HIV Flashcards
How does the HIV virus infect the CD4 cell?
The target cell for HIV is the CD4 cell. The CD4 cell expresses three receptors on its cell membrane which are important to HIV.
What are the three receptors important to HIV?
CD4 receptor
The CCR5 receptor which is found on macrophages and dendritic cells
The CXCR4 receptor is found on Th cells.
Process of how HIV infects CD4 cell?
HIV gp 120 protein virus must bind with the CD4 cell and one of the other two receptors. Once bonded, the gp 12 protein will fuse with the CD4 cell. Once fused, the viral RNA will be injected into the cell cytoplasm. The viral RNA is then uncoated (capsid removed) and the enzyme reverse transcriptase is used to make DNA from the viral RNA. The enzyme integrase integrates the viral DNA into a host cell. Then, transcription and translation occur to make new viral proteins. The viral proteins then gather beneath the cell membrane and a capsid is formed around them. It then buds through the cell membrane and obtains a viral envelope. Viral maturation occurs after this.
What is the mechanism of the enzyme reverse transcriptase?
The enzyme reverse transcriptase is used to make DNA from the viral RNA of HIV
What is the mechanism of enzyme integrase in the HIV infection process?
The viral DNA travels to the nucleus of the cell where it is integrated into the host cell’s DNA using the enzyme integrase.
What is the process of viral maturation?
The process by which larger immature viral proteins are cleaved into smaller functional viral proteins by protease. The virus then leaves to infect more CD4 cells.
What happens to CD4 cells infected with HIV virus?
The infected CD4 cells will eventually rupture, undergo apoptosis, or be killed by other T cells. This causes a decrease in CD4 cell number which can cause AIDs. Without enough CD4 cells in the body, an immune response can not be initiated because this cell is the main cell that recognizes antigens and triggers the immune response. This leaves the host susceptible to opportunistic infections.
How do antiretroviral medications prevent HIV replication?
They prevent the action of all three HIV enzymes (viral enzyme HIV reverse transcriptase, HIV integrase, and viral enzyme HIV protease).
How can HIV progress to AIDs?
Having a CD4 count drop below 200, even if it comes back up and even if they have never had an opportunistic infection, the diagnosis stays the same.
What are the clinical signs of HIV?
- Thrush
- Cervical dysplasia
- Cervical carcinoma in situ
- Fever for greater than a month
- Oral hair leukoplakia
- PID
- Peripheral neuropathy
- Persistent vaginal yeast infections
- Kaposi Sarcoma
- Opportunistic infections
What is the 3rd generation immunoassay?
HIV EIA with western blot. The old gold standard test for HIV. Assesses for the presence of antibodies to HIV. The test can be completed with urine, saliva, or serum; however the most accurate is through serum. The two tests have a sensitivity of 99% 12 weeks post-exposure. The period between the 12 weeks is known as the window period. The EIA is the first test to be completed and if only that is positive, is the western blot test conducted. Both need to be positive for a positive HIV diagnosis.
What is the 4th generation immunoassay?
The gold standard for HIV testing. Detects antibodies to HIV and the presence of the p24 antigen which is a part of the HIV’s viral proteins. This can be detected as early as 10 days post-infection. This combined antibody and antigen test detected HIV early. If this test is positive–> HIV-1/HIV-2 antibody differentiation test is done–> if this is negative or indeterminate–> HIV viral load should be performed to clarify diagnosis
What is pneumocystis jiroveci pneumonia?
Pneumocystis jiroveci pneumonia is the most common opportunistic infection. The organism is a fungus. Signs include dyspnea that progressively gets worse over weeks. The patient will be fatigued with night sweats, weight loss, and have a poor appetite. A chest x-ray will reveal a butterfly pattern of infiltrates that extend from the center of the chest. Treatment is administration of Bactrim.
What are the three opportunistic infections?
- Pneumocystis jiroveci pneumonia
- Myobacterium avium complex
- Cytomegalovirus
What is mycobacterium avium complex?
Acid-fast bacillus that results in a systemic infection. Individuals experience fevers, night sweats, weight loss, and lymphadenopathy. Treatment is clarithromycin and ethambutol for 6-12 months. The long treatment period is due to acid-fast bacillus having a thick cell wall so nutrients and medications have a hard time penetrating this thick cell wall.
