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Biol121- Impact Of Microbes > Important Key Facts- Viruses > Flashcards

Important Key Facts- Viruses Flashcards

(65 cards)

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1
Q

How large are viruses usually ?
Exceptions

A

20-300 nm
Mimiviruses
Pandora virus = largest

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2
Q

What are the shapes of viruses ?

A

Helical - capsomers bonded in a spiral fashion
Polyhedral - capsid is roughly spherical
Binal ( complex ) - irregular shapes or complex structures

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3
Q

Give 2 examples of a helical virus

A

Tobacco mosaic virus
Rabies virus

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4
Q

An example of a polyhedral virus ?

A

Adenovirus

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5
Q

An example of a binal complex ?

A

Bacteriophages

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6
Q

What are the key functions of the Capsid ?

A

Protects the nucleic acid from enzymes
Attach to host cell
Penetrate host cell membrane

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7
Q

Is poliovirus naked/non-enveloped or enveloped ?

A

Naked

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8
Q

What is a virophage ?

A

Viruses that infect viruses

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9
Q

Are most bacteriophages enveloped ?

A

No

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10
Q

What type of viral genome do most bacteriophages have ?

A

DsDNA

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11
Q

6 stages of lytic bacteriophage cycle

A

Adsorption
Penetration
Replication
Maturation
Release
Reinfection

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12
Q

In the temperate phage cycle what does a prophage ( genome in host chromosome ) produce to block lytic genes ?

A

Repressor protein

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13
Q

What is the name of the cycle for the prophage replicating in the host chromosome ?

A

Lysogeny / lysogenic cycle

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14
Q

Are bacterial hosts that harbour a prophage immune to that bacteriophage’s infection ?

A

Yes

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15
Q

What stresses can cause the lytic cycle to resume in temperate phage life cycle ?

A

UV light or a toxin

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16
Q

What is the method of quantifying bacteriophages ?

A

Bacterial lawn

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17
Q

What are some uses of bacteriophages ?

A

Food safety
Disease therapy
Drivers of microbiota
Delivery vector
Biomarker of health / disease
Reporters of microbiome diversity

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18
Q

What group of DNA are Rhabdoviruses ?
What is an example and it shape ?

A

5 -ssRNA
Rabies
Bullet shape

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19
Q

Why does rabies virus use a +ssRNA intermediate in its replication cycle ?

A

-ssRNA cannot be directly transcribed by host ribosomes

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20
Q
A
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21
Q

How does rabies enter the brain ?

A

Enters peripheral nervous system through saliva of infected animal , migrates to the brain through CNS

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22
Q

How does rabies virus cause death ?

A

Encephalitis ( swelling of brain )

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23
Q

What are the 2 forms of rabies ?

A

Furious
Dumb

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24
Q

What is the difference between furious and dumb rabies ?

