Virus Lecture 18

Question 1

After entry the infectivity of the virus particles disappear, this is called?

Answer 1

Eclipse

Question 2

What causes the eclipse?

Answer 2

The uncoating of the virus particles.

Question 3

What happens during the latent period?

Answer 3

Replication of viral nucleic acid and protein occurs and there is no sign of significant infection.

Question 4

When a virus nucleic acid and protein are assembled to mature virus particles is called?

Answer 4

Maturation period

Question 5

Where are the attachment site for animal viruses?

Answer 5

All over the surface

Question 6

What are the virus receptors of the cell made of?

Answer 6

Protein and glycoprotein

Question 7

T:F Receptor sites are host specific and varies between virus groups.

Answer 7

True

Also varies between person to person

Question 8

Virus entry is receptor mediated through?

Answer 8

Endocytosis

Question 9

Fusion is?

Answer 9

The means by which enveloped viruses enter cell.

Question 10

The removal of capsid protein and release of nucleic acid is known as?

Answer 10

Uncoating

Question 11

When does uncoating happen?

Answer 11

During the eclipse period

Question 12

What are needed for uncoating?

Answer 12

Lysosomal enzymes and host cell enzymes

Question 13

What large virus has its own uncoating enzymes?

Answer 13

Pox virus

Question 14

Active viremia is?

Answer 14

Viremia following virus replication in the host

Question 15

Viremia is?

Answer 15

The presence of virus in the blood

Question 16

The direct inoculation of virus in host, such as contaminated syringe or bite of arthropods is known as?

Answer 16

Passive Viremia

Question 17

T:F Replication happens in passive viremia.

Answer 17

False

No replication happens at site/port of entry

Question 18

What are the effects of virus infections?

Answer 18

Transformation of normal cells to tumor cells
Lytic infection
Persistent infection
Latent infection

Question 19

Mechanisms of viral injury and disease:

Answer 19

Inhibition of host-cell nucleic acid synthesis
Inhibition of host-cell RNA transcription
Inhibition of host-cell protein synthesis
Cytopathic effect of “toxic” viral proteins interference with cellular membrane
Neoplastic transformation
Drive host cell to apoptosis (cell suicide)
Non-cytocidal changes (persistent infection)

Question 20

What is a provirus?

Answer 20

A virus genome that is integrated to the DNA of a host cell.

Question 21

What is a prophage?

Answer 21

In the case of bacteriophages, virus genome that is integrated into the DNA of a host cell (bacteria).

Question 22

What are retroviruses?

Answer 22

A family of enveloped viruses that are single stranded RNA and use reverse transcription to replicate.

Question 23

What is the difference between primary cell lines and diploid cell lines?

Answer 23

Primary cell lines are derived from tissues and die after a few generations
Diploid cell lines are developed from human embryos and can grow for 100 generations

Question 24

What are continuous cell lines?

Answer 24

Are transformed (cancerous) immortal cell lines

Question 25

PCR testing for RNA viruses what do you need in addition to the regular PCR components?

Answer 25

Reverse transcriptase