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Step 1 Exam > Microbiology Virology - First Aid > Flashcards

Microbiology Virology - First Aid Flashcards

1
Q

Recombination

A

exchange of genes between 2 chromosomes by crossing over within regions of significant base sequence homology

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2
Q

Reassortment

A

when viruses with segmented genomes (influenza) exchange segments

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3
Q

Compementation

A

when 1 of 2 viruses that infect the cell has a mutation that results in a nonfunctional protein, the nonmutated virus “complements” the mutated one by making a functional protein that serves both viruses

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4
Q

Phenotypic mixing

A

simultaneous infection of a cell with 2 viruses; genome of virus A can be partially or completely coated with the surface proteins of virus B. Type B protein coat determines the tropism of the hybrid virus but the progeny have a type A coat encoded by the type A genetic material

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5
Q

Live attenuated viruses induce…

A

humoral and cell-mediated immunity but have reverted to virulence on occasion. No booster needed.

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6
Q

Killed/inactivated viruses induce….

A

only humoral immunity but are stable.

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7
Q

Live attenuated vaccines (6)

A
  1. smallpox
  2. yellow fever
  3. chickenpox
  4. Sabin polio virus
  5. MMR
  6. influenza (intranasal)
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8
Q

Killed vaccines (4)

A
  1. Rabies
  2. Influenza (injected)
  3. Salk Polio
  4. HAV
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9
Q

Recombinant vaccines (2)

A
  1. HBV

2. HPV

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10
Q

All DNA viruses are dsDNA except…

A

parvoviridae.

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11
Q

All DNA viruses are linear except…

A

papilloma, polyoma and hepadna (which are circular).

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12
Q

All RNA viruses are ssRNA excpet…

A

Reoviridae.

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13
Q

Positive stranded RNA viruses (7)

A 
Retrovirus
Togavirus 
Flavivirus
Coronavirus
Hepevirus
Calicivirus
Picornavirus
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14
Q

Purified nucleic acids of most dsDNA and + strand ssRNA viruses are…

A

infectious.

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15
Q

Naked nucleic acids of - strand ssRNA and dsRNA viruses are…

A

not infectious. They require polymerases conatined in the complete virion.

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16
Q

DNA viruses replicate in…

A

the nucleus, except poxvirus.

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17
Q

RNA viruses replicate in…

A

the cytoplasm, except influenza and retroviruses).

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18
Q

Nake viruses include:

A 
papillomavirus
adenovirus
parvovirus
polyomavirus
calicivirus
picornavirus
reovirus
hepevirus
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19
Q

Generally, viruses acqurie an envelope from…

A

plasma membrane when they exit a cell.

exception: herpesvirus acquires its envelope from the nuclear membrane

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20
Q

DNA viruses (7)

A

HHAPPPP(y)

  1. Hepadna
  2. Herpes
  3. Adeno
  4. Pox
  5. Parvo
  6. Papilloma
  7. Polyoma
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21
Q

DNA viruses general rules (4):

A
  1. are double stranded
  2. are linear
  3. are icosahedral
  4. replicate in the nuclus
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22
Q

The DNA virus that is not double stranded is…

A

parvovirus.

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23
Q

The DNA viruses that are not linear are…

A

papillomavirus/polyomavirus (circular, supercoiled) and hepadnavirus (circular, incomplete).

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24
Q

The DNA virus that is not icosahedral is…

A

poxvirus.

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25
Q

The DNA virus that does not replicate in the nucleus is…

A

poxvirus (it carries its own DNA-dependent RNA polymerase).