A

Furious - change to behaviour / voice , paralytic , death

Dumb - only 10-20 % cases , sleepiness , paralytic , death within 3 days

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25
What group of virus is Monkeypox ?
Group I virus - dsDNA
26
How many clades does monkeypox have ?
Two Congo basin or Central African clade West African clade
27
How does animal to human transmission occur in monkeypox ?
Bites and scratches from infected animals Preparation and handling of infected animal products (bushmeat) may also result in transmission
28
How does human-human transmission occur of monkeypox?
Via direct skin-skin contact with lesions on the skin Through indirect contact with contaminated fomites, such as bedding or clothing
29
What are the stages of skin presentation and progression of monkeypox rash ?
Macules Papules vesicles Pustules Scabs
30
How many licensed monkey pox vaccines are there ?
ACAM2000 - live vaccinia virus - single dose , lesion at inoculation site , by pricking skin surface Modified vaccinia Ankara (MVA) (Jynneos, Imvanex, Imvamune) - 2 subcutaneous vaccines 4 weeks apart , no lesion , safe in immunocompromised LC16m8 (modified vaccinia virus) - licensed in Japan - single dose, less replication ability , safer
31
What is a virioid ?
Infectious agent resembling a virus Smallest known pathogen
32
What type of genetic material does a virioid have ? Does it have a capsid ?
Small circular ssRNA (approx 250-500 nucleotides ) No capsid
33
What are virioids resistant to ?
Proteases and nucleases
34
Do viriods encode for any proteins ?
No
35
Do viriods infect animals and plants ?
No just plants
36
What are obelisks ?
A new class of virioid like elements that are first identified in human oral and stool metatranscriptomic data
37
What are the properties of obelisks ?
1. Apparently circular RNA 2. Predicted rod-like secondary structures 3. Open reading frames coding for a novel protein superfamily called oblins
38
What is a prion ?
Small proteinaceous infectious particles which resist inactivation and contain no genetic material
39
What are prion diseases often called ?
Spongiform encephalopathies
40
What are prion diseases caused by ? ( the disease mechanism )
PrPc ( glycoprotein ) is found in healthy animals mainly in neurons , playing a role in survival , adhesion , signaling etc Different folding form (PrPSC) exists , the two types interact Converting the healthy form to the other form ( PrPSC) changing the protein folding pattern , causing an accumulation , abnormal function
41
What is an example of a prion diseases often in sheep ?
Scrapie
42
Is Scrapie fatal ? What are its symptoms ?
Degenerative and fatal Ataxia - lack of controlled muscle movements , recumbency - in a lying position
43
Is there treatment for sheep with scrapie ?
No Selective breeding for resistant sheep, surveilalnce and depopulation - controlled measures
44
What is a prion disease in cattle ?
BSE ( bovine spongiform encephalopathy )
45
What is the main symptom of BSE ( mad cow disease ) ?
Erratic behaviour and movements
46
What was the method of the eradication programme ? How many presentations does BSE have ? Which can be passed to humans ?
4 million cows were killed Classical , H-type , L-type Classical can be transmitted
47
Which prion disease can humans get ?
CJD ( Creutzfeld-Jacob Disease ) from classical BSE
48
What are the main signs of CJD ?
Lose ability to think and to move properly and suffer from memory loss It is always fatal, usually within one year of onset of illness
49
What are the different types of CJD ?
**Sporadic CJD (sCJD)** - Sporadic CJD is the most common type. **Familial/inherited CJD** (fCJD) - Familial CJD is a very rare genetic condition where one of the genes a person inherits from their parent **Variant CJD (vCJD)** - is likely to be caused by consuming meat from a BSE Cow **Latrogenic CJD (iCJD)** - when the infection is accidentally spread from someone with CJD through medical or surgical treatment.
50
What size are viruses typically ?
0.01 - 0.2 µm
51
How were viruses named before a nomenclature was introduced ?
Host organism Geographic locations Scientists Type of disease Sites in the body Way of contracting the disease Cytopathology during infection Combination of all of these methods
52
What are the two main methods of taxonomy for viruses ?
International committee on the taxonomy of viruses (ICTV) Baltimore system of virus classification
53
The ICTV takes into account phenotypic characteristics and genotypic characteristics , T/F ?
True
54
What is group 1 of the Baltimore virus classification ? Give a few examples
Double stranded DNA viruses E.g herpesviruses , adenoviruses , poxviruses
55
What is group 2 of the Baltimore virus classification ? Example How is mRNA produced ?
Single stranded DNA ( ssDNA ) E.g parvoviruses SsDNA converted to dsDNA before it can be transcribed to mRNA
56
What is group 3 of Baltimore virus classification? Example
DsRNA Reoviruses e.g rotavirus
57
What is group IV of the Baltimore virus classification ? Example
+ssRNA Poliovirus , SARS-Cov-2 , dengue virus
58
What is group V in the Baltimore virus classification? An example ? How is mRNA produced ?
-ssRNA Rabies , Influenza , Ebola virus +ssRNA made from -ssRNA
59
What is group 6 of the Baltimore virus classification?
+ssRNA- RT with reverse transcriptase E.g HIV
60
61
What is group 7 of the Baltimore virus classification system ? Give an example
Gapped DNA genome Partial dsDNA is repaired to full dsDNA then to mRNA Hepatitis B virus
62
In a virus name , who creates for the disease , virus , clade and species ?
Disease - WHO Virus - Discoverer Clade - Scientists WHO consulted Species - ICTV
63
What are the possible ways that viruses infect cells ?
Transformation into a tumour cell Lysis Persistent infection Latent infection
64
What are the exceptions to viruses which do not need a receptor to attach ?
Fungal viruses - no extracellular phase , plant - enter by mechanical damage
65
What are the 3 possible mechanisms for how viruses enter cells ?
Injection of nucleic acids Fusion of envelope with host membrane Endocytosis

Biol121- Impact Of Microbes (5 decks)

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