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Clin Micro > Exam 4 Practice Questions > Flashcards

Exam 4 Practice Questions Flashcards

1
Q

Describe the genome and symmetry of HAV

A

Single stranded positive RNA surrounded by naked icosahedral capsid

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2
Q

THe 5’ end of the RNA strand of Hep A has a protein called _____.

A

VPg

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3
Q

What is the most common transmission for hep A? Other modes of transmission?

A

Most common: oral-fecal

Other: sexual, IV drug use, blood borne

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4
Q

Which hepatitis virus accounts for most of the hepatitis cases?

A

Hep A

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5
Q

What is the pathology of Hep A?

A

Orally ingested -> enters bloodstream via GI lining -> migrates to the liver -> incubation period (prodrome) of 15-40 days -> sudden onset of symptoms -> recover in 8-12 weeks 99% of the time

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6
Q

What are the symptoms of all hepatitis causing viruses?

A 
Fever
Headache
Vomitting
Jaundice
Abdominal pain due to liver inflammation
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7
Q

How is Hep A treated?

A

Prevention via proper sanitation and vaccination

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8
Q

What is the most common mode of transmission for the hepatitis A virus?

Select one:

a. fecal-oral route
b. respiratory
c. IV drug use
d. sexual transmission

A

a. fecal-oral route

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9
Q

Which of the following is true regarding hepatitis A?

Select one:

a. most people recover completely
b. most people develop chronic infection
c. some people develop chronic infection
d. IV drug use is the most common way to contract Hep A

A

a. most people recover completely

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10
Q

Describe the genome and symmetry of HBV

A

incomplete DNA virus that is enveloped

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11
Q

Serum hepatitis is referring to _____

A

HBV

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12
Q

Infectious hepatitis is referring to _____

A

HAV

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13
Q

HBV virons are also known as _______ _______

A

Dane particles

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14
Q

What are the top three blood borne pathogens?

A

Hep B, Hep C and HIV

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15
Q

What is unique about HBV replication?

A

The double stranded genome of HBV is completed by enzymes contained in the core of the virus after is enters the cytoplasm of the host cell

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16
Q

How is HBV transmitted?

A
  • Contact with body fluids (usually blood but can be vaginal secretions, menstrual blood, saliva and breast milk)
  • IV drug use
  • sexually
  • neonate during birthing process
  • tattoo, piercing, acupuncture
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17
Q

What is the incubation period for HBV?

A

50-180 days

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18
Q

What are the disease patterns of HBV?

A

If immune response is robust, it can be self limiting and resolve. If immune compromised, can result in chronic hepatitis leading to cirrhosis, liver cancer or liver failure

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19
Q

How is severity of symptoms and probability of chronic infection related with HBV infection.

A

Inversely, meaning the fewer symptoms you have, the more likely you are to develop chronic infection

The younger you are, the fewer symptoms, the more likely chronic infection. Newborns are now being vaccinated

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20
Q

How can an acute HBV infection be distinguished from a chronic HBV infection?

A

The presence of antibodies (IgM) against HBsAg

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21
Q

How is HBV treated/prevented?

A
  • Active or passive immunization

- avoid contact with blood or blood products

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22
Q

What type of virus is hepatitis B?

Select one:

a. an incomplete DNA virus
b. a negative strand RNA virus
c. a positive strand RNA virus
d. a complete DNA virus

A

a. an incomplete DNA virus

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23
Q

What is the most common way to acquire a hepatitis B infection?-

A

unprotected sex

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24
Q 
Individuals with chronic hepatitis B are at increased risk of:
Select one:
a. liver cancer
b. respiratory infection
c. lung cancer
d. contracting hepatitis A
A

liver cancer

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25
Q

A vaccine is available for:

Select one:

a. Hepatitis B
b. Hepatitis C
c. HIV

A

HBV

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26
Q

Hep C is also referred to as _______

A

Non A, non B hepatitis

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27
Q

Describe the genome and symmetry of HCV

A

Positive strand RNA, enveloped, icosahedral

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28
Q

What are the known reservoirs of HCV?

