Cytomegalovirus, EBV, Kaposi's Sarcoma- Associated Herpesvirus Flashcards Preview

Heme Week 2 > Cytomegalovirus, EBV, Kaposi's Sarcoma- Associated Herpesvirus > Flashcards

Flashcards in Cytomegalovirus, EBV, Kaposi's Sarcoma- Associated Herpesvirus Deck (53)
Loading flashcards...
1

T or F. CMV, EBV, and KSHV (HHV8) are all herpes viruses

T.

2

All share a tropism for what?

lymphocytes

3

Which of the three are oncogenic viruses?

EBV and KSHV

4

Describe the structure of herpesviruses.

-icosahedral capsid surround by a lipid envelope containing ~12 virally derived glycoproteins

tegumnet- has important proteins for replication

5

Describe the genome of herpesvirus.

large, linear, double-stranded DNA ca. 150-250 kilobase pairs

CMV is largest

6

How do herpesviruses replicate?

genome is replicated and viruses assembled in the nucleus

7

T or F. In general, herpesviruses produce self-limiting infections in which the primary infection is often asymptomatic.

However, life-threatening infections or cancers can occur, especially in immune compromised hosts (neonates, AIDS, etc.)

8

Is the replicative cycle of herpesviruses lytic or lysogenic?

lytic in a variety of cell types

9

Following virus attachment, how does viral penetration occur?

by virus glycoprotein- mediated fusion of envelope and plasma membrane (pH independent)

10

What does the released nucleocapsid do after entering the cell?

migrates to nuclear envelope via microtubules, uncoats, and DNA enters the nucleus. Virion components act to shut off host macromolecular synthesis

11

Then what happens?

Programmed expression of viral genes- cascade regulation

12

What is the order of proteins transcribed in these viruses?

- immediate early genes
- early genes
- late genes

13

What do immediate early (IE) genes encode?

virus-specific transcription factors

i. use host RNA polymerase II
ii. stimulate transcription at virus early promoters

14

What do early genes encode?

many nonstructural proteins, enzymes

15

Specifically, what kinds of proteins/enzymes do early genes encode?

-DNA replication machinery, including viral DNA polymerase

-thymidine kinase (tk) which phosphorylates a variety of nucleotides besides thymidine

16

What do late genes encode?

structural proteins (capsids, glycoproteins)

17

What is late gene transcription dependent on?

IE transcription factors and genome replication

18

Where does virus assembly occur?

nucleus- where nucleocapsids bud first into the perinuclear space

19

What happens after viral assembly?

virus particles migrate to the cell surface where they are released

20

What is latency?

situation in which entire genomes are maintained extrachromosomally in the host indefinitely, but no virus are produced

21

What are the stages of latency?

a. Establishment
b. Maintenance
c. Reactivation

22

When does reactivation generally occur?

when there is a lapse in immunity and results in the production of virus particles and recurrent infection

23

How many herpesviruses are there?

8- classified on basis of their genome arrangement and latency tropism

24

Describe alphaherpesviruses.

neurotropic for latency,

aggressive lytic growth

25

What are some types of alphaherpesviruses?

a.Herpes simplex virus (HSV)-1
b.HSV-2
c.Varicella-zoster virus (VZV)

26

Describe betaherpesviruses.

lymphotropic for latency,

more insidious

27

What are some types of betaherpesviruses?

a.Cytomegalovirus (CMV)
b.Human herpesvirus-6 (HHV-6)
c.HHV-7

28

Describe gammaherpesviruses.

lymphotropic for latency,

more insidious

29

What are some types of gammaherpesviruses?

EBV
HHV-8 (Kaposi's sarcoma)

30

T or F. CMV is highly contagious

F. Still, in low socioeconomic classes, infection is at 1 to 2 years of age and up to 80% of adult population is CMV positive

In higher socioeconomic classes, CMV is typically acquired after 16 years of age and only about 50% of the adult population is CMV positive