Intro Flashcards
(69 cards)
1
Q
Fundamental properties
A
- filterable agents
- RNA or DNA genome
- obligate intracellular parasite
2
Q
Classification criteria
A
- Nature of nucleic acid
- Symmetry of the capsid
- Envelope (+/-)
- Size
3
Q
size range
A
20nm - 300nm
4
Q
smallest virus (DNA/RNA)
A
~25 nm
DNA Parvovirus
RNA Picornavirus
5
Q
largest virus
A
DNA poxvirus ~300 nm
RNA paramyxovirus
6
Q
DNA Viruses, Genome
A
Parvo, SS, linear Hepadna, DS, circular Papilloma, Ds, circular Polyoma, DS, circular Adeno, DS, linear Herpes, DS, linear Pox, DS, linear
7
Q
RNA Viruses with
SS + Genome
A
Picorna, SS, + Calici, SS, + Astro, SS, + Toga, SS, + Flavi, SS, + ----- Retro SS + (two identical
8
Q
RNA Viruses with
SS - Genome
A
Rhabdo, SS, - Paramyxo, SS, - Orthomyxo, SS - Filo, SS - Arena, SS - Bunya, SS -
9
Q
RNA Virus with
DS Genome
A
Reo, DS +/-
10
Q
Capsid structure
A
Symmetry - icosahedral or helical
11
Q
capsid definition
A
protein coat surrounding nucleic acid
12
Q
capsomer definition
A
repeating protein subunits making up capsid
13
Q
protomer definition
A
polypeptide chains that make up the capsomers
14
Q
helical capsids are composed of _____
A
helical capsids are composed of multiple copies of a single kind of protein subunit in a close-packed helix
15
Q
Icosahedral capsid symmetry (faces, arrangement)
A
20 triangular faces
5:3:2 symmetry (referring to folds)
16
Q
virion definition
A
the complete virus particle
17
Q
nucleocapsid
A
capsid proteins associated with the viral nucleic acid
18
Q
nucleoprotein
A
proteins associated with the viral nucleic acid
19
Q
viral envelope composed of…
A
lipids, proteins, glycoproteins
20
Q
what are spikes?
A
virus encoded envelope proteins that serve as viral attachement proteins
21
Q
What kind of capsid? Adenovirus Herpes Influenza HIV Bacteriophage
A
Adenovirus - naked iocosahedral
Herpes - enveloped icosahedral
Influenza - enveloped helical
HIV - enveloped icosahedral
22
Q
What are prions
A
abnormal, pathogenic, transmissible agents that are able to induce abnormal folding of normal cellular proteins
23
Q
Prion diseases
A
…usually rapidly progressive and ALWAYS fatal.
- CJD
- vCJD (variant)
- Gerstmann-Stausler-Scheinker
- Fatal Familial Insomnia
- Kuru
24
Q
CJD
A
Creutzfeldt - Jacob
Spontaneous transformation of normal proteins into abnormal prions.
Risk of transmission with improperly sterilized instruments.
25
vCJD
variant of CJD
| Bovin spongiform encephelopathy (BSE)
26
How do viruses gain entry into host cells
1) Fusion with cell membrane
• At cell membrane
• In an endosome
2) Receptor-Mediated endocytosis
27
Where are viral receptors found?
- they're usually normal cell surface components (CD4 to gp120)
- generally requires coreceptor (CCR5/CXCR4 to gp41)
28
describe general model of replication
- attachment
- penetration
- uncoating
- replication
- transcription/translation
- assembly/maturation
- release
29
How are RNA virus genomes synthesized???
RNA viruses genomes encode their own Polymerase to create a strand of mRNA to be read by cellular machinery...
viral polymerase creates RNA from RNA
retroviruses are the exception (vRNA -> DNA, inserted into host)
30
(+) vs (-) RNA polymerase use
(+) RNA viral genome can be directly transcribed by cellular machinery into viral proteins... one of these is viral polymerase
(-) RNA viral genome must be converted to (+) strand of RNA before transcription... viral polymerase is included in the viral particle.
31
RNA virus replication generally occurs in _____. DNA virus replication generally occurs in ____, which allows for _____.
