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11 Cards in this Set
- Front
- Back
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Where do viral oncogenes come from?
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Somehow, during normal viral infection and integration, a mistake in splicing occurs and a virus captures a protooncogene. This proto-oncogene is activated in the virus so the virus now carries an oncogene.
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What is a defective acute transforming virus?
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The oncogene gene sequence is so long that most acute transforming viruses have lost their own RNA critical for viral replication. These viruses require a coinfecting virus to cause cancer.
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What is HTLV-1.
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It is human T cell leukemia virus. It has been linked to a paralytic diseasethat occurs in the tropics called tropical spastic paraparesis.`
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What is HTLV-11?
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A second human retrovirus was isolated from T cells of patients with a T cell variant of hairy cell leukemia.
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Immunodeficiency occurs with other animal retroviruses, such as feline leukemia virus. TRUE/FALSE
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TRUE. The known human retroviruses HTLV-1 and 11 were both T cell tropic.
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A second retrovirus called HIV-2 causes a disease similar to AIDS in western Africa. It is a distantly related virus with 40% sequence homology with HIV-1. TRUE/FALSE
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TRUE.
A virus that causes an AIDS like disease in primates, Simian immunodeficiency virus(SIV) shares a close sequence homology with HIV-1. |
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What does the HIV virus look like?
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It appears as a sperical enveloped virion with a central cylindrical nucleocapsid.
At the virion core lie 2 identical SS RNA pieces(dimer). Associated with these are nucleocapsid(NC) proteins bound to the RNA and the three essential retroviral enzymes, protease/reverse transcriptase/integrase. |
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What is icosahedral symmetrythe p24 protein?
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Surrounding the RNA dimer lies the capsid shell which has icosahedral symmetry. the proteins that constitute this shell are called capsid proteins(CA). The major capsid protein is p24; this can be measured in the serum to detect early HIV infection.
The surface glycoproteins are referred to as gp followed by a number;gp120 and gp41. |
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What is the HIV genome?
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All retroviruses possess in their RNA genome, two ending long terminal repeat(LTR) sequences, as well as the gag gene, pol gene, and env gene.
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What are LTRs?
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These flank the whole viral genome and serve 2 imporatnt functions.
a. Stick ends; these sequences recognized by integrase are involved in insertion into the host DNA. These are like transposons. b. Promotor/enhancer; once incorporated into host DNA, proteins bind to the LTRs that can modify viral DNA transcription. |
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What is the gag antigen?
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Group antigen. These sequences code for proteins inside the envelope; nucleocapsid(NC), capsid(CA) called p24 and matrix(MA) proteins. Gag codes for the virions major structural proteins that are antigenic.
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