Major DNA viruses Flashcards Preview

CMBM exam 3 > Major DNA viruses > Flashcards

Flashcards in Major DNA viruses Deck (103):
1

Molluscum Contagiosum

Poxviridae

2

B19

only human parvovirus
ss, linear DNA, naked icosahedral
causes Fifth's disease - slapped cheek rash
Trans: respiratory and oral secretion

3

What sort of cells does B19 preferentially infect?

mitotically active erythroid precursor cells in the bone marrow
infects proerthyroblast

4

Describe the lytic phase of B19

viremia is established
viral shedding, moves out of bone marrow
flu like symptoms

5

Describe the non infections immune response of B19

circulating immune complexes that cannot fix complement results in erythematous, maculopapular rash, arthralgia, arthritis (last two rare)

6

What is important for clearing B19?

IgG

7

what causes common rash illness in school aged children?

B19

8

lacy reticular maculopapular rash on trunk and extremities

B19

9

Rash appears with IgM

B19

10

what is the concern with a B19 infection in a sickle cell patient?

Aplastic crisis - drop in RBCs

11

concerns with Intrauterine infection of B19

hydrops fetalis or fetal death

12

Rash appears with IgM

B19

13

How would you treat acute vs. chronic B19?

since mild - acute treat with supportive care, ibuprofen for fever and topical anesthetic or antihistamine
For chronic which can be seen in IC pts - IV immunoglobins

14

Adenovirus

DsDNA - linear
non enveloped
respiratory trans. via inhalation of droplets or eye contact
GI trans. - fecal-oral route

15

Pathogenesis of Adenovirus

typically infects where comes in contact with mucoepithelium
commonly infects local lymphoid tissue - conjunctiva, adenoids, tonsils, respiratory, peyer's patches
*typically not pathogenic

16

Where can Adenovirus persist?

in tonsils and adenoids in childern
in intestines in adults

17

How does Adenovirus interfere with host defenses?

interferes by blocking IFN and T cells

18

Viral oncogenes of Adenovirus

lytic in nature so tumorgenesis is not concern
late proteins E1A and E1B leads to cell growth
E1A inactivates pRB (retinoblasts)
E1B inactivates p53 (mediates cell apoptosis)

19

What are some clinical manifestations of Adenovirus

Acute febrile pharyngitis
Pharyngoconjunctival fever
Acute respiratory disease
cold, laryngitis, croup, bronchiolitis, viral pneumonia
"shipyard eye" -epidemic keratoconjunctivitis
cervicitis and urethritis - rare in women
acute gastroenteritis in infants

20

With Adenovirus infections in childern, what symptoms would you see in infants and young children versus older children?

infants and young - acute febrile - stuffy nose, fever, sore throat
Older children - Pharyngoconjunctival fever - tends to occur in outbreaks. associated with underchlorinated pools

21

Notice lots of military recruits have Acute respiratory disease. Symptoms include fever, runny nose, cough and pharyngitis. A couple of infected recruits also present with conjunctivitis. What could it be?

Adenovirus

22

papillomaviridae

HPV
small, circular (so has own polymerase to make DNA but use host polymerase for RNA), in nucleus, ds, non enveloped

23

Papilloma

benign
squamous epithelial growth
wart
verruca

24

HPV encodes proteins that promote

cell growth
lytic infections in permissive cells
transforming, oncogenic infection in non permissive cells

25

What does HPV cause?

warts, condylomas, papillomas and cervical carcinomas

26

How long could HPV incubate?

2 weeks to 1 year

27

what strains of HPV could cause Anogenital warts?

6 and 11

28

what strains of HPV could cause Cervical carcinomaL?

16 and 18

29

HPV protein E1

binds DNA at ori and promotes viral DNA replication and has helicase activity

30

HPV protein E2

binds DNA
helps E1
and activates viral mRNA synthesis

31

HPV protein E5

oncoprotein that activates the EGF receptor to promote growth

32

HPV protein E4

disrupts cytokeratins to promote release

33

E6 and E7 of HPV 16 or 18

become immortilizing genes
E6 binds to p53, activates telomerase and suppresses apoptosis
E7 binds p105RB

34

L1 and L2 of HPV

late structural (capsid) proteins

35

describe the development of papilloma

infects basal cells of dermal layer via L1 VAP/ integrins
replicates in squamous epithelium of skin(warts) or mucus membranes (genital, oral or conjunctival) -> epithelial proliferation

36

what is a wart ?

virus stimulation of cell growth leads to thickening of basal and prickle layers
epithelial spikes form - papillomatosis
Koilocytes

37

Koilocytes

enlarged keratinocytes with haloes around shrunken nuclei develop

38

Where is the HPV produced in skin layers?

in granular cells near the final keratin layer
not a lytic infection
shed from surface of epithelium

