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Medical Microbiology > L 26 - 30 > Flashcards

L 26 - 30 Flashcards

(102 cards)

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1
Q

True or False: Viruses are obligate intracellular parasites that use host cell translation machinery

A

True

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2
Q

Viral replication yields ___, which are the vehicle for transmission to next host cell

A

Virion

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3
Q

True or False: Viral genome is RNA only and are packaged inside particle

A

False - while genomes of viruses are packaged inside particle, the genome itself can be RNA/DNA

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4
Q

DNA viruses either use host ___ or encode their own

A

polymerases

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5
Q

True or False: (+) SS RNA viruses makes mRNA while – transcription/translation–(-) SS RNA makes polypeptides only

A

False

(+) SS RNA
- polyproteins
- translation

(-) SS RNA
- mRNA
- proteins

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6
Q

Which of the following must encode RNA-dependent polyermase?
A. (+) SS RNA
B. (-) SS RNA

A

B. (-) SS RNA

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7
Q

_____: (+) sense RNA viruses that require DNA intermediate for replication (RNA to DNA to RNA)
A. Hep B Virus
B. Retrovirus
C. Hep C Virus

A

Retroviruses

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8
Q

_____: A gapped DNA genome; full-length but nicked (+) strand and partial (-) strand
A. Hep B Virus
B. Retrovirus
C. Hep C Virus

A

A. Hep B Virus

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9
Q

What are four mechanisms used to get many proteins out of small genomes?

A
  1. polyprotein synthesis
  2. leaky scanning
    - ribosomal binding sites
    - inefficient start codon
  3. reinitiation
    - many upstream ORF
  4. many ribosome binding sites
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10
Q

____: secondary structure that is important for efficient recognition of mRNA and translation

____: promotes packing of genome for assemebly into developing virions

A

IRES; packaging signals

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11
Q

True or False: Capsids can be Icosahedral or Helical

A

True

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12
Q

All humans with helical symmetry are ____

No DNA viruses have been discovered that are helical

A

enveloped

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13
Q

True or False: Enveloped viral envelopes take part of the plasma membrane with them, whereas non-enveloped leave cell without any host plasma membrane

A

True

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14
Q

Why are enveloped viruses wimpy?

A
  1. Envelopes break down fast outside of host
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15
Q

Which are harder to destroy: enveloped or non-enveloped viruses?

A

Non-enveloped – because they have stable capsid protein

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16
Q

____: Occurs after attachment; time between entry and production of new virus

____: Number of viruses undergoes exponential growth

A. Eclipse; Exponential
B. Exponential; Eclipse

A

A. Eclipse; Exponential

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17
Q

Three steps of viral infection?

A
  1. Attach, penetrate, and uncoat
  2. Transcription, translation, and replication
  3. Viral assembly, exit, and maturation
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18
Q

What are the three mechanisms for viral entry? Which is NOT pH dependent?

A

1) Uncoating at plasma membrane
- pH Independent
- No endosomal acidification

2) Uncoating within endosomes

3) Uncoating at nuclear membrane

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19
Q

A viral genome may or may not encode its own polymerase but no virus encodes its own ___ machinery. Thus, all viruses depend on host to make proteins

A

transcriptional

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20
Q

Which three places can viral assembly occur?

A
  1. Nucleus
    - Herpes
  2. Cytoplasm
    - Vacina
  3. Cell membrane
    - Retrovirus
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21
Q

How do non-enveloped viruses leave the cell?

How do enveloped viruses leave the cell?

A

Non-enveloped = Lysis

Enveloped = Budding

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22
Q

Which type of infection involves a non-permissive cell and a defective infecting virus? Ultimately, the host cell dies before virus is even made (no viral progeny made!)?

A. Persistent Infection
B. Abortive Infection
C. Latent Infection

A

B. Abortive Infection

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23
Q

Which type of infection allows viruses to constantly be made, with host cell maintaining normal function?

A. Persistent Infection
B. Abortive Infection
C. Latent Infection

A

A. Persistent Infection

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24
Q

True or False: In a latent infection, host cell survives and no virus is made, but some viral proteins are. Can be reactivated to make virus!

