Virology

Question 1

Components of a naked virus with an icosahedral capsid?

Answer 1

Capsid + nucleic acid

Question 2

Components of an enveloped virus with an icosahedral capsid?

Answer 2

Capsid + nucleic acid + lipid bilayer + surface protein

Question 3

Components of an enveloped virus with a helical capsid?

Answer 3

Helical nucleocapsid with integrated RNA + lipid bilayer + surface protein

Question 4

Exchange of viral genes between 2 chromosomes by crossing over within regions of significant base sequence homology

Answer 4

Viral recombination

Question 5

Exchange of genetic material between segmented viral genomes

Answer 5

Viral reassortment

Question 6

What type of viral genetic process can cause antigenic shift?

Answer 6

Viral reassortment (seen in the novel H1N1 influenza A pandemic)

Question 7

What is viral complementation?

Answer 7

When 1 of 2 viruses that infect the cell has a mutation that results in a nonfunctional protein, the nonmutated virus “complements” the mutated one by making a functional protein that serves both viruses

Question 8

Give an example of viral complementation.

Answer 8

Hepatitis D - requires the presence of replicating hepatitis B virus to supply HBsAg, the envelope protein for HDV

Question 9

What is viral phenotypic mixing?

Answer 9

When a cell is simultaneously infected (coinfected) with 2 viruses, the genome of virus A can be partially or completely coated with the surface proteins of virus B - this forms a pseudovirion. This type B protein coat determines the tropism (infectivity) of the hybrid virus. However, the progeny from this infection have a type A coat that is encoded by its type A genetic material. There is NO change in the underlying genome.

Question 10

List the killed viral vaccines.

Answer 10

Rabies
Influenza (injected)
Polio (Salk)
HAV

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“SalK = Killed”

Question 11

List the live attenuated viral vaccines.

Answer 11

MMR
Yellow fever
Rotavirus
Influenza (intranasal)
Chickenpox (VZV)
Smallpox
Sabin polio virus

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Question 12

List the subunit viral vaccines.

Answer 12

HBV (HBsAg)

HPV (types 6, 11, 16, 18)

Question 13

List the negative-stranded viruses.

Answer 13

Arenaviruses
Bunyaviruses
Paramyxoviruses
Orthomyxoviruses
Filoviruses
Rhabdoviruses

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Question 14

What is a negative-strand virus?

Answer 14

Virus that must transcribe the negative strand to a positive strand using its own RNA-dependent RNA polymerase

Question 15

List the segmented viruses.

Answer 15

Bunyaviruses
Orthomyxoviruses (influenza viruses)
Arenaviruses
Reoviruses

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