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17 Cards in this Set

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What is the pol gene?
The pol gene encodes the vital protease, integrase, and reverse transcriptase enzymes.
protease is a vital HIV enzyme that cleaves gag and pol proteins from their larger precursor molecules(post translational modification)
new drugs have been developed that blocked the action of the HIV enzyme, protease. TRUE/FALSE
TRUE. Therapy with these inhibitors reduces HIV levels and increases CD4-T-lymphocyte cell counts.
What does "env" gene code for?
It codes for the ENVelope proteins that once glycosylated, form the glycoprotein spikes gp120 and gp41 the stalk. Together, they are called gp160 and bind to CD4 receptors on T cells.
What does the "tat" gene encode?
It encodes the viral transactivator protein. It binds to the viral genome and activates transcription.
The rev protein binds to the env gene to decrease splicing. TRUE/FALSE
TRUE. It encourages the reading of gag, pol and env to produce virions.
Why is it so difficult to develop a vaccine for HIV?
It possesses the ability to change its genome in a critical area. Infact, it has one of the highest error rates, leading to HIV strains resistant to zidovudine and other HIV medications.
It is estimated that 47 million persons worldwide have been infected with the HIV virus, and close to 14 million have died. TRUE/FALSE
TRUE.
Organisms such as Treponema pallidum, herpes simplex, Chlamydia trachomatis and Neisseria cause mucosal erosions and may even increase the concentration of HIV in semen and vaginal fluids. TRUE/FALSE
TRUE.
To reduce the risk of blood transmission, blood donors are screened for self reported risk factors and serologic markers. TRUE/FALSE
TRUE. This includes screening for antibodies to HIV-1 and HIV-2(Elisa) and for p24 antigen. Risk is reduced to 1/500,000.
What is the percentage risk of HIV transmission via a needle stick?
It is app. 0.3%. Hepatitis B from a positive patient is app. 30% and for Hep C. is app 3%.
What happens once HIV is in the blood?
Its gp160 glycoproteins bind to the CD4 receptor on target cells. This CD4 receptor is present in high concentration on T helper lymphocytes. These cells are referred to as CD4+T-helper cells.
What other cells possess CD4 receptors?
macrophages, monocytes and CNS dendritic cells(though in lower numbers)
How does the HIV virus bind to the CD4 receptor?
There are 2 cell surface cell proteins, "fusin and CKR5", that are produced by T lymphocytes and macrophages.
They serve as cofactors with the CD4 molecule for binding of HIV.
Patients who fail to produce normal levels of CKR5 proteins appear to be resistant to HIV infection and certain lymphocyte proteins. TRUE/FALSE
TRUE.
What happens to the viral RNA once in the cytoplasm?
The viral RNA is reverse transcribed into DNA in the cytoplasm. Double stranded DNA is formed and transported into the nucleus, where integration into the host DNA occurs.
The integrated DNA may lie latent or may activate to orchestrate viral replication.
There is some eveidence that certain infections may incite viral activation. TRUE/FALSE
TRUE. Tbc, PCP, Cytomegalovirus, herpes, Mycoplasma or immunizations may activate T cells and promote viral replication, within T cells.
What are the 3 specific stages of HIV?
1. Acute viral illness- fever, malaise, lymphadenopathy, pharyngitis. There are high levels of blood borne HIV.
2. Clinical latency- follows for a median of 8 years during which there are no symptoms. there is still a lymphadenopathy, and there is a steady gradual destruction of CD4 T lymphocytes(helper) cells. Cd4 + T helper cells are the primary target. patients become gradually more prone to infection.
3. AIDS develops for a median of 2 years followed by death. Aids is now defined as having a CD4 T lymphocyte count of less than 200(positive Elisa) Infections at this point include, candida esophagitis, Pneumocystis carinii pneumonia and Kaposi's sarcoma.