Exam3Lec2Retroviruses/OncogenicViruses Flashcards
What genus of the retroviridae family affects human? What are its features and list its examples
list the two related to this lecture
- Deltaretrovirus, complex onco, human T cell leukemia virus
- Lentivirus, complex, humman immunodeficiency virus
What genus of the retroviridae family affects animals? What are its features and list its examples
alpha,betam and gamma retrovirus. features for all three are simple and oncogenic
examples: alpha-ALV (avian leukemia virus)
beta- MMTV (mouse mammry tumor virus)
gamma -MLV (murine leukemia virus)
Explain the retrovirus virion
It has a genome with a capsid in lipid bilayer
TM: transmembrane holds the globualar part
When it comes into the cell, it has to break in and it does rev. transcriptase.
What is the nuclear phase of replication of retroviruses?
Integrate into host genome (provirus)
All contain reverse transcriptase
turns RNA genome into cDNA provirus, this integraates into host genome
What are the two classes of retroviruses?
- Simple retroviruses: encode Gag, Pol, and Env. Requires cell division for integration
- Complex retroviruses: encode Gag, Pol, Env + several small regulatory proteins. (more in their genome) DO NOT require cell division for integration. (Ex: HTLV-1 & HIV)
nucelor import of retrovirus proviral DNA
Explain the retrovirus life cycle (replication)
- Receptor mediated membrane fusion or penetration then partial uncoating
- Rev transcriptase and RNAse-H
- nuclear translocation and Integration of cDNA into genome of the host (cDNA moves into nucleus)
host cell machinery takes over - Transcription: RNA is exposed and spliced to make diff proteins
- Translation of viral protein: 2 copies of RNA. One does capsid assembly other goes through golgi They both then move to membrane for budding
- Protease mediated virion maturation after budding (release by budding)
after they uncoat, they use rev transcriptase to make dna copy of genome, goes into nucleus and integrates into provirus genome
What are 4 unique features of retroviral replication?
- Diplpid +RNA genome
- Genome is not directly translated
- Genome is reverse transcribed into cDNA provirus
- Integration of provirus into infected cell chrmosome
1st rev. transcription to make cDNA proteins and then it integrates into cell DNA. Then provirus is transcribed
Explain the structure of Proviral DNA?
- LTR: long terminal repeat (provides promoter activity)
- GAG: structural proteins of virion
- POL: Enzymatic activities
- ENV: virion envelope glycoprotiens
What is LTR?
Long terminal repeat. It is the “gps” for DNA provirus to make sure it integrates into the right area in the host genome
it does this by copying both sides of RNA genome and thats how cDNA knows where to go.
What is GAG?
structural proteins of the virion
MA: matrix
CA: capsid
NC: nucleocapsid
What is POL?
Enzymatic activities
RT: reverse transcriptase
RN: RNaseH
PR: Protease
IN: Integrase
What is ENV?
virion envelope glycoproteins
SU: surface
TM: transmembrane
What are the two types of oncogenic retroviruses?
Transducing and Non-transducing
What are transducing oncogenic retrovirsues?
HIGHLY carcinogenic
Cause cancer because their genomes contain altered cellular genes called v-oncogenes which are transduced.
cause malignancies in 100% of infected animals in a matter of days
What are non-transducing oncogenic retroviruses?
LESS carcinogenic
DO NOT encode v-oncogenes
Activate transcription of proto-oncogenes by integration of the provirus
do not 100% cause cancer
What do Viral Oncogenes alter?
- Growth factors
- Growth factor receptors
- Intracellular tyrosine kinases
- Serine/Threonine kinases
- Signal transduction proteins
- Transcription factors
What is Human T-Lymphotropic Leukemia Virus?
retro family
(+)ss, enveloped, ico, 2 copies per virion (diploid)
replications in nucleus (reverse transcriptase integration)
Transmission: Sexual (bloodborne)
Tropism: T cells
these are in humans
What clinical diseases we see with HTLV-1
Clinical disease: Adult T cell Leukemia (ATL) and HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP)