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):
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

31

Where is CMV found in the body?

- saliva
-urine
-breast milk
-semen
-cervical secretions
-blood
- transplant organs

32

Who is at risk for CMV?

- neonates
- day care workers
- pregnant workers
- immunocompromised ppl
- gay men

33

How is CMV spread?

contact with secretions- not by aerosol

34

Where does CMV replicate?

epithelial cells, followed by spread to lymphoid tissue

35

CMV latently infects what cell types?

B-cells, T-cells, monocytes, and lymphocytes where it causes large, puffed up cells

36

What are the symptoms of CMV infection in utero?

- mostly asymptomatic
- retardation and deafness possible

37

What are the symptoms of CMV infection in adulthood?

-most asymptomatic
-mononucleosis accompanied by fever can occur

38

CMV is especially common in which patient population?

transplant recipients

Can result from infection by CMV+ donor or by reactivation of CMV+ recipient

39

CMV in transplant patients is often associated with what?

pneumonitis

40

How can CMV infection in transplant patients be prevented?

- prophylactic treatment with CMV Ig and ganciclovir

41

AIDS patients with CMV are prone to what?

retinitis
colitis
pneumonitis

42

How is CMV diagnosed?

-ELISA or PCR detection

-Shell vial assay in which indirect immunofluorescence is used to detect an immediate early protein after 24 h of cell culture infection

43

What are the treatment options for CMV?

-Ganciclovir
-Foscarnet
-Cidofovir

44

What is Ganciclovir?

a guanosine analog similar to acyclovir, the prototype which is used in HSV, VZV, and EBV infections

45

What does ganciclovir require for activity?

phosphorylation by viral kinase

Triphosphate form preferentially inhibits CMV polymerase but is more toxic to host than ACV

46

Side effects of ganciclovir?

neutropenia
GI bleeding

47

What is ganciclovir approved for?

- treatment of transplant patients
- treatment for CMV retinitis - treatment in AIDS patients

48

What is Foscarnet approved to treat?

- CMV retinitis in AIDS patients

same for Cidofovir

49

How does Foscarnet work?

Pyrophosphate analog that inhibits DNA polymerase, but does not require phosphorylation for activity

50

How does Cidofovir work?

it is a deoxycytidine analog that is a competitive inhibitor of CMV (and HSV) DNA polymerase, but not does require viral kinase action for activity

51

What is CMV possible linked to?

glioblastoma multiforme

52

How does Acyclovir work?

guanosine analogue that enters the body and must have 3 phosphates put on it to work. The first is added by a virally derived thymidine kinase (thus, it is specific to only infected cells), and the last two by host kinases. Once incorporated, it disrupts DNA production

53

T or F. Oncogenesis is the result of latency, not acute infection

T.