Viral genetics Flashcards

1
Q

ssDNA viruses

A

Often small
Can be +, -, or ambisense

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2
Q

dsDNA viruses

A

Have the largest and most complex genomes
Most stable genome
DNA dependant DNA polymerase have high fidelity

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3
Q

+ssRNA viruses

A

Size limited due to RNA fragility
Higher mutation rate because RNA dependent RNA polymerase are more error prone (except coronaviruses)
Majority of plant viruses

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4
Q

The majority of plant viruses are which type?

A

+ssRNA

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5
Q

-ssRNA viruses

A

More genome diversity than +ssRNA
Gene expression and genome replication is harder
Often segmented to increase stability
Must bring its own RNA polymerase

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6
Q

Which virus is segmented?

A

-ssRNA

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7
Q

Which viruses must bring its own polymerase?

A

-ssRNA

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8
Q

Reverse transcription

A

2 +ssRNA to 1 dsDNA
Very error prone = rapid genetic variation
2 +ssRNA copies promotes recombination
dsDNA integrates into host genome for lifelong infection

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9
Q

Why don’t we need to worry about bacteriophages?

A

Genome not recognizable and decidable by our cells

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10
Q

Viral genome compression

A

Selective pressure to maximize genetic capacity and minimize genome size

Dense genome increases replication rate compared to host

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11
Q

Gel electrophoresis

A

Nucleic acids are negative

Useful for analyzing intact genomes, segmented genomes, and sequencing

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12
Q

PCR

A

Allows detection of minuscule amounts of viral nucleic acids

Use RT-PCR for RNA viruses

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13
Q

Transfection

A

Infection of cells by nucleic acids alone (use plasmids of each gene)

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14
Q

Transduction

A

Transfer of genome from packaging cell to the target cell

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15
Q

Strain

A

Same viruses but different isolates (flu from two countries)

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16
Q

Type

A

Serotype of the same viruses (Dengue 1-4 produce different antibody responses)

17
Q

Variant

A

Mutant with different phenotype from WT (Covid variants)

18
Q

Which viruses have a higher rate of mutation?

A

RNA because their polymerase can’t proofread (except coronaviruses)

19
Q

Quasi species

A

Mixture of viral genomes in a population

20
Q

Defective Interfering (DI) particles

A

Non infectious
Takes up machinery
Can trigger immune response

21
Q

Consequences of superinfection

A

Complementation - increase fitness of one or both parents

Recombination - occurs in all DNA viruses and only RNA viruses with a DNA intermediate

Reassortment - segmented genomes get mixed

22
Q

Virome

A

All viruses in a given environment