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26
Q

DNA viruses w/ an envelope

A
  1. herpesvirus
  2. hepadnavirus
  3. poxvirus
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27
Q

HBV features

A
  • hepadnavirus
  • hepatitis (acute or chronic)
  • vaccine (contains surface Ag)
  • not a retrovirus but has reverse transcriptase
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28
Q

Adenovirus medical importance

A
  • febrile pharyngitis (sore throat)
  • acute hemorrhagic cystitis
  • pneumonia
  • conjunctivitis (“pink eye”)
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29
Q

Parvovirus features (4)

A
  • B19 virus: aplastic crises in sickle cell
  • “slapped cheeks” rash in children: eythema infectiosum (fifth disease)
  • RBC destructino in fetus leads to hydrops fetalis and death
  • pure RBC aplasia/RA-like symptoms in adults
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30
Q

Papillomavirus features

A

HPV: warts (1,2,6,11)
CIN
Cervical cancer (16, 18)

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31
Q

Polyomavirus features

A

JC virus: PML in HIV

BK virus: transplant pts, commonly targets the kidney

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32
Q

Poxvirus features

A
  • smallpox (potential warfare)
  • cowpox (milkmaid blisters)
  • molluscum contagiosum (flesh-colored dome lesions with central umbilicated dimple)
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33
Q

HSV-1 diseases (4)

A
  • gingivostomatitis
  • keratoconjunctivitis
  • temporal lobe encephalitis
  • herpes labialsi
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34
Q

HSV-1 is latent in the…

A

trigeminal ganglia.

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35
Q

HSV-1 is transmitted via….

A

respiratory secretions and saliva.

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36
Q

HSV-2 diseaes

A
  • herpes genitalis

- neonatal herpes

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37
Q

HSV-2 is latent in the…

A

sacral ganglia.

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38
Q

HSV-2 is transmitted by…

A

respiratory secretions.

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39
Q

VZV diseases

A
  • chicken pox
  • shingles
  • encephalitis
  • pneumonia
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40
Q

VZV is latent in the…

A

dorsal root or trigeminal ganglia.

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41
Q

Most common complication of shingles is…

A

post-herpetic neuralgia.

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42
Q

VZV is transmitted by…

A

respiratory secretions.

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43
Q

EBV causes…

A

mononucleosis which is characterized by fever, hepatosplenomegaly, pharyngitis and lymphadenopathy (esp. posterior cervical nodes).

Transmitted by respiratory secretions/saliva. Commonly seen in teens/YAs.

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44
Q

EBV infects…

A

B cells. But the atypical lymphocytes seen on peripheral blood smear are not infected B cells but rather reactive cytotoxic T cells.

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45
Q

EBV is detected by…

A

positive monospot test - heterophile antibodies detected by agglutination of sheep/horse RBCs.

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46
Q

EBV is associated with…

A

Hodgkin lymphoma, endemic Burkitt lymphoma and nasopharyngeal carcinoma.

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47
Q

CMV causes…

A
  • congenital infection
  • mononucleosis (negative monospot)
  • pneumonia
  • retinitis
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48
Q

CMV infected cells have…

A

characteristic “owl eye” inclusions.

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49
Q

CMV is latent in…

A

mononuclear cells.

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50
Q

CMV is transmitted…

A

congenitally and by transfusion, sexual contact, saliva, urine and transplant.

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51
Q

HHV-6 causes….

A

Roseola: high fevers for several days that can cause seizures, followed by a diffuse macular rash.

(transmitted by saliva)

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52
Q

HHV-8 causes…

A

Kaposi sarcoma, a neoplasm of endothelial cells.

transmitted by sexual contact

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53
Q

Kaposi sarcoma is seen in…

A

HIV/AIDS and transplant pts.

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54
Q

Kaposi sarcoma presents with…

A

dark/violaceous flat and nodular skin lesions representing endothelial growths. It can also effect GI tract and lungs.

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55
Q

HSV Identification

A
  1. viral culture for skin/genitalia
  2. CSF PCR for herpes encephalitis
  3. Tzanck test
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56
Q

The Tzanck smear is a…

A

smear of opened skin vesicles (from genital herpes) to detect multinucleated giant cells.

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57
Q

HSV infected cells also have…

A

intranuclear Cowdry A inclusions.

