resistance and reuse
Dec 21, 2011
hello doctor, i have one question regarding resistance. suppose after several years of 1st regimen use due to selection pressure NRTI and NNRTI resistant virus becomes majority. Then protease inhibitor combo is started as 2nd regimen. In this scenario all the NRTI and NNRTI resistant population dies. Then can we use the first regimen again after several years of use of 2nd regimen? Thank u for ur time doctor....
Response from Dr. McGowan
Thanks for your great question.
Even though we kill off all of the growing virus with our medicine combinations we cannot stop taking the HIV meds and have to always remember which drugs the virus had become resistant to in the past.
This is because HIV inserts copies of its genes into the chromosome (genes) of the CD4 cell. CD4 cells are part of our immune system and protect us against infections. Some of the CD4 cells have to survive and persist for many years, they are called "Memory Cells". They have Memory of past infections such as chicken pox (Varicella) or past vaccinations that we have had. If we ever get exposed to chicken pox again, these memory cells wake up and protect us. Without them we would get measles over and over again, etc. So if HIV inserts its genes into these memory cells (which it does), then its genetic code will stay asleep inside of these cells until they are "woken up" (stimulated) by the infection that they recognize. If there is no effective medicine in the blood to suppress it, the virus from these cells will restart the entire HIV infection over again. Also resistant virus, even from many years ago, will be present in these cells and can re-emerge if the old drugs are restarted.
Hope this helps explain it.
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