A

True

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25
True or False: In oncogenic transformation, cells are immortalized
True
26
Abortive and Latent infections have ___ effect while___ infections cause senescence and cytolytic infections cause cell death
Abortive/Latent: no Persistent: senescence Cytolytic: cell death
27
What do you need to make a productive infection?
1. Enough virus 2. Permissive cells at infection site 3. Absent local host defenses
28
Lymphatic spread is an example of ___ infection
systemic
29
How can viruses disseminate throughout body???
1) Lymphatics 2) Blood 3) Neurally
30
True or False: Virus must be grown in vitro
False - in cell culture
31
Three tests for detecting viruses?
1) Direct - examined? 2) Indirect - Specimen is incubated in presence of cells that allow for growth 3) Serology - Ab titer against antigen
32
Electron/Light microscopy, Antigen detection, and molecular techniques are example of ___ virus examination
direct
33
Two steps to indirectly examining virus?
Step 1: cell culture - primary cells (normal) - semi-cont (embryonic) - conti (immortal) Step 2: presence of virus detected by - tzanck smear - cytopathic effect - haemadsorption
34
True or False: Serology is used to diagnose a primary infection
True
35
Which two are acute infections? A. HPV and HIV B. HPV and Measles C. Flu and Measles
C. Flu and Measles
36
True or False: HIV can either be a persistent/chronic infection or a slow, viral infection
True
37
True or False: HPV is a tumor related virus
True
38
Which two serotypes are important in influenza? A. A and B B. B and C C. C and D
A. A and B
39
True or False: Orthomyxovirus can cause the flus - it is ENVELOPED, SEGMENTED, (-) ssRNA that is helical
True
40
Serotypes in influenza are based on M_ and M_
M1 (nucleocapsid protein) M2 (membrane protein)
41
All three influenza viruses have both ___ (used to attach to human cells) and ___ peplomers
Hemagluttinin - attach to human cells Neuroaminidase - penetration and release from infected human cells
42
Which subtype of Influenza are based on antigenic variability of the envelop spikes? A. Subtype A B. Subtype B
A. Subtype A
43
The influenza virus is capable of which two antigenic variation?
Antigenic drift - point mutations in H/N glycoprotein genes - A and B types Antigenic shift - major change due to genetic recombination of RNA segments - new virus (change in hemagluttinin) - only occurs in A !!!! - could result in no herd immunity
44
What are three ways that Influenza A virus gets antigenic variation?
1. Mutation (shift/drift) 2. Reassortment (shift) 3. Recomb (shift)
45
High fever is clinical manifestation of ___
flu
46
Most common complication in influenza?
OM
47
Two types of pneumonia that can arise from flu?
1 influenza pneumo 2 bacterial pneumonia
48
How do you treat viral release in influenza?
NA inhibitor
49
True or False: Both Oseltamivir and Zanamivir are NA inhibitors that treat Flu A and B
True
50
Three types of flu vax?
1. Killed - inactivate A. Eggs B. Multivalent 2. Split-virus (subvirion) 3. Live/Attenuated A. Nasal
51
_____: acute, highly contagious disease characterized by fever, maculopapular rash, and post-infection sequlae. Caused by: paramyxovirus (ssRNA)
Measles
52
True or False: Humans are only host of measles
True
53
Koplik spots during the prodromal phase and maculopapular rash (cytotoxic T cells) suggest ____
Measles
54
True or False: OM is the most common complication of measles
True
55
IgM via serology and lesions on oral mucus membrane suggests ___
measles
56
MMRV is a vaccine against:
measles
57
___ is an enveloped retrovirus, ss RNA genome that uses RT, Integrase, and Proteases A. HPV B. HIV C. Measles
B. HIV
58
____ and ____ are subsequently cleaved shortly after budding by HIV-1 protease into surface glyoproteins and mature Gag proteins, respectively A. gp 160; Pr55Gag B. Pr55Gag; gp 160
A. gp 160; Pr55Gag
59
True or False: Humans are sole reservoir and host for HIV
True
60
For viral entry of HIV into the cell HIV ___ binds to CD4, then undergoes conformational change that allows it to bind to two co-receptors (CCR5 and CXCR4) Once gp120 binds to both CD4 and chemokine-R, gp41 undergoes conformational change
gp120
61
During primary infection, what is the predominant HIV strain (uses CCR5 co-receptor)
M tropic HIV
62
As HIV infection proceeds, there's a switch in viral phenotype that gives rise to ____ HIV (uses CXCR4 co-receptor) A. M tropic B. T tropic
