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Flashcards in Microbiology III Deck (177):
1

How does the cell produce an immune response toward virus?

Viral proteins cut up
Class I HLA presents
Cytotoxic T-cells destroy
Ab intercepts

2

T/F
All known life has viruses

True

3

What does a fast mutation of "spikes" mean?

Epitopes change and Antibody can't recognize

4

What are 4 possible genome categories for viruses?

dsDNA
dsRNA
ssDNA
ssRNA

5

What surrounds the genetic material in a virus?
What shape is it?

capsid

icosahedral or helical

6

After replicating, what are the 2 ways a virus leaves a cell?

Budding (envelope with spikes)
Lysis

7

Lytic viruses are...
Non-lytic viruses are...

Naked
Enveloped

8

A Latent virus, like Herpes, can be...
HPV cause cancer because they...

Latent
Transformation (hyperproliferation)

*hyperproliferation causes the cell to divide, thereby replicating the virus that is part of the genome

9

Aside from being enveloped or non-enveloped, a virus can be...

Complex
(characteristics of both)

10

Define sense and antisense:

sense (+): same as mRNA
antisense (-): same as template DNA

11

What are the 4 structural possibilities for a virus?

Icosahedral (naked or enveloped)
Helical (naked or enveloped)

12

plus(+) sense ssRNA viruses must bring what with it?

RNA-dependent RNA polymerase
makes template strand for ssRNA sequence for every replicated virus

*sense strand directly codes for proteins
**type I virus

13

anti-sense(-) ssRNA viruses must bring what with it?

RNA-dependent RNA polymerase
anti-sense(-) to sense(+)

*sense strand codes for proteins AND (-)ssRNA
**type II virus

14

Upon entering the cell, what does dsRNA need to replicate?

RNA-dependent RNA polymerase to make sense(+) strand from DNA template.

AND to make dsDNA from (+)sense strands

*sense strand makes mRNA's and viral proteins
**type III virus

15

Describe the replication of Type IV (+)ssRNA.

sense strand enters
Viral RNA-dependent DNA polymerase creates (-)DNA
Viral RNA-dependent DNA polymerase creates (+)DNA
host cell integration
all host machinery from here

*aka Reverse Transcriptase

16

T/F
RNA viruses need their own polymerase at some step, while DNA viruses do not.

True

17

T/F
(+)ssRNA are the only viruses that don't need to bring a polymerase with them into the cell.

True

they are already mRNA, so code for needed proteins

18

What are viruses that lack capsids?

What do they infect?

Viroids
(free nucleic acids)

Infect only plants

19

What are infectious proteins?

Prions

20

Infections are spread:
Horizontally
Vertically

person to person

mother to neonate

21

What is the low profile of an infectious agent called?

Iceberg effect

22

What is required for a pathogen to have a big iceberg effect?

Many carriers (infectious, no symptoms)

23

Name two diseases that exhibit large iceberg effects?

Polio (huge)
Measles

24

How does antigen at one mucosal site stimulate antibody protection at all others?

IgA reacts with Ag at all sites
APC's cause T and B to react and clone
Daughter B cells migrate to other mucosal sites

25

What receptor is integral in moving new IgA from B-emmigrant cells onto mucosal surface?

poly-lg Fc receptors

(takes off B cells)

26

What protects sIgA dimers from proteases on the mucosal surface?
Where does this come from?

secretory component

protease that cleaved sIgA from poly-lg Fc receptor

27

How does sIgA protect neonates?

Through mother's milk
Stays in intestinal lumen

28

What 2 places does a baby's passive immunity come from?

sIgA in gut through milk
IgG through placental transfer

29

IgA found outside the body is _____, while IgA found inside the body is typically ______.

Dimeric
Monomeric

30

T/F
sIgA is a poor activator of Complement and an inconsistent opsonizer.

True

31

What does anergy refer to in oral tolerance?
What is the main inhibitory cytokine involved?

High Ag feeding induces tolerance
TGF-beta

32

What is the immunoglobulin complex that sticks to mucins?
What is this resistant to?
What does it block?

sIgA2
Proteases
Colonization

33

What are the specialized APC's found in the mucosa?

M-cells

34

What does sIgA stick to on mucosal surfaces?

mucins

35

What type of virus is Polio?

Picornavirus

36

Polio is enveloped/naked
is a (what stranded) RNA
usually found what part of body

Naked
(+)RNA
enterovirus

37

Where does Polio bind in the body and replicate?

Oropharynx/GI tract

38

How is Polio transmitted?
What are its viremic effects?

