3.8 (1) Retroviruses Flashcards
retroviruses:
- genome
- enveloped/nonenveloped
2 copies of ssRNA
enveloped
what type of cells do retroviruses infect
CD4+ lymphocytes
what is unique about replication machinery of retroviruses
they have reverse transcriptase (RNA -> DNA)
what is the role of reverse transcriptase
after infection, RT converts the RNA genome into dsDNA, which then integrates into the host genome
how are retrovirus genes transcribed and translated
from the genome integrated viral DNA
what does the following encode:
- gag
- pro
- env
- pol
gag: structural proteins
pro: proteases
env: envelope
pol: polymerase
what are the 3 functions of the polymerase of retroviruses
1) RNA-dependent DNA polymerase (reverse transcriptase)
2) DNA dependent DNA polymerase
3) RNAse
what are the 5 genera of retroviruses
alpharetrovirus, betaretrovirus, deltaretrovirus, gammaretrovirus, lentivirus
name an important alpharetrovirus
avian leukosis virus (ALV)
name an important deltaretrovirus
bovine leukemia virus (BLV)
name an important gammaretrovirus
feline leukemia virus (FeLV)
name an important lentivirus
feline immunodeficiency virus (FIV)
T/F lymphoma and lymphosarcoma are synonymous
T
leukosis is the basis of
leukemia
________ is the basis of leukemia
leukosis
what is leukosis
neoplastic proliferation of leukocyte-forming tissue
avian alpharetroviruses can be classified as (3)
exogenous replication competent, exogenous replication incompetent, endogenous avian leukosis viruses
describe exogenous replication competent viruses
- transmitted horizontally or congenitally
- usually slow tumor development because they do not have their own oncogenes
- tumors arise from insertion mutations
describe exogenous replication incompetent viruses
- have an oncogene but lose viral proteins
- require a helper virus for replication
- rarely transmitted
- rapidly transform because of the oncogene
describe endogenous avian leukosis viruses
- proviruses in somatic and germline genome
- transmitted genetically only
where is avian leukosis virus commonly seen and where is it rarely seen (what type of flocks)
commonly seen in backyard chickens, low occurence in commercial flocks
does avian leukosis virus have a fast or slow rate of tumor development
slow