RETROVIRUS

Question 1

GENERAL CHARACTERISTICS
RETROVIRUSES
KEY ENZYMES
RT
P
I

Answer 1

Reverse transcriptase
Protease
Integrase

Question 2

GENERAL CHARACTERISTICS
Essential Genes in all replication competent retroviruses

5-gag-pro-pol-env-3

Answer 2

Gag- core proteins
Pro - protease
pol- polymerase
env - envelope glycoproteins

Question 3

RETROVIRIDAE FAMILY IS DIVIDED INTO 7 GENERA
but two are very important
1._________- Human T Lymphotropic viruses and bovine leukemia virus
2._______- agents able to cause chronic infections with slowly progressive neurologic impairment including HIV

Answer 3

1. Deltraretrovirus
2. Lentivirus

Question 4

RETROVIRUSES CLASSIFICATION
TRANSMISSION CATEGORIES
1.__________
Spreads horizontally like sex or blood; behave as typical infectious agents
2.__________
vertically transmitted through the germ line
integrated into the genetic constitution of all cells in a species often repressed

Answer 4

1. EXOGENOUS
2. ENDOGENOUS

Question 5

RETROVIRUSES
1._______________
carry viral oncogenes from cellular genes
induce tumors in vivo
induce morphologic changes

2.___________
do not carry an onc gene
causes tumors usually leukemias and lymphomas
insertional mutagenesis: viral promoter activates nearby protooncogene

Answer 5

1. acute transforming virus
2. slow transforming

Question 6

RETROVIRUS
SLOW TRANSFORMING VIRUSES

Insertional mutagenesis: ___________ activates nearby proto-oncogene and converts protooncogene to oncogene

Answer 6

viral promoter

Question 7

HUMAN T-LYMPHOTROPIC VIRUSES

_______ is the causative agent of Adult T-cell leukemia-lymphoma ATL and HAM/TSP (prgressive neurological weakness)

Answer 7

HTLV-1

Question 8

LENTIVIRUSES

MORPHOLOGY: bar shaped nuck
single stranded RNA (+) sense with envelope

1.____________: envelope glycoproteins and crucial for binding and fusion
2._______: cone shaped capsid protein used as diagnostic marker in 4th generation assays

Answer 8

1.gp120/gp41
2. p24

Question 9

HIV
exhibits tropism for ______ and myeloid cells

Answer 9

CD24 T cells

Question 10

HIV ACCESSORY GENES
1.__________: early phase replication protein; functions in transactivation

2.__________: increases viral infectivity activates resting T cells and downregulates expression of CD4 and MHC class 1

3.__________: required for expression of viral structural proteins; exports unspliced viral transcripts from the nucleus

4.__________: increases transport of viral preintegration complex into the nucleus

Answer 10

1. tat protein
2. nef protein (negative early factor)
3. rev protein
4. vpr protein

Question 11

ACESSORY GENES
1._________: one of intracellular antivaral inhibitory proteins referred to as restriction factors

Answer 11

APOBEC3

Question 12

REPLICATION CYCLE RETROVIRUS
1-2 ADSORPTION AND PENETRATION (attachment and fusin)
- mediated by viral envelope
- glycoproteins interact with specific cell surface receptors 1.___________
- requires coreceptor 2.___________ (early infection) or 3.__________ (late stage)

Answer 12

1, gp120/gp41
2. CCR5
3. CCR4

Question 13

FORMATION OF HIV LATENCY
______:
Persists indefinitely in a stable latent reservoir of resting memory CD4-T cells making a cure nearly impossible with current therapy

Answer 13

Reservoirs

Question 14

CLINICAL STAGES OF UNTREATED HIV
1. ________
There is a 4-11 day period between mucosal infection and initial viremia
2._________-
50-75% of patients significant drop of numbers of circulating CD4 cells

Answer 14

1. viral infection
2. acute mononucleosis like syndrome