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11 Cards in this Set

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Where do viral oncogenes come from?
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.
What is a defective acute transforming virus?
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.
What is HTLV-1.
It is human T cell leukemia virus. It has been linked to a paralytic diseasethat occurs in the tropics called tropical spastic paraparesis.`
What is HTLV-11?
A second human retrovirus was isolated from T cells of patients with a T cell variant of hairy cell leukemia.
Immunodeficiency occurs with other animal retroviruses, such as feline leukemia virus. TRUE/FALSE
TRUE. The known human retroviruses HTLV-1 and 11 were both T cell tropic.
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
TRUE.
A virus that causes an AIDS like disease in primates, Simian immunodeficiency virus(SIV) shares a close sequence homology with HIV-1.
What does the HIV virus look like?
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.
What is icosahedral symmetrythe p24 protein?
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.
What is the HIV genome?
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.
What are LTRs?
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.
What is the gag antigen?
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.