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58
Q

Reovirus features

A

Envelope: No
RNA structure: DS linear, 10-12 segments
Capsid: icosahedral (double)

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59
Q

Reovirus disease

A
  1. coltivirus = colorado tick fever

2. rotavirus = #1 cause of fatal diarrhea in children

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60
Q

Picornavirus features

A

Envelope: No
RNA structure: SS + linear
Capsid: icosahedral

61
Q

Picornavirus disease

A
  1. Poliovirus - Salk/Sabin vaccines
  2. Echovirus = aseptic meningitis
  3. Rhinovirus = common cold
  4. Coxsackievirus = aseptic meningitis; herpangina; hand, foot and mouth disease; myocarditis, pericarditis
  5. HAV = acute viral hepatitis
62
Q

Hepevirus features

A

Envelope: No
RNA structure: SS+, linear
Capsid: Icosahedral

63
Q

Hepevirus disease

64
Q

Calicivirus features

A

Envelope: No
RNA structure: SS + linear
Capsid: Icosahedral

65
Q

Calicivirus disease

A

Norovirus = viral gastroenteritis

66
Q

Flaviviruses features

A

Envelope: Yes
RNA structure: SS + linear
Capsid: icosahedral

67
Q

Flaviviruses diseases

A
  1. HCV
  2. Yellow fever
  3. Dengue
  4. St. Louis encephalitis
  5. West Nile virus
68
Q

Togavirus features

A

Envelope: Yes
RNA structure: SS+, linear
Capsid: Icosahedral

69
Q

Togavirus diseases

A
  1. Rubella
  2. Eastern equine encephalitis
  3. Western equine encephalitis
70
Q

Retroviruses features

A

Envelope: Yes
RNA structure: SS+, linear
Capsid: Icosahedral (HTLV), complex and conical (HIV)

(have reverse transcriptase)

71
Q

Retrovirus diseaes

A
  1. HTLV = T-cell leukemia

2. HIV = AIDS

72
Q

Coronaviruses features

A

Envelope: Yes
RNA structure: SS+, linear
Capsid: helical

73
Q

Coronavirus disease

A

Coronavirus = “common cold” and SARS

74
Q

Orthomyxoviruses features

A

Envelope: Yes
RNA structure: SS+, linear
Capsid: helical

75
Q

Orthomyxovirus disease

A

influenza virus

76
Q

Paramyxovirus features

A

Envelope: Yes
RNA structure: SS-, linear, nonsegmented
Capsid: helical

77
Q

Paramyxovirus disease

A
  1. Paramyxovirus = croup
  2. RSV = broncholitis in babies
  3. Measles/Mumps
78
Q

Rhabdoviruses features

A

Envelope: Yes
RNA structure: SS-, linear
Capsid: Helical

79
Q

Rhabdovirus disease

80
Q

Filovirus features

A

Envelope: Yes
RNA structure: SS-, linear
Capsid: helical

81
Q

Filoviruses Diseases

A

Ebola/Marburg hemorrhagic fever

82
Q

Arenaviruses features

A

Envelope: Yes
RNA structure: SS-, circular, 2 segments
Capsid: Helical

83
Q

Arenaviruses diseases

A
  1. LCMV = lymphocytic choriomeningitis virus

2. Lassa fever encephalitis = spreads by mice

84
Q

Bunyaviruses features

A

Envelope: Yes
RNA structure: SS-, circular, 3 segments
Capsid: helical

85
Q

Bunyaviruses diseases

A
  1. California encephalitis
  2. Sandfly/Rift Valley fevers
  3. Crimean-Congo hemorrhagic fever
  4. Hantavirus = hemorrhagic fever, pneumonia
86
Q

Delta virus features

A

Envelope: Yes
RNA structure: SS-, circular
Capsid: uncertain

87
Q

Delta virus disease

A

HDV is a “defective” virus that requires HBV co-infection.

88
Q

Negative stranded viruses must…

A

transcribe negative strand to positive. The virion brings its own RNA-dependent RNA polymerase.

89
Q

Negative stranded viruses include (6):

A
  1. Arenaviruses
  2. Bunyaviruses
  3. Paramyxoviruses
  4. Orthomyxoviurses
  5. Filoviruses
  6. Rhabdoviruses

(Always Bring Polymerase Or Fail Replication)

90
Q

Segmented viruses are all…

A

RNA viruses:

  1. Bunyaviruses
  2. Orthomyxoviruses
  3. Arenaviruses
  4. Reoviruses

(BOAR)

91
Q

Picornaviruses have RNA that is translated into…

A

1 large polypeptide that is cleaved by proteases into functional viral proteins.

