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Infectious Diseases > Viral > Flashcards

Viral Flashcards

1
Q

T/F: neonatal HIV antibody tests are unreliable

A

TRUE: maternal HIV antibodies can cross placenta and persist in baby for many months, leading to inaccurate testing

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2
Q

how is HIV transmitted

A

blood borne: sexual intercourse, intravenous drug needles or blood transfusions, MTC (mother to child)

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3
Q

what occurs during the seroconversion (acute) phase of HIV infection?

A

first target Langerhans cells (specialized DC cells in epidermis and epithelia), which fuse with CD4+ T cells to spread virus deeper into tissues, including lymph, where much of viral replication takes place (and in blood stream). Macrophages become infected and steadily release HIV into bloodstream (pro-viral reservoir and source of active infection). Viral load is high. Body deploys CD8+ T cells and B cells as alternative response. This causes temporary drop in viral load.

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4
Q

T/F: HIV can replicate in the bloodstream

A

TRUE: replication occurs mostly in lymph tissue and blood stream. Macrophages act as pro-viral reservoir and source of active infection, releasing HIV virions into bloodstream

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5
Q

how does body respond to initial targeting of CD4+ T cells by HIV?

A

deploys CD8+ T cells and B cells - this causes temporary drop in viral load (at end of seroconversion phase, beginning of asymptomatic phase)

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6
Q

what marks the beginning of the clinically latent infection phase of HIV?

A

drop in viral load, due to body deploying CD8+ T cells and B cells

CD4+ T cell count is still steadily declining

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7
Q

what marks the beginning of the third phase of HIV infection, AIDS (acquired immune deficiency syndrome)

A

during asymptomatic phase, CD4+ T cell count steadily declines. Eventually, this leads to dysregulation of B cells. This allows opportunistic infections to develop

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8
Q

what defines AIDS in the US?

A

CD4+ T cell count < than 200 per microliter

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9
Q

maculopapular rash

A

smooth skin rash with elevated bumps, a combination of macules and papules - macules are flat, discolored spots that are not filled with fluid. Papules are small bumps that are solid

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10
Q

How soon after infection can HIV antibody tests detect antibodies?

A

3-12 weeks after infection

can be done as rapid test or in the lab. Antibodies detected sooner in blood than oral fluid

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11
Q

what kind of test can detect HIV infection as soon as virus appears in bloodstream, before antibodies develop (as early as 10 days after infection)?

A

HIV RNA PCR test

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12
Q

what kind of cancer is common among people who have AIDS after developing HIV infection?

A

Kaposi’s sarcoma - develops from cells that line lymph or blood vessels. Appears as abnormal tissue growth on skin or in lining of mouth, throat, lymph nodes. Lesions are red/purple and become life threatening when they appear in lungs, liver, or GI tract.

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13
Q

what are some signs of a serious influenza infection?

A

fever, pallor, tachypnea and SOB, tachycardia, decreased O2 saturation, coarse rhonchi and decreased breath sounds at base of lungs, dry mucous membranes (dehydration)

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14
Q

how does influenza virus enter host?

A

respiratory droplets

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15
Q

what are the two major glycoproteins on surface of influenza virus and what do they do?

A

hemagglutinin - viral binding to respiratory epithelial cells via sialic acid on cell surface
neuraminidase - cleaves sialic acid to release newly formed virions, decreases viscosity of mucous film coating respiratory tract (facilitating spread)

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16
Q

antigenic drift vs antigenic shift

A

drift - point mutations during viral replication, responsible for new virus strains
shift - entirely new virus introduced into human population, occurs when either non-human strain gains ability to infect human host or genetic reassortment occurs between human and non-human strains. Especially dangerous because entire population lacks immunity

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17
Q

Antigenic [drift/shift] can result in worldwide pandemics, which strike approx. once every generation

A

antigenic shift - occurs as result of genomic reassortment between nonhuman and human strain of virus

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18
Q

what are the components of a virion?

A

capsid (outer protein shell), inner core of nucleic acid (DNA or RNA), and sometimes an additional fatty envelope surrounding capsid

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19
Q

what is the other name for Tamiflu, and what is it used for?

A

aka Oseltamivir, antiviral medication used to treat symptoms of influenza. Can also be given as preventive medication following exposure

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20
Q

Acetylsalicylic acid, acetaminophen, and ibuprofen are examples of what type of medication?

