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BSCI437: General Virology > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

Components of a virus

A

Genome (DNA or RNA) & Protein

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2
Q

Functions of viral genomes

A
  1. Specify proteins
  2. Serve as a template for synthesis of progeny genomes
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2
Q

3 kinds of genome configurations & size

A

-Linear, entire genome on 1 strand
-Linear, segmented genome
-Circular genome

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3
Q

Types of genome modification

Four total

A

-Cap
-Poly A tail
-Viral proteins
-Cellular proteins

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4
Q

Role of secondary & tertiary structures in viral genomes

Four total

A

-Replication
-mRNA Synthesis: Recognition points for binding of viral or host proteins
-Packaging of the genome: Serves as signal to allow the genome but not other DNA/RNA to be put into viral particle
-Triggering the host innate antiviral response

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5
Q

Functions of genome modifications

4 main functions

A

-Aid in translation
-Stability of genome
-Packaging of genome
-Protect from host detection

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6
Q

How viruses deal with limited size

7

A

-Hijack host proteins for some or all replication functions
-More than one protein/gene
-Overlapping genes
-Genes on both strands of DNA
-Multiple splicing of same transcript to make numerous proteins with only one promoter
-Frameshift mechanisms allow downstream out of frame genes to be made at appropriate proportions
-Polyprotein production from one mRNA and subsequent proteolytic cleavage

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7
Q

Limits of genome size

4

A

-Replication rate: Especially in bacteria where virus must keep up with host since a large genome takes too long to replicate
-Size of virus particle: Larger the genome the larger the particle host must be
-Stability of genome
-Mutation rate of polymerase: Too many=loss of genome integrity, Not enough=Failure to adapt

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8
Q

Morphological unit

A

Surface structure seen by electron microscope

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8
Q

Capsid

A

Protein shell of a virus

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9
Q

Between ______% of viral particle mass is from protein

A

50-90%

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9
Q

Capsomere

A

A discrete component of a capsid, constructed from several identical protein molecules

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10
Q

Nucleocapsid

A

Viral nucleic acid enclosed in a protein capsid

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11
Q

Functions of virion proteins

3

A

-Protection of the genome
-Delivery of the genome
-Other interactions with the host

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11
Q

Envelope

A

Lipid bilayer containing viral glycoprotein

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12
Q

Assembly/Disassembly Paradox

A

Virus must be stable and protective enough to enter a host but fragile enough to disassemble within the host

13
Q

How lipid bilayer is acquired from most cells

A

-Most acquired from hosts plasma membrane
-Others bud from internal membranes such as endoplasmic reticulum

13
Q

Capsid function

A

-Protect genome from the atmosphere
-Delivery of genome in infectious form

13
Q

Viral enzymes for which there are no host counterparts

In RNA, Vaccinia, and HIV

A

-RNA viruses: RNA-dependent RNA polymerase
-Vaccinia: DNA Dependent RNA Polymerase
HIV: Reverse transcriptase, Integrase, VPR (Helps evade host innate antiviral response

14
Q

3 properties of helical viruses

A
  1. Positive charge interacts with nucleic acid
  2. Hydrophobic with proteins on either side
  3. Negative charge with polar environments
14
Q

Cellular components of retroviruses

2

A
  1. Host cell tRNAs that function as primers for reverse transcription
  2. HIV: Cyclophilin A plays a role in infectivity
14
Q

Hepatitis C virus

A

Associated with host lipoproteins

14
Q

Hepatitis A virus

Physical Characteristic

A

Does not have an envelope when found in the environment, but acquires one from the cells that it grows in within the liver

15
Q

Why study virion structure

3

A

-Attachment of host receptors
-Process of viral entry
-Process of viral assembly & disassembly

16
Q

Function of virion proteins in protection of the genome

3

A

-Specific recognition and packaging of the viral genome
-Assembly of a stable, protective protein shell
-Interaction with host cell membranes to form the envelope

17
Q

Function of virion proteins in delivery of genome

5 total: Emphasis on Delivery

A

-Specific binding to cellular receptors
-Induction of fusion of the viral envelope with cellular membranes
-Transmission of fusion of the viral envelope with cellular membranes
-Transmission of signals required for uncoating
-Interaction with cellular components to direct translocation of the viral genome to the appropriate sitw

18
Q

Function of the virion proteins in other interactions with the host

3

A

-Ensures efficient infectious cycle
-Transport of viral components to assembly sites
-Host immune system interaction

BSCI437: General Virology (14 decks)

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