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Practice topics Exam 1 > Virus 1 > Flashcards

Virus 1 Flashcards

1
Q

What is a virus

A

obligate intracellular parasites

Require the cellular machinery of the host cell for replication

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2
Q

A single virus particle =

What is it comprised of?

A

virion and it is comprised of the viral genome (RNA or DNA) surrounded by a protein coat known as a capsid

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3
Q

How big are viruses

A

TINY

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4
Q

Viral replication

A

They attach to a receptor cell (specificity - not every virus can attach to every receptor)
Requires a lot of machinery from the host for cell transcription

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5
Q

Viral replication - drugs

A

Drugs often are aimed to interrupt the attachment of the virus onto the receptor - they interrupt the packaging process that is needed for replication to occur

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6
Q

Viral transmission - how

A

Most viruses = entry through breaks in skin, across mucus membranes (resp/GI/urogenital)
Some - bite of insects

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7
Q

Viral transmission - most common route of viral infection

A

Inhalation of respiratory droplets

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8
Q

Viral transmission - the route of infection depends on what

A

the site of viral replication within the host
Ex - flu = resp tract = inhalation of droplets
Ex - enterovirsuses = GI = fecal-oral

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9
Q

Route of transmission - Respiratory droplets

A

Influenza
Measles
Varicella Zoster

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10
Q

Route of transmission - GI fecal/oral

A

Hepatitis A, Rotavirus, Poliovirus

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11
Q

Route of transmission - Lesion contact

A

Herpes simplex

Smallpox

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12
Q

Route of transmission - Blood and body fluids

A

Hep B and C
EBV
CMV

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13
Q

Route of transmission - insect bites

A

West nile virus

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14
Q

Viral transmission - some viruses are able to survive in the external environment better than others - which?

A 
Enveloped = very fragile and must remain wet 
Non-enveloped = can withstand harsher environments
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15
Q

Viruses and cancer -

A

Some viral infections can result in uncontrolled cellular growth causing cells to become transformed
End result of this transformation is frequently cancer

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16
Q

Viruses and cancer - Human papilloma virus

A

Cervical cancer

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17
Q

Viruses and cancer - EBV

A

Burkett’s lymphoma

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18
Q

Viruses and cancer - HHV8

A

Kaposi’s sarcoma

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19
Q

Viruses and cancer - Hep B

A

Hepatocellular carcinoma

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20
Q

Antiviral immune mechanisms - natural barriers

A

skin, mucus, gastric acidity, tears, bile

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21
Q

Antiviral immune mechanisms - Nonspecific or innate immune mechanisms

A

Macrophages, neutrophils, monocytes

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22
Q

Antiviral immune mechanisms - Adaptive immune response

A

Antibody and T cell responses - natural killer cells, cytotoxic T lymphocytes

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23
Q

Virus - diagnosis

A

Very difficult!

Reasonable and accurate can be made on clinical presentation (s/s, age)

24
Q

Virus - diagnosis - definitive diagnosis

A

Growing the virus in culture
Detecting viral proteins or genome in clinical material (blood, feces, skin scrapings, swabs)
Detecting antibodies in the pt which recognize a specific virus

25
Q

Antiviral drugs

A

More antibiotics for bacterial infections than viral
Viral is a lot more of preventative drugs
Antivirals tend to be more selective than broad acting antibiotics - antivirals tend to target only a select group or a specific virus

26
Q

Viruses causing skin disease - cutaneous manifestations of viral infection (rash/exanthem)

A

Viral replication in epidermis - HPV, HSV, smallpox

Secondary effect of virus replication elsewhere in body - measles, rubella

27
Q

Viruses causing skin disease - routes of infection

A

Primary infection - mucosal contact, breaks in skin
Secondary - viremia (it infects skin following replication)
!Rash may develop as a result of immune response!