A

Humans and chimps

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29
Q

What are the common modes of transmission for HCV?

A
  • IV drug use (most common)
  • blood transfusions
  • sexual intercourse
  • occupational exposure to blood
  • tissue transplant
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30
Q

HCV is more resistant to ______ than HIV and can survive for several days on needles, etc.

A

Drying

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31
Q

Is HCV usually cleared or does it usually become chronic?

A
  • usually becomes chronic. It is cleared in 15-25% of patients
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32
Q

Because HBV and HCV can be chronic, who can pass the virus on?

A

Any positive (HCV+ or HBV+) person

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33
Q

How is HCV diagnosed?

A
  • Highly specific ELISA test, however the antibodies for this do not appear until 8-20 weeks after infection
  • PCR can be used to detect RNA earlier
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34
Q

What is the treatment fo HCV?

A
  • Ribivirin + interferon but this resolves only 50% of chronic HCV
  • new, more effective medication available but too expensive to be widely used
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35
Q

A common route of transmission for hepatitis C is:

Select one:

a. IV drug use
b. fecal-oral
c. respiratory
d. direct contact

A

IV drug use

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36
Q

Hepatitis C, like other hepatitis viruses, target ________________.

A

Hepatocytes

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37
Q

Which of the following is true of hepatitis C?

Select one:

a. a vaccine is readily available
b. drug treatment is available
c. most recover without treatment
d. it can be passed through casual contact

A

b. drug treatment is available

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38
Q

What does it mean to say the HDV (aka Delta agent) is an incomplete virus?

A

It cannot code for its own surface proteins and therefore need a helper virus, HBV, to produce more virus particles

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39
Q

How is HDV transmitted?

A

Most commonly by IV drug use but also can be sexually transmitted

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40
Q

What are the typical symptoms of HDV?

A

HDV super infects an already HBV infected patient and causes acute hepatitis symptoms that resolve

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41
Q

How is HDV treated/prevented?

A

Prevent by vaccination for HBV, because HDV depends on HBV for productive infection
No treatment for HBV or HDV

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42
Q

Which of the hepatitis viruses are blood borne?

A

B, C, D

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43
Q

Which of the hepatitis viruses are transmitted but oral fecal route?

A

A, E

A can also be transmitted by direct contact, while E cannot

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44
Q

Describe the genome and symmetry of HEV

A

Positive strand RNA, naked, icosahedral

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45
Q

What is the incubation period for HEV?

A

16-60 days

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46
Q

Which hepatitis viruses have no chronic infections?

A

HAV and HEV

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47
Q

Can HEV or HAV be fatal?

A

Yes, but rarely

Only in immune compromised/pregnant

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48
Q

Hepatitis D requires which other virus to infect liver cells?

A

Hep B

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49
Q

What is the route of transmission for the hepatitis E virus?

A

Fecal oral

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50
Q

Describe the genome and symmetry of the influenza virus

A

Single stranded RNA virus consisting of 8 RNA fragments, enveloped, spherical

51
Q

What family does the influenza virus belong to?

A

Orthomyxoviridae

52
Q

There are three types of influenza viruses, A,B,C. What determines whether a particular virus is A.B or C?

A

The internal antigens IM1 and NP)

53
Q

Within the types of influenza viruses (A,B,C) there are subtypes that are determined by what?

A

External antigens of the viral envelope (HA and NA glycoproteins)

54
Q

Major outbreaks are associated with what types of influenza virus and which has milder symptoms?

A

A and B, with B having milder symptoms

55
Q

Which type of influenza virus is indistinguishable from the common cold?

A

Type C

56
Q

What is type A so problematic?

A

It changes a lot every year and is found in both animals and humans

57
Q

Which type of mutation in influenza virus results in a more rapid change, Antigenic drift or antigenic shift?

A

Antigenic shift

58
Q

What occurs in antigenic shift?

A

New HA or NA glycoproteins are made. Internal antigens are unchanged

59
Q

Where does the new HA and NA come from that causes antigenic shift?

