Viruses Part I Flashcards
Chapter 13 (116 cards)
1
Q
Define Viruses
A
Latin for poison
2
Q
Characteristics of Viruses (7)
A
- obligate intracellular parasites
- very small, filterable
- contain one type of nucleic acid (either DNA or RNA)
- Nucleic acid surrounded by a protein coat (capsid)
- Have little enzymes of their own
- May have lipid envelopes
- Many have a range of host cells able to infect
3
Q
What is the virion?
A
complete infectious particle
4
Q
Do viruses have a plasma membrane?
A
No
5
Q
Do viruses replicate through binary fission?
A
No
6
Q
Can viruses pass through bacteriological filters?
A
Yes
7
Q
Do viruses possess both RNA and DNA
A
No, only one of them
8
Q
Do viruses have an ATP-generating metabolism?
A
No
9
Q
Do viruses have ribosomes?
A
No
10
Q
Are viruses sensitive to antibiotics?
A
No
11
Q
Are viruses sensitive to interferon?
A
Yes
12
Q
What is the structure of a virion?
A
Nucleic acid surrounded by capsid +/- lipid envelope.
13
Q
What do we classify viruses by? (3)
A
- nucleic acid content (DNA or RNA)
- capsid
- envelope
14
Q
Describe nucleic acids
A
DNA or RNA (can be single stranded or double stranded, linear or circular, continuous or segmented)
15
Q
single stranded RNA genomes…
A
have a polarity (+ or -)
16
Q
+ RNA…
A
can go in the cell and DIRECTLY function as RNA
17
Q
(-) RNA…
A
must first be TRANSCRIBED into +RNA strand which then serves as the mRNA
18
Q
Retrovirus
A
RNA transcribed into DNA inside the host
19
Q
What is a capsid?
A
protein coat surrounding the nucleic acid
20
Q
What are the units that make up capsids called?
A
capsomers
21
Q
What are the 3 capsid shapes?
A
- helical
- polyhedral
- complex
22
Q
Describe Helical Symmetry (regarding capsids)
A
- looks like a long rod
- multiple copies of the same protein wrapped in a helix
- nucleic acid surrounded by a hollow, helical, cylindrical capsid
23
Q
Examples of viruses with helical symmetry (1):
A
- Tobacco Mosaic Virus (TMV)
24
Q
Describe Polyhedral Symmetry (regarding capsids)
A
- many sides
- ICOSAHEDRAL (20 sides, 12 corners)
- Each side = equilateral triangle
25
Examples of viruses with polyhedral symmetry (3):
- Polio Virus
- Adenovirus
- Herpes Virus
26
Describe Complex Symmetry:
- complicated structures
- somewhat asymmetrical
27
Examples of viruses with complex symmetry (2):
- bacteriophage viruses (have capsid, tail, + sheath)
- pox virus (no capsid but several coats around nucleic acid)
28
What is an envelope?
It surrounds the nucleocapsid of some animal viruses.
29
What are virus envelopes made of?
They are made up of host cell lipids (lipid bilayer) and viral proteins
30
What do virus envelopes sometimes have?
viral glycoproteins called peplomers or spikes
31
What are viral glycoproteins called?
Peplomers or spikes
32
What are viral glycoproteins used for?
Attachment to host cell
33
What do virus envelopes do? (3)
- may help virus get away from the cell
- keeps segments of segmented genome together
- antigenic: host immune system can mount an attack
34
Taxonomy of Viruses (at first)
- plant viruses
- animal viruses
- bacteriophage
35
Taxonomy of Viruses (then)
- respiratory diseases
- enteric viruses
36
Taxonomy of Viruses (now)
- nucleic acid type (DNA, RNA)
- replication strategy
morphology
37
Describe Parvoviridae (3)
- single stranded DNA
- icosahedral
- naked
38
Examples of Parvoviridae (4)
- Gastroenteritis
- fetal death
- fifth disease
- human parvovirus B19
39
Describe Adenoviridae (3)
- double stranded DNA
- icosahedral
- naked
40
Examples of Adenoviridae (1)
- Respiratory diseases
41
Describe Papovaviridae (3)
- double stranded DNA
- icosahedral
- naked
42
What does the pa-po-va in papovaviridae stand for?