92
Q

All picornoviruses can casuse aseptic meningitis except…

A

rhinovirus and HAV.

93
Q

All picornaviruses are enteroviruses which means…

A

fecal-oral spread. Except for rhinovirus.

94
Q

Features of rhinovirus

A

-acid labile (destroyed by the stomach acid) and therefore does not infect GI like other picornaviruses

95
Q

Yellow fever virus is a flavivirus (also an arbovirus) transmitted by…

A

the Aedes mosquitoes. The virus has a monkey or human reservoir.

96
Q

Yellow fever virus symptoms include…

A

high fever, black vomitus and jaundice.

97
Q

Rotavirus is the major cause of…

A

acute diarrhea in the US during winter, esp. in day-cars, kindergartens. It causes villous destruction witha trophy leading to decreased absorption of Na+ and loss of K+.

98
Q

Influenza virus contains…

A

hemagglutinin (promotes viral entry) and neuraminidase (promotes progeny virion release) antigens. Has rapid genetic changes.

99
Q

Influenza virus puts pts at risk for…

A

fatal bacterial superinfection.

100
Q

Genetic shift/antigenic shifts casues…

A

pandemics. It is reassortment of the viral genome.

101
Q

During genetic shift, segmetns undergo…

A

high-frequency recombination, such as when human flu A virus recombines with swine flu A virus.

102
Q

Genetic drift causes…

A

epidemics. Minor changes are based on random mutation.

103
Q

Rubella causes…

A

fever, postauricular and other lymphadenopathy, arthralgias and fine rash. It is mild in children but serious congenitally.

104
Q

Congenital rubella findings include…

A

“blueberry muffin” appearance, indicative of extramedullary hematopoiesis.

105
Q

All paramyxoviruses contain…

A

F (fusion) protein, which causes respiratory epithelial cells to fuse and form multinucleated cells.

106
Q

Palivizumab is a…

A

monoclonal antibody against F protein that prevents pneumonia caused by RSV infection in premature infants.

107
Q

Measles characteristic signs are…

A

Koplik spots and descending maculopapular rash.

108
Q

Koplik spots are…

A

bright red spots with blue-white center on buccal mucosa that precede the measles rash by 1-2 days.

109
Q

Possible sequelae of Measles are…

A
  1. Subacute sclerosing panencephalitis (SSPE)
  2. Encephalitis
  3. Giant cell pneumonia
110
Q

SSPE symptoms

A

behavior changes, myoclonus, ataxia, ocular abnormalities, coma, increased Igs in CSF

111
Q

3 C’s of Measles

A

Cough
Coryza
Conjunctivitis

112
Q

When infected with the mesles virus, Vitamin A is used to…

A

prevent severe exfoliative dermatitis in malnourished children.

113
Q

Symptoms of Mumps

A
  1. Parotitis
  2. Orchitis
  3. aseptic Meningitis

-can cause sterility

114
Q

Rabies virus features

A
  • bullet-shaped

- Negri bodies (in purkinje cells and hippocampus)

115
Q

Postexposure treatment for rabies is…

A

wound cleansing and vaccination +/- rabies immune globulin.

116
Q

Rabies virus travels to…

A

the CNS by migrating in a retrograde fashion up nerve axons.

117
Q

Progression of rabies disease:

A

fever/malaise -> agitation/photophobia/hydrophobia -> paralysis/coma -> death

118
Q

Rabies virus in the US is most commonly from…

A

bat, raccoon and skunk bites.