Oro-fecally
Neurotropic

39

What prevents initial colonization of the Polio virus?
What prevents viremia?

sIgA
IgG

40

What Polio vaccine is killed and induces IgG?
Which one is attenuated-live and induces sIgA and IgG?

Salk
Sabin

41

What are the Oro-Fecal considerations of the Polio vaccines?

Salk - 2 month window of continued fecal Polio excretion

Sabin - Fecal sIgA will confer bystander immunity

42

Even though it confers IgG, sIgA, and bystander immunity, what is a downside to the Sabin vaccine?

Can infect immunocompromised

43

Because Polio is a non-enveloped virus, it is very...

Hardy

44

T/F
Poliomyelitis causes permanent damage.

True

*destroys motor neurons in the spinal cord

45

How big is the iceberg effect in Polio?
How many infected are paralyzed?

95% asymptomatic
0.5%

46

Where is the reservoir for Polio?

Humans

*only infects humans

47

How long is the Polio virus present in stool?

3-6 weeks

*long infective period

48

When was the "last case" of Polio in US?

1981

*Global eradication goal of year 2000 not met

49

What type of virus is Influenza?
family?
enveloped/naked?
+/- RNA/DNA?

Orthomyxovirus
Enveloped
(-)ssRNA

50

What must Influenza bring with it into the cell?

Functional RNA polymerase

*-ssRNA virus

51

What allows the Influenza virus to so effectively mutate?

It is a segmented virus

*allows for genome mixing

52

What are the 2 important spike proteins of influenza?
Why are they important?

N - neuraminidase
H - hemagglutinin

complete segments are exchanged with other viruses in the cell.

53

What is the mixing of different expressions of the N and H protein called?

Antigenic shift

*can cause Pandemics

54

What is a viral point mutation causing new epitope expression called?

Antigenic drift

55

H and N of the following:
2009 swine flue
avian influenza

H1N1
H5N1

56

Why are RNA viruses more mutagenic than DNA?

lacks "spell check" mechanism

57

When influenza infects a cell
__ gets in
__ gets out

H
N

*these are both Spike proteins

58

Where does influenza replicate in the cell?

Nucleus

59

T/F
Hemagglutin facilitates viral attachment
Nuraminidase helps viral release

True

60

What is a fast way to determine if someone is carrying antibodies to a specific influenza strain?

Hemagluttination Inhibition Assay

61

What causes many deaths from Influenza?

Lung becomes "denuded" and susceptible to secondary opportunists (staph and strep)

62

What identifies the 3 Influenza types?
What are they?
Which cause human disease?

Capsid antigens
A,B,C
A and B

63

What does it mean that flu vaccines are usually "trivalent?"

They have 2 A and 1 B component

64

What do the following Antiviral Drugs do?
Amantadine and Rimantadine
Oseltamivir (Tamiflu) and Zanamivir (Relenza)

Blocks viral uncoating
Inhibits neuramidase viral release from cell

65

Influenza Pandemics most often come from _____ and epidemics most often come from _____.

Type A
A and B

66

What determines the subtypes of the A influenza virus?

Hemagglutinin
Neuraminidase

67

How many types of Hemagglutinin are there?
Neuraminidase?

16
9

68

What is the reservoir for Type A influenza?

Animals

*we can't vaccinate ourselves out of the disease

69

What does Type A influenza cause?

Epidemics and Pandemics

70

What is the reservoir for Type B influenza?

Humans only
(milder, mostly young and old are infected)

71

With influenza, what type of mutation is major?

Shift mutation

*this causes new subtypes of H and N

72

What causes minor mutations in influenza?

Drift mutaions

*point mutations

73

How is the inactivated flu vaccine administered?
Activated/attenuated?

shots
mist

74

How does the Quadravalent flu vaccine differ from the Trivalent?

Quad - 2 most probable A and B types

75

What is the average efficacy of the influenza vaccine?

60%

*depends on age, works poorly with elderly

76

What are the normal animal vector pathways used by the Influenza virus?

Fowl to Pig to Human

(or vice versa)

77

What does Hepatitis mean?

Inflammation of the Liver

78

There is no cross immunity of the Hepatitis viruses with what exception?

HBV and HDV

79

What is the viral load in the blood with both HBV and HCV?

Huge.

80

With so many viruses that damage the liver, how do we determine a Hep virus?

If it lives in and damages hepatocytes

81

What blood factor is increased by Hep virus liver damage?

Transaminase

82

Which Hepatitis viruses are non-enveloped?
How are they transmitted?

HAV and HEV
oro-fecally

83

Which Hep viruses are enveloped?
How are they transmitted?

HBV, HCV, HDV
vertical, sex, droplets

84

Which Hep viruses have no chronic condition?