- Pa (papilloma): warts
- Po (polyoma): tumors
- Va (vacuolating): causes vacuoles in host cell
43
Examples of Papovaviridae (1)
- HPV (human papilloma virus)
44
Describe HPV (human papilloma virus) (2)
- more than 60 types
- benign warts, plantar warts, laryngeal warts, cervical warts
45
Describe Poxviridae (4)
- double stranded DNA
- complex
- enveloped
- largest of all the viruses
46
Examples of Poxviridae (2)
- smallpox virus
- cowpox virus
47
What is the only disease eradicated through vaccination efforts?
- smallpox virus
48
Describe Hepadnaviridae (5)
- circular
- double stranded
- icosahedral
- enveloped
- unusual replication cycle
49
Examples of Hepadnaviridae (1)
- Hepatitis B Virus
50
Describe Herpesviridae (5)
- double stranded
- icosahedral
- enveloped
- very large viruses, become latent
- ubiquitous in animals
51
Examples of Herpesviridae (8)
- HHV-1
- HHV-2
- HHV-3
- HHV-4
- HHV-5
- HHV-6
- HHV-7
- HHV-8
52
Describe HHV-1 and HHV-2
- Simplexvirus: cause cold sores and genital herpes
53
Describe HHV-3
- Varicellovirus: causes chickenpox and shingles
54
Describe HHV-4
- Lymphocryptovirus: EBV (Epstein Barr Virus) causes mononucleosis
55
Describe HHV-5
- Cytomegalovirus
56
Describe HHV-6 and HHV-7
- Roseolovirus
57
Describe HHV-8
- Rhadinovirus: causes Kaposi's sarcoma
58
What percent of the population is infected with HHV-1?
~85%
59
How is herpes simplex 1 transmitted?
Transmitted by oral or respiratory tract
60
What does HHV-1 cause?
Cold sores
61
What causes HHV-1 lesions to recur? (5)
- stress
- sunlight
- menstruation
- fever
- hormonal changes
62
Where is the HHV-1 dormant?
Trigeminal nerve ganglion
63
What does HHV-2 cause?
Genital herpes
64
How is HHV-2 transmitted?
Sexual transmission
65
Where is the HHV-2 dormant?
Sacral nerve ganglion
66
Treatment for Genital Herpes
Acyclovir: improves primary lesions and reduces recurrences
67
Is their a cure for genital herpes?
No
68
What are the possible effects of neonatal herpes (3)
- abortion
- mental retardation
- defective sight and hearing
69
How would an infant acquire herpes during birth?
If the mother has blisters at time of delivery, it transfers to the baby.
70
How is HSV-2 given to an infant? (2)
- crosses the placenta and infects the fetus
- mother has herpes blisters at time of the delivery
71
Describe Picornaviridae (4)
- (+) RNA
- icosahedral
- naked
- very small (pico)
72
Examples of Picornaviridae (4)
- polio virus: polio
- coxsackieviruses
- enteroviruses (hepatitis A virus, HAV)
- rhinoviruses: common cold
73
Describe Togaviridae (4)
- (+) RNA
- icosahedral
- enveloped (toga)
- transmitted by arthropods (mosquitos)
74
Examples of Togaviridae (2)
- Arboviruses (encephalitis viruses)
- Rubiviruses (rubella)
75
Describe Coronaviridae (2)
- (+) RNA
- icosahedral
76
Examples of Coronaviridae (4)
- Common cold
- SARS-CoV
- MERS-CoV
- SARS-CoV2 (COVID-19)
77
Where did COVID-19 originate from?
China, Wuhan province
78
What type of virus is COVID-19 and what did it most likely originate from? (2)
- zoonotic virus (cross species transmission)
- bats
79
How is COVID-19 spread? (3)
- person to person via fomites (sharing cups, eating utensils, etc.)