39

Common warts - HPV

benign self limited proliferative lesions

40

Benign head and neck tumors - HPV

usually solitary and rarely reoccur after excision
laryngeal papilloma most common type
causes most common tumor of the oral cavity

41

Anogenital Warts - HPV

condylomata acuminata occur mostly on squamous epithelium of external genitalia/perineum

42

Cervical dysplasia and Neoplasia - HPV

common STD
asymptomatic, may cause slight itching
appear as soft, flesh colored wart that are flat, raised or cauliflower shaped

43

Describe the progression of HPV medicated cervical carcinoma

infects and replicates in the epithelial cells
matures and is released as cells progress through terminal differentiation
in some cells, circular genome integrates into host chromosomes inactivating the E2 gene
expression of other genes stimulates the growth of the cell and possible progression to neoplasia

44

What laboratory tests can test for Cervical dysplasia caused by HPV?

cytology: koilocytotic cells (vacoulated cytoplasm)
Wart: microscopically view hyperplasia
Papanicolaou stain of exfoliated cervicovaginal squamous epithelial cells
DNA probe anaylsis or PCR (best method)

45

How do you treat HPV?

cryotherapy, electrocautery
inteferon, imiquimod or stripping with duct tape to stimulate immune response

46

What sort of vaccinations are available for HPV?

Gardasil - Tetravalent (HPV-6, 11, 16, 18)
Cervarix - divalent (HPV 16 and 18)
For girls, boys and women 9-26 years
three doses: initial, 2 month booster, 6 month booster

47

Herpesviruses
"Herpes is forever!"

HSV, VZV
Large, ds, enveloped linear

48

What is characteristic of a Herpes infection?

lytic, persistent, latent and immortalizing

49

Describe the alpha-herpesvirinae (HSV group)

rapid cytolytic growth cycle
commonly destroy the host cell
latent in neuronal ganglia
HSV1 HSV2 VZV

50

Beta-herpesvirinae (CMV group)

slow replication
latency non neuronal 1* lymphoreticular cells
CMV HHV6 HHV7
transmitted through saliva
Roseola rash seen on neck, trunk and thighs

51

Gamma-herpesvirinae (lymphoproliferative group)

replicate in mucosal epithelia
immortalized in host lymphoid cells
latency established in mucosal epithelia
EBV HHV8
transmitted through saliva and semen
in IC pts, can become opportunistic and cause cancer

52

What is the clinical presentation of HSV1

lesion on the oropharynx, cold sores, fever blisters
aquired in early childhood

53

What is the clinical presentation of HSV2

lesions on genitalia
2/3 spread from asymptomatic partners

54

Clinical presentation of HSV 1 and 2

vesicular lesions and shallow ulcers accompanied by fever, myalgia and malaise

55

What is occuring in the initial stage of HSV infections ?

virus replicates at high rates
infection resolves - within two weeks
virus travels axonally to sensory nerve ganglion and produces acute infection at ganglion
leaves episomal (circular) DNA

56

what occurs during HSV reactivation ?

stimuli causes the viral episomal DNA to produce LAT which causes the viral DNA to linearize again and to begin producing virus

57

What is the primary manifestion of HSV-1 in children?

Gingivostomatitis
primary infx of upper body
fever, malaise, lesions last 3 weeks

58

What is the primary manifestion of HSV-1 in adults?

Pharyngitis or tonsillitis
1 week duration

59

What can trigger reactivation of HSV?

stress, UV light, infection, menstruation, decreased immunity

60

What can suppress reactivation of HSV?

strong cellular immune response
high antibody titer doesnt prevent

61

What are the secondary/recurrent manifestations of HSV?

cold sore
keratoconjunctivitis (HSV 1 of the eye) - 2nd MCC of corneal blindness, corneal scarring
Herpetic gladiatorium - wrestlers and burn victims
Herpetic Whitlow - fingers and hands - chiropractors

62

What are the differences in clinical manifestations between HSV 1 and 2?

HSV 1 - Keratoconjunctivitis, Gingivostomatitis, tonsilitis, labialis, esophagitis, tracheobronchitis, gladiatorum
HSV 2 - meningitis, perianal, neonatal HSV
both - encephalitis, oral, genital, whitlow

63

Complication of HSV1

Encephalitis

64

What is a manifestation of Congenital/perinatal transmission of HSV?

CNS (49%), skin, eyes and oral cavity (50%)
asymptomatic

65

Complication of HSV2

Meningitis
mostly benign and self limiting with no neurologic

66

Complication of HSV in Immune suppressed pts

pneumonia
severe mucocutaneous lesions

67

How would diagnosis of HSV 1/2 be done?

clinical appearance
virus isolation from lesions
PCR of CSF for HSV encephalitis
Valacyclovir, acyclovir, famciclovir

68

How is Varicella Zoster virus transmitted?

acquired by respiratory droplet inhalation of close contact

69

What are some characteristics of the VZV infections in children and adults?

highly contagious, 90% of cases less than 9 years old
97% of adults are seropositive
more severe if primary infection occurs in adults

70

Reactivation of VZV results in ?

