 |
How
Virus Works How our knowledge helps us combat a deadly virus. |
| Below
you will find Illustrations on how HIV virus attacks the cell and how
medications work. |
|
 |
The CD4+ cell ( sometimes called a T-helper cell) is a white blood cell that is a part of our immune system, which helps us fight infection. |
 |
HIV attacks these cells and turns them into HIV factors. As HIV copies are manufactured, the CD4+ cells are effectively destroyed over time. |
 |
Once inside the CD4+ cell, the HIV's single strand RNA (red coil )uses an enzyme ( e ) known as "reverse transcriptase" to convert HIV RNA into double strand DNA. |
 |
The HIV DNA ( red-blue double coil ) moves into the nucleus of the CD4+ cell, where it becomes part of the CD4+ cell's own DNA. |
 |
Once HIV DNA is in the nucleus, it takes over the CD4+ cell and instructs the cell to produce more HIV virus, which are sent out to infect more CD4+ cells. |
 |
HIV attacks both activated CD4+ cells which have been "turned on" and are dividing and actively fighting infection. |
 |
And resting CD4+ cells which have not encountered any infection and are waiting to be called into action. |
  |
While both activated and resting CD4+ cells are attacked by the HIV, activated cells reproduce the virus faster and in greater amounts. |
 |
Drugs know as "nucleoside analogues" (NA) bind the RNA of the HIV virus and interfere with the DNA building process. The virus begins to produce its DNA, but the viral DNA is incomplete and unable to make new copies of the viruses. |
 |
Some nucleoside analogue drugs such as Zerit ( stavudine, d4T ) and Retrovir ( zidovudine, AZT ) are known as thymidine analogues. Thymidine analogues ( NA ) are more effective in activated CD4+ cells. |
 |
Non-Thymidine nucleoside analogues ( NA ) such as Videx ( didanosine, ddI ), Hivid ( zalcitabine, ddC ) and Epivir ( Lamivudine, 3TC ) are more effective in resting CD4+ cells. |
 |
Another class of antiretroviral agents is called " non-nucleoside reverse transcriptase inhibitors" ( NNRTI ). This class stops HIV production by attaching itself to the reverse transcriptase enzyme. As is true with the nucleoside analogues, this also prevents conversion of HIV RNA into DNA. NNRTI are Viramune, ( nevirapine ) and Rescriptor ( delaverdine ). |
 |
Protease Inhibitors ( PI ) such as Invirase ( saquinavir methylate ), Crixivan ( indinavir ), Norvir ( ritonavir) and Viracept ( nelfinavir ) work at the final stage of the virus reproduction cycle - just as the copies of the viruses are about to depart from the original CD4+ cell, to infect other cells. There drugs prevent the HIV copies from being successfully assembled and released to do their damage. |
| Who
should consider having an HIV test? HIV infection and AIDS are not the same thing. How does the HIV testing work? Are there benefits to being tested? |
Test
results - What do they mean? Questions and answers. Know Where You Stand Back to Main Page |