- touching, kissing, shaking hands
- droplets (possible air transmission in short distances)
80
What are the symptoms of COVID-19? (11)
- fever or chills
- cough
- difficulty breathing
- fatigue
- body aches
- headache
- loss of taste or smell
- sore throat
- congestion
- nausea/vomiting
- diarrhea
81
What are current (experimental) treatments available for COVID-19? (2)
- monoclonal antibody infusion
- oral pill (molnupiravir)
82
What are the known vaccines for COVID-19? (6)
- Pfizer (m-RNA)
- Moderna (m-RNA)
- Johnson and Johnson (viral vector)
- Astra Zeneca (viral vector)
- Chinese Vaccines (killed virus)
- Russia, Sputnik (viral vector)
83
Describe Orthomyxoviridae (4)
- segmented (8 helical nucleocapsids)
- single stranded (-) RNA
- helical
- enveloped
84
Examples of Orthomyxoviridae (3)
Influenza Viruses:
- Influenza Virus A (can infect swine, birds, and horses)
- Influenza Virus B
- Influenza Virus C
85
(T/F) H3N2 mutates more rapidly than H1N1
True, they are deadlier and more virulent as well
86
What are peplomers? (2)
- protein spikes
- antigenic
87
Types of peplomers (2)
- H: hemagglutinin, attachment (18 different)
- N: neuraminidasec release from host cell (11 different)
88
What are the two types of influenza antigenic variation?
- antigenic drift
- antigenic shift
89
Describe Antigenic Drift (2)
- small point mutations (affect H and N)
- new subtype is slightly different than parent
90
Describe Antigenic Shift (3)
- less common, only occurs with influenza A
- sudden and major change (H and/or N antigens)
- creates a new strain
91
Example of an Antigenic Shift
H3N2 to H1N1 (recombination occurring when 2 strains of viruses infect the same cell)
92
What is the best mixing vessel for viruses?
Pigs (Swine)
93
What is the pathway of viruses (spread)?
Bird to pig to human
94
What types of Influenza was the Spanish Flu?
H1N1
95
Characteristics of the Spanish Flu
- higher than normal activation of genes associated with T Cells and Macrophages
- higher than normal activation of genes related to tissue injury, oxidative damage, and apoptosis
- induces a cytokine storm
96
How is influenza spread? (2)
- droplets
- hands
97
Where does influenza attach to in cells?
H glycoprotein to sialic acid receptors on cells
98
What symptoms do cytokines cause? (6)
- chills
- fever
- malaise
- muscle aches
- runny nose
- cough
99
Why would someone die from influenza?
Bacterial superinfections (S. aureus, H. influenzae, Streptococcus pneumoniae)
- diagnose through rapid agglutination tests of throat swabs
100
What are treatments for influenza? (2)
- Tamiflu (inhibits viral release from cells)
- Xofluza (inhibits polymerase acidic endonuclease)
101
What is the best way to prevent influenza?
Through vaccination
102
How are vaccines grown?
- killed injected influenza is grown in eggs or in cell culture
103
Describe Flumist
A live attenuated viral vaccine given intranasally.
104
Describe Flaviviridae (3)
- (+) RNA
- polyhedral
- enveloped
105
Examples of Flaviviridae (2)
- flaviviruses (includes yellow fever)
- hepatitis C virus (HCV)
106
Describe Retroviridae (5)
- diploid
- single stranded + RNA
- icosahedral
- enveloped
- reverse transcriptase***
107
Examples of Retroviridae (3)
- RNA Tumor Viruses (oncoviruses)
- Leukemia Viruses (HTLV-1)
- Immunodeficiency Viruses (HIV)
108
Describe Paramyxoviridae (3)
- (-) RNA
- helical
- enveloped
109
Examples of Paramyxoviridae (3)
- Paramyxovirus (parainfluenza)
- Mumps Virus
- Rubeola Virus (measles)
110
Describe Rhabdoviridae "rod" (5)
- (-) RNA
- helical
- enveloped
- shaped like bullets with spiked envelope
- rod with one flat and one curved end
111
Examples of Rhabdoviridae (1)
- Rabies Virus
112
Describe Filoviridae (4)
- (-) RNA
- helical
- enveloped
- long, thread-like
113
Examples of Filoviridae (2)
- Ebola Virus
- Marburg Agent
114
Describe Reoviridae (4)
- segmented
- double stranded RNA
- icosahedral
- naked
115
What does R.E.O. stand for in Reoviridae?
- R = Respiratory Diseases
- E = Enteric Diseases
- O = Orphan (not associated with any disease)
116
Examples of Reoviridae (2)
- Rota Virus (severe diarrhea in young children)
- Colorado Tick Fever Virus
