Virus Structure and Classification and Mechanisms of Replication

Question 1

Largest virus:

Answer 1

Poxvirus.

Question 2

Smallest virus:

Answer 2

Parvovirus.

Question 3

Three capsid shapes:

Answer 3

1. Icosahedral.
2. Complex.
3. Helical.

Question 4

Tropism:

Answer 4

Host cell specificity.

Question 5

Cytopathic effect:

Answer 5

CPE: Type of morphological changes of infected cells.

Question 6

Neutral red stains:

Answer 6

Viable cells.

Question 7

Multiplicity of infection:

Answer 7

MOI: Number of infectious virus particles added per cell to initiate infection.

Question 8

Plaque forming units:

Answer 8

Measure of infectious virus:

• 1 PFU = 1 infectious virus
• Plaque = localized areas of dead cells in a cell monolayer.

Question 9

Foci:

Answer 9

Proliferation of transformed cells in localized areas of a cell monolayer

Question 10

Hemagglutination:

Answer 10

Virus-erythrocyte lattice formation:

- Hemagglutinin on virus surface binds to receptors on the surface of specific erythrocytes.

Question 11

Hemadsorption:

Answer 11

RBCs attach to surface of infected cells via viral proteins (hemagglutinins).

Question 12

Viropexis:

Answer 12

Phagocytic engulfment or endocytosis of virus by cell after attachment to receptor.

Question 13

Fusion:

Answer 13

Enveloped viruses: fuse with viral envelope, dependent upon viral proteins which mediate fusion.

Question 14

Virus where nucleic acid synthesis occurs in both the nucleus and cytoplasm:

Answer 14

Influenza virus.

Question 15

Virus maturation:

Answer 15

Assembly of viral components to form intact virions, occurs at specific sites within the cell.

Question 16

Inclusion bodies:

Answer 16

Localized areas within infected cells containing viral components or virus particles.