A

An animal, usually a duck, becomes infected with both a human and animal influenza virus. Reassortment of the viruses occurs during replication, such that the internal components of the new virus are human and the HA and/or NA glycoproteins are from the animal virus

60
Q

How is flu transmitted

A

Aerosolized particles from respiratory tract or infected surfaces

61
Q

What is the incubation period fro influenzae?

A

24-48 hours

62
Q

What is the pathogenesis of influenza?

A

Respiratory cells die due to effect of the virus. This causes cilia to also die, which reduces ciliary clearance or infectious agents from the respiratory tract.

63
Q

What is Reye’s syndrome?

A

Rare encephalitis that follows certain viral infections (influenza and chicken pox), especially in children treated with aspirin

64
Q

How is the flue treated?

A

Primarily by prevent with the annually formulated trivalent vaccine but some medication due exist (Tamiflu, relenza) that treat the flu

65
Q

What is Guillain Barre syndrome?

A

Idiopathic disease in which the body damages its own nerve cells (outside CNS), causing muscle weakness and paralysis

66
Q

Was is the relationship between Guillain Barre syndrome and influenza?

A

Guillain Barre syndrome was associated with vaccination with the swine flu vaccine in 1976

67
Q

How does H5N1 influenza affect humans and animals?

A
  • humans are infected by contact with duck or other infected bird, not each other
  • Highly virulent and causes death in 6 out of 18 humans and most domestic poultry
  • remains as a silent in ducks, making them a reservoir
68
Q

Antigenic drift is due to:

A

Mutation

69
Q

If in 2012 the major circulating strain of influenza was H3N2, and then in 2013 the major circulating strain was H1N1. How would you describe this change?

A

Antigenic shift

70
Q

Which of the following groups is at highest risk of deaths due to influenza?

Select one:

a. the elderly
b. pregnant women
c. athletes
d. MSM (men who have sex with men)

A

Elderly

71
Q

A child under the age of 12 with an influenza infection should not be treated with aspirin due to the risk of __________________.

A

Reye’s syndrome

72
Q

How does Tamiflu function to help limit an influenza infection?

A

it prevents new viral particles from being released from host cells

73
Q

Describe the genome and symmetry of picornaviridae

A

Positive strand RNA virus, naked, spherical, small

74
Q

What is the most common disease pattern for those infected with poliovirus?

A

asymptomatic

Other patterns include:

  • abortive
  • non-paralytic
  • paralytic
75
Q

Non-paralytic polio is ____________________.

A

aseptic meningitis

76
Q

What type of vaccine is the Salk vaccine for polio?

A

inactivated

77
Q

What is the route of transmission for Coxsackie viruses?

A

fecal-oral

78
Q

Which of the following is attributed to Coxsackie type A viruses?

Select one:

a. hand foot and mouth disease
b. myocarditis
c. pluerodynia
d. pericarditis

A

a. hand foot and mouth disease

79
Q

What is the most common route of transmission for rhinovirus infection?

A

Respiratory

80
Q

The virus that causes SARS is a typical ___________________.

A

Coronavirus

81
Q

Deaths attributable to rotavirus are due to _________________.

A

dehydration

82
Q

Symptoms of rotavirus infection include:

Select one:

a. watery diarrhea
b. cough and runny nose
c. pain on urination
d. ulcers in the oral cavity

A

watery diarrhea

83
Q

Rabies virus enters at the site of the bite, moves to the dorsal root ganglion and then moves to the ______________.

A

Brain

84
Q

Which of the following is a unique symptom of rabies infection?

Select one:

a. hydrophobia
b. photophobia
c. arachnophobia
d. claustrophobia

A

Hydrophobia

85
Q

A diagnostic indicator of rabies infection is _____________.

A

Negri bodies

86
Q

How is equine encephalitis virus transmitted?

A

Mosquito

87
Q

West Nile virus is vectored by the _____________.

A

Mosquito

88
Q

Most individuals infected with the West Nile virus ________________.

A

Are asymptomatic

89
Q

What is the vector for the yellow fever virus?

A

Mosquito

90
Q

A vaccine is available for which of the following viruses?

Select one:

a. ebola
b. yellow fever
c. dengue fever
d. West Nile

A

Yellow fever

91
Q

Dengue fever is characterized by which set of symptoms below?