A

antipyretic - reduce fever

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21
Q

what is the difference between RSV infection in adults and children? (typically)

A

RSV = respiratory syncytial virus

In adults, causes minor cold. In children, causes bronchiolitis (infection of small airways), usually under age of 2

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22
Q

RSV (respiratory syncytial virus) is nonenveloped or enveloped? DNA or RNA?

A

enveloped RNA virus

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23
Q

What are the two important glycoproteins of RSV (respiratory syncytial virus) and what do they do?

A

F - fusion of virus and host cell PM, forming syncytia that can be seen in vitro (multinucleated cell from fusion of single nucleated cells)
G - targets ciliated cells of airways to cause attachment of virus to cells

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24
Q

most common cause of bronchiolitis and pneumonia in children under age of 1:

A

RSV: respiratory syncytial virus

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25
Q

60yo m pt presents with painful vesicular rash on R side of torso. Upon examination, you find tiny fluid filled blisters. What viral infection do you suspect?

A

classic presentation of shingles (herpes zoster) - skin manifestation of reactivation of varicella zoster virus from chicken pox as a child

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26
Q

varicella zoster virus is a member of the ___ virus family

A

alpha herpes virus family

causes chicken pox in children, shingles in adults

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27
Q

most common means of transmission of varicella zoster virus?

A

respiratory droplets

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28
Q

varicella zoster virus (VZV) displays viral tropism for ___, which allow it to spread throughout the body via the blood stream

A

T cells

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29
Q

varicella zoster virus invades the skin during which phase of viremia

A

secondary viremia (when virus is spreading through bloodstream after second round of replication)

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30
Q

how does varicella zoster virus enter latent phase?

A

taken up by sensory neurons in skin, travels up to dorsal root ganglion. Sensory neurons are immune privileged (good hiding place for virus)

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31
Q

how is varicella zoster reactivated in shingles?

A

hiding in infected sensory neurons during latent phase, then travels back down to cause shingles in dermatome associated with infected nerves

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32
Q

postherpetic neuralgia

A

severe complication of shingles, difficult to treat condition associated with nerve pain from damage to nerve cells by varicella virus - causes abnormal electrical firing that conveys severe pain. Can last for months, years, or in some cases for life

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33
Q

Tzanck smear

A

test to diagnose bullous and vesicular skin lesions caused by herpes simplex, herpes zoster (shingles), and varicella

scape cells from base of skin lesion and stain to look for Tzanck cells (multinucleated giant cells)

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34
Q

when is chickenpox vaccine usually given to children?

A

12-15 months and 4-6 years

35
Q

how can Hepatitis B be transmitted?

A

contact with infected blood, sexual contact, MTC

36
Q

damage to the liver from Hep B infection can be measured by an elevation of what enzyme in the blood?

A

ALT (alanine aminotransferase) - sign of liver damage

37
Q

where does Hep B preferentially replicate?

A

liver, because it has specific transcription factors in hepatocytes necessary for viral replication

38
Q

what is the cause of the extensive liver damage that can occur from Hep B infection?

A

the robust cytotoxic (CD8+) T cell response

39
Q

what is done for babies in the US that are born to HBV infected mother?

A

given both passive immunity (anti-HBV IGs) and active immunity (HBV vaccine) to prevent chronic infection

effective because vertical transmission occurs through birth process, not in utero

40
Q

T/F: HBV vertical transmission from MTC occurs in utero

A

FALSE: occurs from exposure to maternal secretions during childbirth

41
Q

what is HBV composed of (3 things)?

A

core protein, viral DNA, DNA polymerase

these are surrounded by HepB surface antigen (HbsAg)

42
Q

what HBV antigen is a byproduct of replication?

A

Hep B E antigen

43
Q

in patients infected with HBV, presence of ___ antibodies indicate they have successfully resolved their infection

A

antibodies against Hep B surface protein

high levels of HBsAg (antigen) indicate acute or chronic infection, and ability to infect others

44
Q

what kind of cancer can chronic Hepatitis B infection cause, and what are the 2 pathways to developing this cancer?

