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22 Cards in this Set

  • Front
  • Back
The RNA genome of Retroviruses is converted to a linear DNA molecule via
Reverse transcription.
Viral DNA integrates into host chromosomes.
Proviral DNA directs the synthesis of viral mRNAs and proteins.
Viral particles bud off cell membrane.
What are three genes associated with simple retroviruses?
Antigen (gag)
polymerase (pol)
envelope (env)
What relevant additional genes do complex retroviruses have?
Additional regulatory genes which control viral gene expression
What are some additional regulatory genes in HTLV-1 and HIV
HTLV-1 tax, rex
HIV tat, rev, nef, vpr, vpu, vif
The process by which retroviral insertion occurs randomly in the host chromosome and disrupts host genes is known as:
Insertional mutagenesis
Naturally occurring cancer viruses are known as
Non-acute Oncogenic Retroviruses
When viral long terminal repeats (LTR) are integrated near or within the host proto-oncogene locus thereby augmenting its transcription, it is known as:
Cis-activation
What are endogenous retroviruses?
Retroviral proviruses or proviral remnants that are incorporated into germ line cells and transmitted vertically, comprising 1-5% of the mammalian cell genome
Why is HIV being explored as a vector (lentivirus vector) for gene transfer into cells such as neurons
It is uniquely capable of infecting non-dividing cells
What are three diseases cause by HTLV-I?
1. Adult T-cell leukemia/lymphoma
2. A neurodegenerative disease called tropical spastic paraparesis or HTLV-associated myelopathy (TSP/HAM)
3. Other inflammatory diseases such as infective dermatitis, uveitis
Describe Adult T-cell Leukemia
A rare malignancy of CD4+ T-cells, long clinical latency, invariably fatal.
Describe Tropical Spastic Parapesis/HTLV-1 Associated Myelopathy
Activation of CD4+ T-cell, inflammation of the spinal cord, paralysis of the lower extremities
How is HTLV-I transmitted?
Via breast milk, by sexual intercourse (rare), and by transfusion of cell-containing blood components
What are the clinical characteristics of TSP/HAM?
TSP/HAM is characterized by uncoordinated motor control, and the pyrimidal tracts of the spinal cord which carry motor neurons show degenerative demyelination
Caused by HTLV-1
What are the three types of retroviruses
Oncoviruses
Lentiviruses
Spumaviruses
What is the structure of Retroviruses
Medium sized, enveloped viruses
Gag proteins are involved in what
Retrovirus assembly and packaging of the RNA genome
What do the env gene products do
They mediate the attachment of retrovirus to the cell receptor and fusion of the viral envelope with the host cell membrane
Why can the immune system never eliminate Retroviruses
Permanent integration into host DNA
What are retroviral LTRs
Long terminal repeats, identical regions on each end of the proviral DNA. Retroviral LTRs are among the most potent promoters for gene expression in mammalian cells
What genes does HTLV-1 tax gene activate
Many cellular genes, including cytokine genes
What disease is HTLV-II associated with
T-cell hairy cell leukemia