Select one:

a. fever and muscle/bone pain
b. cough and runny nose
c. pain on urination and ulcers
d. severe bleeding and pain

A

fever and muscle/bone pain

92
Q

Having had dengue fever, a second infection with a different version of the virus is likely to result in _____________________.

A

hemorrhaging from many body locations

93
Q

What is the vector for the chikungunya virus?

A

mosquito

94
Q

When did the chikungunya virus first emerge in the Americas?

A

2013

95
Q

Which of the following is a zoonotic virus (virus acquired from a non-human animal source)?

Select one:

a. West Nile
b. hantavirus
c. yellow fever
d. lassa fever

A

hantavirus

96
Q

How is the ebolavirus transmitted?

A

via contact with infected blood

97
Q

Which of the following enzymes must a retrovirus bring with it as it infects a human cell?

A

Reverse transcriptase

98
Q

HTLV viruses can induce _____________ in human cells.

A

Cancer

99
Q

HIV-1 is most closely related to _____________.

A

SIV cpz

100
Q

HIV-2 is most closely related to _____________.

A

SIV sm

101
Q

What is the most common subtype of HIV-1 in North America and Europe?

A

B

102
Q

Which part of the HIV virus interacts with the CD 4 receptor on a T cell?

A

GP 120

103
Q

Which enzyme allows the DNA of HIV to enter the host’s DNA?

A

Integrase

104
Q

After HIV binds to GP 120 what must happen for the virus to enter the host cell?

A

a co-receptor must be bound

105
Q

How does HIV exit a T lymphocyte?

A

lysis of the host cell

106
Q

What enzyme is responsible for liberating other enzymes (Gag-Pol) during the assembly of new HIV virions?

A

protease

107
Q

Which of the following is NOT a possible route of transmission for HIV?

Select one:

a. contaminated needles
b. sex with an infected individual
c. a mosquito bite
d. a blood transfusion

A

a mosquito bite

108
Q

During sexual transmission of the virus, what cell first interacts with the HIV virus in the susceptible partner?

A

dendritic cell

109
Q

When would you anticipate an HIV+ patient having the highest titer of virus?

A

4-10 days after infection

110
Q

If an individual tests negative for the HIV virus 2 weeks after an occupational exposure should she be considered definitely HIV-?

A

No

111
Q

The period of time during which T cell destruction is balanced by appropriate immune response and production of additional T cells is termed _____________.

A

Dynamic equilibrium

112
Q

What defines the onset of AIDS?

A

onset of opportunistic infections

113
Q

What, in part, helps explain the variation seen in the HIV virus within a single patient?

A

high mutation rate of reverse transcriptase

114
Q

Drug resistance seen in some HIV strains is due, partially, to:

A

Mutation

115
Q

The majority of HIV+/AIDS patients reside in _____________.

A

Africa

116
Q

Currently in the US, which group represents the highest number of HIV diagnoses?

A

MSM (men who have sex with men)

117
Q

Which of the following carries the highest risk of exposure to health care workers?

Select one:

a. needle stick
b. blood in the mouth
c. a paper cut
d. blood in the eyes

A

Needle stick

118
Q

What is the most commonly used test for HIV diagnosis?

A

ELISA, although PCR can also be used

119
Q

The highest titer of HIV can be expected in which of the following patients?

Select one:

a. AIDS patients
b. patients with a T cell count of 400/cc of blood
c. patients that have been HIV+ for 2-5 years
d. patients that have been HIV+ for 10 or more years

A

AIDS patients

120
Q

The first HIV drug that was released to market was AZT, what type of drug is AZT?

A

reverse transcriptase inhibitor

121
Q

To best preserve T cell function, HIV+ patients typically:

A

take a combination of anti-retroviral drugs

122
Q

Which type of vaccine would be the safest for vaccinating for HIV?

A

Subunit, although not super effective

123
Q

True or false. A vaccine to prevent HIV is currently available as of summer 2016.

A

False, Many vaccines have been developed, but none are approved or available.

Clin Micro (9 decks)

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