Shingles/Zoster
triggered by increased age and/or decreased immunity

71

What are complications of VZV?

superimposed bacterial infections
Pneumonia

72

what is the clinical presentation of the primary infection of VZV?

chicken pox
fever, irritability and lymphadenopathy

73

What is the clincal presentation of a reactivation of VZV?

early symptoms: acute pain and redness of dermatome followed by rash
Post herpetic neuralgia

74

VZV receptors

4 envelope glycoproteins containing mannose 6 phosphate (Man 6-P) bind Heparan sulphate

75

How is a VZV infection diagnosed?

3 types of lesions simultaneously seen:
1. Maculopapular -
Macule: flat discolored area of skin
Papule: small raised bump
Maculopapular: area that is usually red, and has small confluent bumps
2. Vesicular - bump containing clear fluid and when filled with pus = pustule
3. Scabs

76

What are congenital and neonatal complications of VZV?

can cross the placenta
ranges from mild to fatal
primary infection during pregnancy leads to pneumonia

77

If infection of VZV during 1st 20 weeks of pregnancy, then ..

3% chance of transmission to fetus = Congenital varicella syndrome
scarring of skin
hypoplasia of limbs
CNS and ocular defects
Death in infancy is normal

78

If mother is infected with VZV one week before delivery then

sufficient immunity transferred to fetus

79

What is treatment for chickenpox?

Symptomatic, self limiting
acyclovir may help shorten duration
exclude kids from school until sixth day of rash

80

how is a zoster rash treated?

acyclovir

81

How is Zoster post herpatic neuralgia treated?

low dose tricyclic antidepressants

82

Who is the VZV vaccine recommended for?

live attenuated
for children 12 months of age and seronegative adults
Elderly to prevent zoster (>60 years old)

83

When is VZIG administered?

post exposure prophylaxis in individuals at high risk
mother with varicella 5 days before to 2 days after delivery
IC individuals with no reliable history
offers 3 weeks of protection

84

oral HPV vs. oral HSV?

Herpes - reddened, vesicular lesions - fluid filled
HPV - flesh colored, papular - skin growing out, skin warping, no fluid

85

Family Poxviridae

linear, dsDNA, complex symmetry
brick/box shaped
cytoplasmic replication

86

Transmission of Pox viruses?

respiratory droplets or fomites

87

Molluscum Contagiosum infection

discrete pustules - smooth dome shaped papules
basophilic inclusion bodies
commonly an STD
primarily seen in children
IC/AIDs pt suffer atypical form and forms tumor like growth

88

Hepadnaviridae

Hepatits B virus
ds(partially) DNA
enveloped circular
enters bloodstream and travels to liver to infect hepatocytes

89

Describe the replication of Hep B

includes RNA intermediate that serves as template for progeny DNA strands
so encodes reverse transcriptase (RNAd-DNA pol)

90

What liver pathology can results from a Hepatitis infection?

Chronic
cirrhosis
hepatocellular carcinoma

91

What is the structure of Hep B?

Partially dsDNA with DNA poly at the core
isohedral in shape
surrounded by core antigen which is then surrounded by surface antigen

92

what are the methods of transmission of Hep B?

Sexual, parental and perinatal through milk

93

replication of Hep B in the liver leads to ..

chronic inflammatory repsonse
CD8 cells kill viral infected cells

94

Clinical manifestations of HBV

Hepatitis
Jaundice
multiplies exclusively in liver so continuously seeds blood

95

what is the Hep B incubation period?

60-180 days

96

What is characteristic of an acute HBV infection?

start with fever, rash, arthritis
Jaundice, dark urine, malaise nausea, RUQ pain
the continuous liver inflammation leads to fibrosis of the liver

97

what is characteristic of a chronic HBV infection?

pt did not make surface antibody
so there is constant production of virus
liver cirrhosis

98

Immune tolerant phase of a chronic HBV infection

HBeAg positive
very high HBV DNA
ALT is normal

99

Immune active phase of a chronic HBV infection

HBeAg positive or negative
ALT is elevated
liver histology shows inflammation and fibrosis

100

What does the active HBV vaccine consist of?

recombinant vaccine
HBsAg administered at 0, 1, or 6 months

101

Post exposure of HBV vaccine

Passive vaccine
HBIG - serum from person with high titers of antibody of HBsAg
used to prevent exposure in
infants born to infected mothers, spouses of infected patients and HCW following needle stick injury

102

Diagnosis of HBV

liver function test
-> ALT>AST
-> aspartate, aminotransferase, alanine aminotransferase
Jaundice
RUQ discomfort
Antibody detection

103

HBV treatment

Supportive
HBV immunoglobin (HBIG) post exposure
IFN-alpha
Lamivudine