A

hepatocellular carcinoma, developed by either:
cirrhotic pathway - chronic immune-mediated damage leads to constant cell proliferation and cancer develops
non-cirrhotic pathway - HBV integrates into host genome and induces oncogenic mutations

45
Q

a positive test for this antibody against HBV indicates past or current infection, but does not provide any protection against Hep B

A

anti-HBc or HBcAb (antibody against HBV core protein)

46
Q

chronic hepatitis is commonly caused by infection of either of these 2 viruses

A

Hep B or Hep C

47
Q

MHC I vs MHC II

A

MHC I: on all cell membranes

MHC II: on membranes of APC (macrophages, DC, lymphocytes)

48
Q

___ are macrophages resident in the lumen of liver sinusoids (small blood vessels), which cause much of the immunity-mediated damage during HBV infection

A

Kupffer cells - cause damage via inflammatory activation

49
Q

in a patient with HBV infection, massive death and destruction of hepatocytes and decrease in liver size indicates what syndrome of their infection?

A

fulminant hepatitis - can be life-threatening if it leads to liver failure

50
Q

hepatitis B virion is also known as

A

Dane particle

51
Q

what virus causes mononucleosis?

A

Epstein Barr virus

52
Q

how is EBV transmitted and what illness does it cause?

A

Epstein Barr virus - causes mononucleosis

spread via oral transfer of saliva (“kissing disease”)

53
Q

where does Epstein Barr virus colonization typically begin?

A

tonsils - first epithelial cells than B cells, which leave tonsils and spread virus via lymphatic circulation

54
Q

following Epstein Barr virus infection, proliferation of [CD4/CD8] T cells lead to systemic signs and symptoms of mononucleosis?

A

CD8 - cause release of cytokines, leading to fever and swollen lymph nodes

55
Q

FUO means what?

A

fever of unexplained origin - fever greater than 100.9F (38.3C) that lasts more than 3 weeks

categories include: classic, health care associated, immune deficient, HIV related

56
Q

what are some symptoms of mononucleosis, caused by Epstein Barr virus (EBV)?

A

fever, swollen lymph nodes, headache, sore throat, skin rashes, fatigue, splenomegaly (swollen spleen)

57
Q

what is a simple way to differentiate between mononucleosis (EBV infection) and a chronic illness such as cancer, TB, or autoimmune disease?

A

determine if the patient has been losing weight - common among chronic illnesses, less so with mononucleosis

58
Q

what is another name for mono spot test?

A

heterophile antibody test
If antibodies are present, the blood clumps. Can detect antibodies 2-9 weeks after infection, but may be nonspecific to EBV

59
Q

polio, hand foot and mouth disease, and the common cold are all caused by this type of virus. What is?

A

enteroviruses - RNA virus, targets GI and nervous system

Usually causes mild flu-like upper respiratory illness but can sometimes cause aseptic (nonbacterial) meningitis, viral conjunctivitis, and myocarditis

60
Q

a pt presents with low grade fever, stiff neck, and extreme pain while extending their leg from a position where his thigh is bent at the hip and knee at 90 degrees (Kernig’s sign). When asked to lift their head while lying down, they involuntarily lift their legs, as well (Brudzinski’s neck sign). What does this suggest?

A

nuchal rigidity, headache, fever, emesis (vomiting) suggest meningitis

Nuchal rigidity and Kernig’s sign due to muscle spasms. Brudzinski’s neck sign due to stretch of irritated meninges, leading to painful flexion of lower extremities.

61
Q

what are 3 conditions that could cause an elevation of CSF lymphocytes?

A

viral meningitis, tuberculosis meningitis, and subarachnoid hemorrhage (among other things)

62
Q

T/F: testing for bacterial and viral infections is different in that a specific bacteria needs to be suspected when a physician is selecting the right test

A

FALSE: unlike bacterial cultures, a specific virus needs to be suspected when a physician is selecting the right test to confirm diagnosis

63
Q

T/F: meningitis is neurotropic

A

TRUE: because it is able to invade nervous tissue

64
Q

why would some at risk patients with viral meningitis be given empirical antibacterial therapy, even if viral meningitis is suspected?

A
  1. these patients are at a higher risk for developing bacterial meningitis
  2. they may not mount a vigorous or typical immune response
  3. they may not show early signs of deterioration before becoming very ill
65
Q

Nuchal rigidity, Kernig’s sign, and Brudzinski’s neck sign are all signs of this viral infection. What is?