Hep A and Hep E

*either live or die, Acute Only

85

What 2 ways can we prevent Hep A infection?

HAIG (immune globulin) - can be used pre or post infection

Vaccine

86

T/F
Hep B has immunoglobulin therapy and available vaccine.

True

HBIG and vaccine

87

T/F
There are no products that prevent HepC

True

*although there is now an expensive $84k cure

88

What does HBV prevention also affect?

HDV

89

T/F
There are no prevention measures for HEV other than sanitation measures

True

90

What demographic is susceptible to HEV?

Women 3rd Trimester
20% Die

*Developing countries

91

What Hep causes most deaths/yr in the US?

HCV
20k chronic

92

T/F
Fulminant (acute) Hep death is rare.

True

93

HAV virus:
type?
enveloped/naked?

Picornavirus (+ssRNA)
Naked

*sturdy and acute

94

T/F
HAV has a single serotype worldwide

True

95

T/F
HAV can be asymptomatic

True

96

T/F
HAV vaccine has been available since the 1960's

False
1996

97

Does HAV have carriers?
Why?

No
Acute (or asymptomatic) infection only

*after which immune

98

HBV:
type?
enveloped/naked?

dsDNA Hepadnaviridae
Enveloped

99

T/F
There is single worldwide serotype for HBV

True

100

T/F
There can be an acute, asymptomatic, or chronic infection with HBV.

True

101

If exposed to HBV, what is the rate of developing a chronic infection for an adult?
For a baby?

10% (90% resolution)

90% (25% go on to major consequences)

102

T/F
HBV vaccine has been available since 1981

True

*inactivated

103

What is the primary component of the Hepatitis B vaccine?

HBsAg
(surface antigen)

*this is a Spike Protein

104

Why are health care personnel so at risk for HBV?

very big viral loads among chronically infected

105

What are the 2 major consequences of chronic HBV?

Liver tumors
Cirrhosis

106

What is responsible for the pathology surrounding HBV?

Cell-mediated immunity and inflammation

*this also eliminated HBV infection

107

T/F
HBV is double-stranded DNS virus

True

108

What 3 immune components eliminate HBV in 90% of adult cases?

B, Th, and Tc

109

dsDNA virus in HBV goes DNA RNA RNA DNA

True

110

T/F
There is no treatment for Chronic HBV

True

*unlike HCV (new)

111

How do retroviruses reverse the process of the host cell?

Enter as (+)ssRNA
(mRNA equivalent)
converted to dsDNA

112

T/F
HIV is a diploid virus.

True

113

T/F
HIV frequently changes host range and causes tumors inhumans

True

114

What is the enzyme in retroviruses that transcribes RNA to DNA?

Reverse Transcriptase

115

Exogenous viruses are transferred...
Endogenous viruses are transferred...

Horizontally
Vertically (these are integrated into germ line)

116

What is a sexually transmitted human leukemia?
Where is it endemic?

HTLV-1
Japan, SE asia

117

HIV-1 and HIV-2 are what type of Retrovirus?

Lentivirus

118

What percentage of the human genome is made of past retrovirus?

8%
(almost all turned off)

*endogenous

119

What are the 3 Exogenous retrovirus families?

Oncovirus
Lentivirus
Spumavirus

*spuma has to overt pathology

120

Why are STI's a major risk factor in contracting HIV?

Some cause ulcers, and any breach in mucosa greatly increases risk

*Chlamydia type in Africa causes ulcers

121

T/F
Babies born to mothers with HIV generally carry the disease

False

If Mother is on anti-retrovirals good chance child HIV free

122

How many people have HIV worldwide?
New infections/yr?

35 million
2 million

123

How many deaths are there from HIV worldwide per year?

1.6 million

124

What type of HIV causes the preponderance of infection?

HIV-1

125

Why do Anti-HIV drugs eventually stop working?
What is generally the 1st symptom of crisis phase?

High mutation
Thrush

126

What makes up the ends of HIV?
What makes up the spike complex?

LTR - long terminal repeat
GP120 and GP41

127

What protein in HIV is targeted by a number of protease drugs?

Reverse transcriptase

128

Describe how HIV enters a cell.

GP120 binds first to CD4
GP41 binds and activates Chemokines

129

What is the receptor for GP120?
What is the receptor for GP41?

CD4
CCR5

130

What cells have CD4 and CCR5 receptors?

Th (mostly)
macrophage (some)

131

What are the 6 steps of HIV replication?

Attachment
Entry
Reverse Transcription
Integration
Transcription/Translation
Assembly of new HIV

132

What base deletion is responsible for HIV resistance?
What percentage has this in both alleles?

