HIV Flashcards
What virus causes HIV infection?
A Lentivirus, genus Retroviridae, single stranded RNA
What is the binding site for CD4 cells?
Envelope protein GP 120
What occurs at the cellular level in HIV infection?
Helper cells are damaged. They normally are responsible for presenting antigen to B cells and stimulating them with cytokines as well as cytotoxic T cells.
IL1 secretion is reduced as well as chemotaxis and cytotoxicity,
How does HIV enter the body?
Via dendritic cells inn the vagina and surface lymphatics.
What is the role of reverse transcriptase?
It permits the viral RNA to enter the nucleus of the immune cells and become part of the cells’ DNA. Replication of the immune cells results in production of the HIV RNA which kill the immune and other cells. Inflammation worsens the process.
What time period is required for HIV dissemination throughout the entire body?
One week.
How long does it take to destroy the immune system?
8 to 10 years.
How many CD4 cells are destroyed daily?
200,000,000,
How many virions are destroyed/ cleared daily?
10,000,000.
What does ART(combination of multiple drugs) do?
It blocks viral replication, resulting in a change in the balance of replication and destruction. The result is and increase in CD4 cells, then memory cells and finally naïve cells.
What are the opportunistic infections (OI) in Africa?
CNS Cryptococcosis, TB, Esophageal Candidiasis, PCP, Amebiasis, CMV Retinitis, CNS Toxo
What are the OI in developed countries?
PCP, Esophageal Candidiasis, MAC Infection, CMV Retinitis, CNS Cryptococcosis, CNS Toxo
At what CD4 count level do the above OI appear?
CD4 of 200 or less
At what CD4 level does Bacterial Pneumonia and Orall Thrush appear?
CD4 count between 500 and 200
What is the treatment for PCP? If sulfa allergic
TMP-SMX3 to 4 X per day, if sulfa allergic use escalating doses of TMP-SMX
When is Prednisone used?
if hypoxic with PaO2 <70, Tapered over 20 days
What infections are frequently concomitant ?
PCP and TB
How does an infection with Toxoplasmosis occur?
Usually from reactivation of oocysts ingested from undercooked pork, lamb and beef
What is the treatment of Toxoplasmosis?
Pyrimethamine + Sulfadiazine + Folinic Acid; steroids are not helpful
When do you suspect disseminated Cryptococcal infection?
When CD4 ct is less than 100
What are the sx of CNS infection?
Progressive severe HA with stiff neck
What physical findings are associated with this infection?
6th nerve palsy due to elevated ICP
Molloscum like skin lesions
Non inflammatory Meningitis