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Major DNA viruses Flashcards

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1
Q

Molluscum Contagiosum

A

Poxviridae

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2
Q

B19

A

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

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3
Q

What sort of cells does B19 preferentially infect?

A

mitotically active erythroid precursor cells in the bone marrow
infects proerthyroblast

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4
Q

Describe the lytic phase of B19

A

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

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5
Q

Describe the non infections immune response of B19

A

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

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6
Q

What is important for clearing B19?

A

IgG

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7
Q

what causes common rash illness in school aged children?

A

B19

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8
Q

lacy reticular maculopapular rash on trunk and extremities

A

B19

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9
Q

Rash appears with IgM

A

B19

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10
Q

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

A

Aplastic crisis - drop in RBCs

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11
Q

concerns with Intrauterine infection of B19

A

hydrops fetalis or fetal death

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12
Q

Rash appears with IgM

A

B19

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13
Q

How would you treat acute vs. chronic B19?

A

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

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14
Q

Adenovirus

A

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

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15
Q

Pathogenesis of Adenovirus

A

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

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16
Q

Where can Adenovirus persist?

A

in tonsils and adenoids in childern

in intestines in adults

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17
Q

How does Adenovirus interfere with host defenses?

A

interferes by blocking IFN and T cells

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18
Q

Viral oncogenes of Adenovirus

A

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)

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19
Q

What are some clinical manifestations of Adenovirus

A

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

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20
Q

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

A

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

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21
Q

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?

A

Adenovirus

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22
Q

papillomaviridae

A

HPV

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

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23
Q

Papilloma

A

benign
squamous epithelial growth
wart
verruca

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24
Q

HPV encodes proteins that promote

A

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

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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

CMBM exam 3 (24 decks)

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