CCR5
1% northern europeans

*CCR5 removal VERY promising HIV therapy

133

What is the current treatment for HIV?

HAART - Highly active anti retroviral therapy

(5 drugs)

134

Why is a dentist often the first to notice AIDS?

Oral diseases appear first as Th cells fall below 200.

135

What is the most communicable disease?

Measles

aka Rubeola

*300k keeps infection going

136

T/F
There is no iceberg effect with measles

True

*because of its communicability

137

What class of virus causes Measles?
Enveloped/nake?
RNA/DNA?

Paramyxovirus
Enveloped
-ssRNA

138

How is measles transmitted?

Respiratory droplets

139

What causes the characteristic Measles rash?

Tc cells targeting infected capillary endothelium

140

T/F
Cytotoxic T-cells (Tc) and Immunoglobulins usually completely eliminate measles.

True

141

What feature in Measles infection synergizes with poverty and malnourishment?

Immune Amnesia

*Measles targets memory cells causing window of immunosuppression

142

What 2 diseases are caused by (-)ssRNA Paramyxovirus?

Measles and Mumps

143

What is the main difference between Measles and Mumps?

Mumps has an iceberg effect

*Measles has no asymptomatic carriers

144

What is the characteristic symptom of Mumps?

Parotitis

(painful swelling of salivary glands)

*can also infect testicular ducts

145

What is German Measles?

Rubella

146

T/F
Rubella is comparatively benign

True

147

When would a fetus be at risk for Rubella?

1st Trimester

*leads to birth defects

148

Rubella:
type?
Enveloped/naked?
Transmission?

Togavirus (+ssRNA)
Enveloped
Respiratory droplets

149

When is the Measles Mumps Rubella vaccine generally given?

12-14 months

booster before school

150

What is the reservoir for the MMR viruses?

Humans Only

151

What is by far the most important of the MMR diseases?

Measles

*because drop in vaccinations/loss of Herd Immunity

152

T/F
MMR are all ssRNA and enveloped

True

153

What white spots associated with Measles used to be diagnostic?

Koplik spots

154

What can Mumps viremia cause in the 1st trimester?

Spontaneous abortion

155

Why are ssRNA, enveloped, zoonotic infections on the rise?

Encroachment into reservoirs
Rapid transmission

156

Novel, vector borne viruses can either be _____ or _____.

Accidental
Dead End

*often very virulent

157

Why is zoonotic infection more common outside Hunter/Gatherer societies?

Diseases tend to Burn Out in Hunter/Gatherer

Large population/interaction

158

What is a novel virus from an insect?
From rodent?

Arbovirus
Robovirus

159

Arbovirus and Robovirus often cause what 2 conditions in humans?

Encephalitis
Hemorrhagic fevers

160

T/F
All vector borne viruses are enveloped and ssRNA

True

161

What type of pathology is induced by the Togaviruses (Rubella) and Flaviviruses (West Nile, Dengue)?

these are Arboviruses

Encephalatic: Rubella, West Nile

Hemmorhagic: Dengue

*Rubella exception, was once vector born Arbovirus but now its ours and is spread via respiratory aerosols

162

What is the reservoir for Hanta?
What kind of virus is it?

Desert Mous rat
Robovirus

*causes hemorrhagic fever (capillaries collapse)

163

How are roboviruses transmitted?

Fecally by rodents
(including bats, etc)

164

Why do vector-borne zoonotics often jump species?

ssRNA enveloped viruses have very high mutation rate

165

What do Prions cause?

Transmissible Spongiform Encephalopathies

166

Name 5 Prion diseases.

Kuru
Creutzfeldt-Jacob
Scrapie
BSE
Chronic wasting

167

T/F
Prions are larger than bacteria

False

168

Do Prions elicit an immune response?

No

169

Describe a PrP

Protease resistant
Hydrophobic glycoprotein
(aggregate)

170

What is an accumulation of PrP's in the CNS called?

Ameloid

171

Prions were once called...

Slow viruses

172

How are new Prions formed?
What is the disease progression?

Contact existing Prion causes folding
Prions > Ameloid > disease

173

If infected with smallpox, what were the chances of dying?
Terrible scarring?

1/3
1/3

174

What is the 1st and only infectious disease eliminated worldwide?

Smallpox

175

Smallpox:
nucleic acid type?
enveloped/naked?
transmission?

dsDNA
Complex (both enveloped and naked)
Respiratory droplets

176

The Middle Age technique of harvesting scabs at the end of a smallpox outbreak and applying it to cuts on the forehead after a time is called?

Variolation

177

What were the probable vectors for SARS and MERS?

Bats

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