B. T tropic
63
CCR5 is found on ____ R5 strains while CSCR4 is found on ____ X4 strains
M trophic; T trophic
64
Koilocytotic cells suggest __
HPV
65
In HPV, viral regulation of ___ is lost. Break occurs in ___ region.
E6/7; E2
66
In HPV, when Tb is hyperphosphorylated (E2F) transcription is ____
repressed
67
In HPV, L1 and L2 are the major and minor ___ proteins E6 and 7 are ___ while E1 is a viral helicase that recruits DNAP
capsid oncogenes
68
True or False: In HPV, late genes make up the capsid while early genes are important for hijacking cellular functions
True
69
True or False: CMI is required to control HPV
True
70
Cervical papillomas and Condyloma acuminatum are associated with ___
HPV
71
What is the most prevalent STD?
HPV
72
In HPV, E6 binds to ___ while E7 binds to ___
E6 = p53 E7 = Rb
73
Opthalmic zoster involves CN __
V
74
Unilateral or vesicular rashes suggests ___
shingles
75
Severe pain, burning, itching, rash (asymmetrical maculopapular or vesicular crusting that following a single thoracic dermatome/CN) suggests which condition?
Herpes zoster shingles
76
Chickenpox is clinical manifestation of ___. Often associated with skin lesions on back and trunk, which can spread to the face.
Varicella
77
True or False: In chickenpox, prodromal symptoms are often absent in the young
True
78
VZV, an enveloped, dsDNA (thymidine kinase) can cause ____. It is neurotrophic, therefore can become latent.
chickenpox
79
True or False: Chicken pox is a highly contagious, generalized lesions while Shingles is recrudescence of same virus
True
80
Acyclovir can caused chain termination by acting on ____, not a cure however.
TK
81
What can cause transition from HSV latency to virus production?
Increased in ICPO HSV gene expression, decreased in ICP4
82
Which four factors promote transistion in HSV?
1. Repression 2. Sensory neurons 3. LAT expression 4. Inhibition of viral replication
83
Which phase of HSV-1 active infection is associated with viral capsid assemble/progeny DNA encapsidation (nucleus). Virions then egress from the cell. A. Phase 1 B. Phase 2 C. Phase 3 D. Phase 4
D. Phase 4
84
Which phase of HSV-1 is associated with DNA replication, expression of late genes, and translation of late genes
Phase 3
85
Which phase of HSV activation is associated with initiation of HSV genome replication?
Phase 2
86
True or False: In Phase 2 of HSV-1 infection, early gene expression and IE protein transactivation is required for DNA replication
True
87
In phase 1 of HSV-1 active infection, immediate early genes are expressed using __ ___ ___
Host RNA Polymerase
88
What induces phase 2 of HSV-1 active infection?
IE RNA transcripts are translated. IE proteins induce stage 2!
89
Which HSV gene is involved in DNA replication?
Early gene
90
True or False: Late proteins are initiated after start of DNA synthesis in HSV
True
91
Three hallmarks of latency?
1. decreased gene expression 2. reduced recognition by IS 3. persistance of intact viral genome 4. mechanism to re-enter productive phase of life cycle
92
How do HAART drugs work against HIV?
Increase T cell count Reduce vira load Note: latent virus in T cells remain, despite therapy
93
Integrase inhibitors can be use against which condition? How do they work?
HIV - decrease HIV viral repication when used in combo with HAART
94
How do Fuzeon and Selzentry inhibit fusion and early entry in HIV?
Fuzeon = blocks gp41 Selzentry = blocks CCR5
95
How do protease inhibitor work in HIV?
Block protease activity and viral maturation; binds irreversibly
96
True or False: In HIV treatment, RTI cause viral DNA chain termination
True
97
True or False: To treat HIV, NNRI's block RT but do not incorporate into growing DNA chain
True
98
Historically, HAART treatment for HIV has been 2 __ and a __
2 RTI + PI
99
Analysis of presence of p24 suggests ___
HIV
100
True or False: In HIV infection, neutralizing Ab are usually directed against gp120 while Cytotoxic T cells kill HIV infected cells, but also helper cells
True
101
In HIV, low viral burden means __ disease progression while __ viral burden means ___ disease progression
slow faster
102
What are two mechanisms by which HIV reduces CD4+ T cells?
1) Direct - Via CD4+ T cells 2) Indirect - Autoimmune rx - HIV specific CD8 T cells that kill helper cells

Medical Microbiology (31 decks)

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