Lecture 9 2/12/24 Flashcards

1
Q

What are the general characteristics of neg. strand RNA viruses?

A

-genome is complementary to mRNA
-cannot be directly translated by host cells
-RdRp required to transcribe neg-sense RNA into pos-sense RNA before protein synthesis

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2
Q

What are the characteristics of vesicular stomatitis virus?

A

-neg. ssRNA genome
-bullet-shaped
-enveloped
-helical symmetry
-Rhabdoviridae fam.
-easily manipulated and used to study other viruses

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3
Q

What happens when the VSV genome is transcribed into + sense RNA and used to produce mRNA?

A

the mRNA is made up of a bunch of small fragments that each encode a viral protein

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4
Q

What are the characteristics of influenza virus?

A

-Orthomyxoviridae family
-enveloped
-eight segments of (-)ssRNA
-two major surface proteins, HA and NA

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5
Q

What are the four types of influenza viruses?

A

-A: humans, birds, pigs, horses, mammals
-B: humans, aquatic mammals
-C: humans, pigs
-D: cattle, pigs

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6
Q

What determines the species that each influenza virus will infect?

A

the type of sialic acid that the virus binds to

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7
Q

Which type of sialic acid does influenza bind to in humans?

A

alpha-2,6

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8
Q

Which type of sialic acid does influenza bind to in avian species?

A

alpha-2,3

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9
Q

How does influenza begin its replication process?

A

cap snatching

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10
Q

What is antigenic shift?

A

-when two influenza viruses infect same host cell and exchange genetic material
-creates a new strain with different genetic makeup

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11
Q

What is antigenic drift?

A

-occurs when mutations arise in influenza genome over time
-small changes in viral genetic makeup

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12
Q

Which other neg. ssRNA viruses are of importance?

A

-paramyxoviruses
-bunyaviruses

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13
Q

What are the characteristics of reoviruses?

A

-dsRNA genome
-non-enveloped
-capsid structures with two layers

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14
Q

Which animal viruses are reoviruses?

A

-avian orthoreovirus
-bluetongue virus
-African horse sickness virus

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15
Q

Why can reoviruses not immediately produce mRNA?

A

the pos. sense strand is not accessible to ribosomes due to the double stranded structure

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16
Q

What are the three types of reovirus particles?

A

-virion: infectious virus form
-infectious sub-viral particle: missing first capsid coat
-core: missing both capsid coats and allows for mRNA exit

17
Q

How do the dsRNA segments of reoviruses attach to RdRp?

A

via a 5’ cap

18
Q

What leads to diversity among RNA viruses?

A

-misincorporation of nucleotides
-lack of proofreading activity in RdRp

19
Q

Which type of virus DOES have proofreading ability due to the presence of an exonuclease?

A

Nidovirales