28
Q

Viruses causing skin diseases - childhood exanthems

A 
Chicken pox
Measles
Rubella
Roseola infantum (HHV 6,7)
Fifth disease (parvovirus B19)
29
Q

Herpes Virus - description

A

Large enveloped viruses

Have the ability to enter a latent phase following primary infection, with potential for later reactivation

30
Q

HHV 1

A

Fever blisters, ocular lesions, CNS infections
Think above the waist
1/3 children seropositive by age 5
2/3 adults by age 30

31
Q

HHV 2

A

genital and anal lesions, neonatal infections, CNS infections
Think below the waist
seroprevalence 15-20%

32
Q

HSV 1 and HSV 2 are both transmitted through what

A

direct contact with virus containing secretions
1 = kissing, sharing saliva
2 = sexual contact, infected mother to child with birth

33
Q

HSV 1 and HSV 2 pathogenesis

A

Following inoculation, virus enters and replicates within epithelial cells at site of inoculation
Infection can be asymptomatic or result in lesion
Life long latent infection is typically established in the regional ganglion

34
Q

HS1 and HS2 - mechanisms that trigger reactivation of latent infection are thought to be

A

environmental - UV light, fever, stress, trauma

35
Q

Herpes labialis =

A

cold sore/fever blister

36
Q

Herpes labialis - adutls

A

if primary infection occurs in adulthood, usually asymptomatic
Adults sometimes will develop lesions on the pharynx and tonsils

37
Q

Herpes labialis - incubation period

A

thought to vary from 2 to 12 days
clincial disease resolves in 5-10 days
Viral shedding may occur for weeks

38
Q

Herpes labialis - reactivation is preceded by what

A

a prodrome of pain, burning, tingling, or itching that generally lasts for 6 hours and is followed by vesicle eruption

39
Q

Herpes labialis - lesions will ulcerate and crust over in

A

3 to 4 days

40
Q

Herpetic whitlow =

A

HSV infection of the fingers and nails, following inoculation of secretions into small cuts
Usually occurs in children, individuals with genital herpes, and physicians, dentists and healthcare providers who treat herpes patients

41
Q

Herpes gladiatorum =

A

An infection of the body (skin) - Most commonly observed in wrestlers and rugby players

42
Q

HSV 1 and HSV 2 - diagnosis

A

1 -Can be confirmed by sampling material at the base of a lesion (Tzanck smear)
And demonstrating the presence of multinucleated giantt cells or Cowdry type A inclusions
2 -cultivation of the virus in tissue culture and observation of characteristic cytopathic effect (CPE)
3 -PCR techniques

43
Q

HSV 1 and HSV 2 - Treatment

A

Acyclovir and related compounds
Modest benefit in tx of herpes labialis - can do proph
Topical therapy of eye infections with acyclocir

44
Q

HSV 1 and HSV 2 - prevention and control - health care workers with HSV on figners and hands

A

restricted from contact with patients until lesions are healed

45
Q

HSV 1 and HSV 2 - prevention and control - personnel with orofacial lesions

A

should be counseled to cover their lesions and not touch lesions with their hands
Case by case analysis for those with orofacial and deciding their exposure to high risk patients that are immuno compromised

46
Q

HHV 3

A

Varicella zoster virus causes two diseases
Varicella (chicken pox)
Zoster (shingles)

47
Q

HHV 3 - primary vs. latent

A

Chicken pox develops after primary infection

Shingles results from reactivation of latent virus

48
Q

HHV 3 - Thought to be transmitted primarily though

A

respiratory droplets

Extremely contagious!

49
Q

HHV 3 - transmission

A

virus can be isolated from skin lesions but is difficult to isolate from resp tract
VZV can be transmitted to others for 1-3 days prior to the onset of the rash

50
Q

HHV 3 - pathogenesis

A

Virus becomes latent in sensory ganglia (usually trigeminal and dorsal root ganglion)
Lesions have characteristic dermatomal clustering
With reactivation, virus replicates and is released along neuronal pathway

51
Q

Chicken pox - description

A

No evidence of prodrome in children, adults may experience 1/2 days of malaise and fever
Fever and rash appear simultaneously on trunk and head rather than extremetites
Lesions appear in crops
Within 12-24 hrs will crust and scab over

52
Q

Shingles - description

A

lesions occur unilaterally along dermatome supplied b y adorsal route or CN sensory ganglion
Severe pain typically precedes the eruption
Postherpetic neuralgia may persist

53
Q

HHV 3 - treatment

A

Several compounds including acyclovair can work if administered within 24 hrs of onset - reduce number of lesions and duration of fever (not usually used in kids)

54
Q

HHV 3 - prevention/control

A

live attenuated vaccine

given to children at 12-18 months of age and is also recommended in adults over 60

55
Q

HHV 3 - prevention/control - healthcare workers who develop it should

A

be excluded from work until all lesions have crusted over and dried
exclude from duty personnel who have been exposed to it and are not known to be immune

56
Q

HHV 3 - work restrictions should be in effect from

A

10 th day after first exposure to the 21st day after last exposure

Practice topics Exam 1 (15 decks)

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