- the cytoplasm (except retrovirus and influenza)
- the nucleus (except poxvirus)
- insertion into genome and host cell transformation
32
DNA virus life cycle
```
Attachment
Entry
Uncoating
MOVE TO NUCLEUS
GENE EXPRESSION (staged)
Replication
Assembly
Release (bud with nuclear membrane envelope)
```
33
Viral release modes (naked vs enveloped)
Naked - lysis of cell (death)
| Enveloped - budding through cell membrane (may spare cell)
34
AIDS caused by
HIV-1
35
Hepatitis caused by
HAV-HEV
CMV
EBV
36
Cancer
```
HPV
HBV, HCV
EBV
HHV-8
HTLV-1
```
37
Encephalitis
```
HSV
togaviruses
flaviviruses
rabies
picornaviruses
```
38
Meningitis
enteroviruses
mumps
HSV-2
VZV
39
GI Tract disease
rotaviruses
caliciviruses
adenoviruses (40, 41)
40
Common cold
rhinoviruses
coronaviruses
adenoviruses
41
Lower respiratory tract infections
influenza
parainfluenza
ReSV
adenoviruses
42
Congenital & neonatal infections
```
CMV
parvovirus B19
rubella
HSV
HIV
lymphocytic choriomeningitis
```
43
Respiratory transmission
localized: influenza, common cold (rhino, corona, adeno)
disseminated: varicella-zoster, measles
44
Fecal-oral transmission
| Localized: 4
Localized: 4
| Norovirus, Rotovirus, Astrovirus, Adenovirus
45
Fecal-oral transmission Second site
```
Second site:
Picorna family
-Enteroviruses
-Polio
-Coxsackie
-Echovirus
-Enterovirus
-Hepatitis A
```
Hepatitis E
46
Enterovirus secondary viremia - Meninges
Meninges: Echo, Polio, Coxsackie A
47
Enterovirus secondary viremia - liver
Liver: Hep-A
48
Enterovirus secondary viremia - Skin
Skin: Echo, Hep-A
49
Enterovirus secondary viremia - muscle
Muscle: Echo, Cox A/B
50
Enterovirus secondary viremia - Brain
Brain: Polio, Coxsackie
51
Norovirus is the frequent cause of acute disease outbreaks on ____, and in ____/____
cruise ships
daycare centers / nursing homes
52
Rotavirus causes 50% of ___ ___ in infants and children under 2 yrs
acute gastroenteritis
53
Chronic viral diseases
HIV
Hep-B
Hep-C
HTLV-1
54
Emerging viral infections caused by viruses that ___, ___, ___
1) continue to find vulnerable pops
2) continue to evolve
3) introduced from other species (zoonoses)
55
What's a dang quasispecies?
How does it happen?
Example?
Heterogenous group of sequences clustering around a consensus.
RNA polymerase lacks proofreading allowing for many mutation opportunities
HIV and influenza
56
Zoonoses types and their vectors
Arbovirus (arthropod)
Rabies (bats, coons, dogs)
Hantavirus (deer mouse)
Pox virus
57
Best tool for controlling viruses?
Prophylaxis
- vaccines
- universal precautions
- education**
58
Lytic vs Persistent infections
Lytic kill the cell through various mechanisms
```
Persistent do not cause cell death... may be:
chronic
latent
recurrent
transforming
```
59
Syncytia is ___...
| ... for example _____
a mass of cytoplasm containing several nuclei
HIV, herpesvirus, Respiratory Syncytial Virus (a paramyxovirus)
60
How is a virus detected after cultivation?
Cytopathic effects
Immunofluorescence
Hemadsorption / hemagglutination
61
Cytopathic effects include:
Cytopathic effects
- rounding / detachment
- syncytia
- shrinkage
- increased refractility
- aggregation
- lysis
62
Describe hemagglutination
example?
Many viral proteins bind to erythrocytes, and causes clumping
Flu is an example .. H in H1N1 means hemagglutination
63
Criteria for diagnosing a primary infection through serology
- at least 4x increase in titer of IgG or total antibody between acute and convalescent sera
- Presence of IgM
- Seroconversion
- a SINGLE high titer of IgG, though very unreliable
*** usefulness depends on individual virus
64
Serology works best / worst for:
Best: rubella / hep-a, because symptoms coincide with Ab titers
Worst: resp. / diarrheal, because clinical presentation occurs before Ab titers
65
Serology and HIV
HIV produces clinical disease years after seroconversion... presence of Ab is enough to make definitive diagnosis
66
Diagnosis through direct examination is made by viewing
inclusion bodies in histological slide
67
Detection of viral nucleic acid and antigens is used for____
screening for blood transfusion
68
Detection of viral antigens is done with ___
ELISA
| PCR
69
Viral nucleic acid is detected using
Gene chip (Virochip)
