answer 51

many lesions, pain, itching, fever and headache (not always but usually below the waist)

Question 52

where is latency established?

Answer 52

in neurons

Question 53

double infections with HSV1 and 2 are uncommon. True or False?

Answer 53

False. They are actually common

Question 54

what are the symptoms of recurrent HSV 2 disease?

Answer 54

prodoromic itching and tingling followed by vesicular lesions on labia, penis, anus, mouth etc.

Question 55

how is HSV diagnosed?

Answer 55

serology and PCR disinguish HSV 1 and 2 (differentiates risk for having children)

Question 56

when are antivirals used for HSV?

Answer 56

to shorten an infection, reduce transmission and as prophylaxis when people have frequent outbreaks

Question 57

what is the main antiviral used for HSV?

Answer 57

acyclovir

Question 58

how is HSV prevented?

Answer 58

safe sex, avoidance of cold sores, and chemoprophylaxis to reduce shedding

Question 59

are there any vaccines for HSV?

Answer 59

no

Question 60

what is the primary infection of VZV?

Answer 60

chicken pox- "dew drops on rose petals" rash

Question 61

how is Varicella transmitted?

Answer 61

aerosol (highly contagious)

Question 62

what are some complications of VZV primary infection

Answer 62

hepatitis, encephalitis, pneumonitis or bacterial infection of lesions

Question 63

what is recurrence of VZV and what latency is it caused by?

Answer 63

shingles (herpes zoster). caused by a latency in dorsal root ganglia

Question 64

who is most likely to develop shingles?

Answer 64

elderly and immunocompromised carriers of VZV

Question 65

where does outbreak of shingles occur?

Answer 65

along the skin surface of a single dermatome

Question 66

what are some complications of shingles?

Answer 66

bell's palsy, posterpetic neuralgia (indefinite pain) and retinitis (can cause infectious blindness)

Question 67

what is shingles infection of the eye called?

Answer 67

Herpes Zoster Opthalmicus

Question 68

what parts of the eye can be effected by zoster and what part can be destroyed?

Answer 68

all parts can be infected and it can destroy the retina

Question 69

how is VZV diagnosed?

Answer 69

clinical signs, PCR, antigen and serology

Question 70

how and when is VZV treated?

Answer 70

not required unless complicated. can be treated within 3 days of beginning of zoster symptoms to have relief. Treat with acyclovir and foscarnet (second line)

Question 71

how is VZV prevented?

Answer 71

two live, attenuated vaccines: varvax prevents varicella (1-50) zostavax prevents zoster (>50 yo)

Question 72

how is Epstein Barr Virus transmitted and what cells does it infect and become latent in?

Answer 72

it is transmitted in saliva and infects oral epithelial cells and B cells in tonsils. It remains latent in B cells

Question 73

what are the usual symptoms of childhood Epstein Barr Viruses?

Answer 73

they are usually asymptomatic

Question 74

when is EBV likely to recur?

Answer 74

during ties of imunosuppression (usually does not occur in healthy people)

Question 75

what complications are associated with latent EBV virus?

Answer 75

many different types of malignancies and oral hairy leukoplakia

Question 76

how is infectious EBV diagnosed?

Answer 76

clinical signs, serology and blood smear for elevated WBC and atypical lymphocytes

Question 77

how are EBV associated malignancies treated?

Answer 77

alleviate symptoms, treat immunosupression and treat with oncotherapy

Question 78

what antivirals and vaccines are available for EBV?

Answer 78

none

Question 79

how does CMV spread and what are its symptoms?

Answer 79

many different routs. symptoms may like mono but are highly dependent upon the host (most people are asymptomatic)

Question 80

how can CMV and EBV be differentiated clinically?

Answer 80

CMV has no sore throat but does have a rash

Question 81

what is the result of primary infection with CMV in pregnancy?

Answer 81

increased risk of congenital malformations. primary cause of deafness

Question 82

in which patients is CMV concerning?

Answer 82

pregnant women, AIDS patients and transplant recipients (frequent cause of transplant failure)

Question 83

how is CMV diagnosed?

Answer 83

serology, culture and PCR

Question 84

what antiviral drugs are used for CMV?

Answer 84

ganciclovir, foscarnet and cidofovir (last two nephrotoxic)

Question 85

what disease is caused by HHV6b and HHV7 and how is it transmitted?

Answer 85

roseola infantum, transmitted orally

Question 86

what are the symptoms of roseola and what age does it typically happen?

Answer 86

3 day high fever followed by faint rash. happens most at 7-13 months of age

Question 87

how is roseola treated?

Answer 87

supportive care for fever but resist giving antibiotics

Question 88

what must be ruled out when diagnising roseola infection?

Answer 88

drug allergy