119
Q

HAV features

A
  1. RNA picornavirus
  2. fecal-oral transmission
  3. no carrier
  4. short incubation (wks)
  5. no HCC risk
120
Q

HBV features

A
  1. DNA hepadnavirus
  2. parenteral, sexual, maternal-fetal transmission
  3. yes carrier
  4. long incubation
  5. HCC risk bc it integrates into host genome and acts as an oncogene
  6. HBV can cause carcinoma w/o cirrhosis!
121
Q

HCV features

A
  1. RNA flavivirus
  2. blood transmission (IVDU, transfusion)
  3. yes carrier
  4. long incubation
  5. HCC risk because of chronic inflammation
122
Q

HDV feature

A
  1. RNA delta virus
  2. parenteral, sexual, maternal-fetal transmission
  3. yes carrier
  4. superinfection (HDV after HBV) short incubation
  5. coinfection (HDV with HBV) long incubation
  6. HCC risk
123
Q

HEV features

A
  1. RNA hepevirus
  2. fecal-oral transmission
  3. no carrier
  4. short incubation
  5. no HCC risk
  6. high mortality in pregnant mothers
124
Q

In HBV, the DNA polymerase has both….

A

DNA and RNA dependent activities. UPon entry into the nucleus, the polymerase functions to complete the partial dsDNA. The host RNA polymerase transcribes mRNA from viral DNA to make viral proteins. The DNA polymerase then reverse transcribes viral RNA to DNA to make new viral particles.

125
Q

Anti-HAV (IgM)

A

IgM antibody to HAV; best test to detect active hep A

126
Q

Anti-HAV (IgG)

A

IgG antibody indicates prior HAV infection and/or prior vaccination; protects against reinfection

127
Q

HBsAg

A

Ag found on surface of HBV; indicates Hep B infection

128
Q

HBcAg

A

antigen associated with core of HBV (indicates actual infection rather than immunization)

129
Q

Anti-HBc

A

antibody to HBcAg; IgM = acute/recent infxn; IgG = prior exposure or chornic infection; positive during window period

130
Q

HBeAg

A

a second, different antigenic determinant in the HBV core. HBeAg indicates active viral replication and therefore high transmissibility.

131
Q

Anti-HBe

A

antibody to HBeAg; indicates low transmissibility

132
Q

ALT > AST indicates…

A

viral hepatitis.

133
Q

AST > ALT indicates…

A

alcoholic hepatitis.

134
Q

The 3 structural genes of HIV are…

A
  1. env (gp120 and gp41)
  2. gag (p24) - capsid protein
  3. pol (reverse transcriptase, aspartate protease, and integrase
135
Q

Env is formed from…

A

cleavage of gp160 to form envelope glycoproteins.

136
Q

gp120 is for…

A

attachement of HIV to host CD4+ T cell.

137
Q

gp41 is for…

A

fusion and entry.

138
Q

HIV dsDNa is able to…

A

integrate into host genome.

139
Q

The HIV virus binds…

A

CCR5 or CXCR4 co-receptor and CD4 on T cells. It binds CCR5 and CD4 on macrophages.

140
Q

Homozygous CCR5 mutation gives…

A

immunity to HIV. Heterozygous mutation causes a slower course.

141
Q

A presumptive diagnosis of HIV is made with…

A

ELISA (sensitive, high false-positive rate and low threshold).

142
Q

+ ELISA for HIV is then confirmed with…

A

Western blot assay (specific, high false-negative rate and high threshold).

143
Q

AIDS diagnosis is…

A

less than 200 CD4+ cells.

144
Q

ELISA/Western blot tests look for…

A

antibodies to viral proteins; these are often falsely negative in the first 1-2 months of HIV infection and falsely positive in babies born to infected mothers because anti-gp120 crosses the placenta.

145
Q

During the latent phase of HIV, the virus…

A

replicates in LNs.

146
Q

Prion diseases are caused by…

A

the conversion of a normal (predominantly alpha-helical) prion protein (PrPc) to a beta-pleated sheet form (PrPsc) which is transmissible.

147
Q

PrPsc resists…

A

protease degradation and facilitates the conversion of still more PrPc to PrPsc.

148
Q

Accumulation of PrPsc results in…

A

spongiform encephalopathy and dementia, ataxia and death.

149
Q

Types of Prion Disease

A
  1. Creutzfeldt-Jacob disease (sporadic, rapidly progressive dementia)
  2. Gerstmann (inherited)
  3. Kuru (acquired)

Step 1 Exam (32 decks)

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