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