A

viral meningitis

nuchal rigidity - difficulty bending neck forward due to muscle spasms
Kernig’s sign - difficulty extending knee due to hamstring spasms (patient lies on back, bends knee at right angle, tries to extend knee)
Brudzinski’s neck sign - when patient is supine and flexes neck, reflexive flexion of hips and knees occurs (due to irritated meninges)

66
Q

aseptic meningitis is [more/less] common than bacterial meningitis?

A

aseptic meningitis is more common but less severe with fewer complications

67
Q

This virus is best known for causing symptomatic genital infection in about 10% of sexually active individuals. What is?

A

HSV-2 (herpes simplex virus type 2)

also causes lifelong asymptomatic infection in about 20-30% of adults

68
Q

what is the clinical difference between HSV-1 and HSV-2?

A

HSV-1 most commonly causes fever blisters (cold sores) around mouth and lips
HSV-2 is the most common cause of genital herpes

69
Q

what are the two ways HSV-2 can be transmitted?

A

horizontally (sexual partners), vertically (MTC, during passage through birth canal)

70
Q

HSV-2 preferentially infects ____ initially, then…

A

epithelial cells located in mucosa or at sites of skin abrasion, then it travels up neuronal axons to local sensory ganglia in peripheral nervous system (establishes latency)

71
Q 
the rash found in herpes simplex virus infection most likely resembles:
macules
papules
abscesses
blisters
A

blisters

72
Q

child presents with fever, red/itchy eyes, rhinorrhea, cough, bluish white specks inside mouth (inside of cheeks), morbilliform rash starting at hairline and spreading down face/neck/arms/trunk (small, slightly red raised spots). The child has not received regular vaccinations. What viral infection might you suspect?

A

measles (did not receive MMR/measles, mumps, rubella vaccine)

73
Q

the measles virus spreads so effectively due to its ability to suppress activation of this antiviral warning signal:

A

interferon alpha (stimulates macrophages against viruses)

74
Q

Koplik spots are a sign of what viral infection?

A

bluish white specks inside mouth, on inside of cheeks

sign of measles

75
Q

T/F: measles diagnosis requires reporting to public health agencies

A

TRUE - these respond to prevent a larger outbreak

76
Q

prodromal

A

relates to early symptoms before onset of a disease

77
Q

exanthem

A

widespread red or pink colored rash accompanied by systemic symptoms (fever, malaise, headache), usually caused by virus (such as chickenpox, measles, rubella)

78
Q

measles is also called what

A

rubeola. Spreads via coughing and sneezing, causes red rash to spread over body (starting from head)

79
Q

when are the MMR vaccine doses recommended?

A

for measles, mumps, rubella (German measles)

1st dose 12-15 months, 2nd dose 4-6 years

80
Q

what kind of vaccine is the rotavirus vaccine?

A

attenuated virus (weak but alive)

81
Q

what body region does rotavirus typically colonize and what does it do there?

A

small intestine, where it inhibits absorption, causes water to flow into lumen via osmosis –> diarrhea
Also disrupts tight junctions, making intestine wall more permeable. Also uses cellular machinery to make toxin that causes Cl- secretion into lumen (more diarrhea).
Also stimulates gut nerves to increase motility and more Cl- secretion

82
Q

osmotic diarrhea vs secretory diarrhea

A

osmotic diarrhea - due to ingestion of poorly absorbed substrate (excess solute draws water into lumen)
secretory diarrhea - due to toxin secretion by viruses/ bacteria, leading to prolonged opening of Cl- channels

83
Q

the oral polio virus vaccine, TB vaccine (BCG), measles vaccine (MMR), and rotavirus vaccine are similar in that…

A

they are all live attenuated virus vaccines

84
Q

match IgA, IgG, and IgM with:

a. smallest, most abundant antibodies, found in all body fluids, only to cross placenta
b. found in mucous membranes (esp. resp/GI tracts) and in tears/saliva, protect body surfaces exposed to outside foreign substances
c. largest antibody, found in blood/lymph, first antibody made in response to infection

A

IgA: found in mucous membranes and in tears/saliva, protect body surfaces
IgG: smallest, most abundant, all body fluids, crosses placenta
IgM: largest, found in blood/lymph, first antibody in infection response to be made

Infectious Diseases (3 decks)

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