drugs that are no longer effective

[em]

I am sure if I check this might have been asked before. but I am curious if anyone might know ?  When they test for drug resistance to the virus .  Is it the virus or the body that becomes resistant to the drug?   The body can no longer process the drug or the immune system becomes unable to process that med ? If someone gets a different strain of the virus from someone who stops their meds .  Do they then become resistant to all the meds the new virus has already been exposed too ? 

Just curious about the bug I carry   

[Jim Allen]

Hiya,

It's not the body that becomes resistant, it's an HIV mutation.
https://www.poz.com/basics/hiv-basics/hiv-drug-resistance

If someone gets a different strain of the virus from someone who stops their meds

This is a question for the "How do I prevent HIV" section, but in short, there is not much chance of that happening. Added a few links to previous threads on the topic for you.

https://forums.poz.com/index.php?topic=74805
https://forums.poz.com/index.php?topic=68615
https://forums.poz.com/index.php?topic=65688

[leatherman]

When they test for drug resistance to the virus .  Is it the virus or the body that becomes resistant to the drug? 

There are two types of test to test resistance:
1. A genotype test measures whether the HIV in your blood sample reacts to your meds. This test is used to see if the meds you are taking are still effective.
2. A phenotype test measures which drugs affect your HIV. This test can help determine what drugs are available to use against your HIV.

Resistance (HIV mutating to resist a medication) mainly happens from not taking enough meds properly. The amount of virus has to drop to low levels, but not be totally absent, for the virus to mutate against the drug. In other words, someone who takes meds a few days, then skips a few, then takes it for a few more days sets themselves to have the levels of meds dip too low and HIV mutating before bringing the levels back up. Completely stopping meds usually doesn't cause resistance because the level of meds continue to drop well past any level to effect HIV before the HIV can mutate.



I took this chart from a site about antibiotics and edited it a little bit, so please ignore any weirdness there at the 2nd dose. The thing to take away is that any time adherence falls below the point (the red dashed line) of keeping the med level high enough (at least 95% adherence or higher*), resistance becomes possible.

*Thankfully, the meds of today are much more effective. With a longer half-life (the amount of time the med is at the right level in your system), these meds stay in our systems longer, making incidents of non-adherence (skipping a dose) less likely to allow HIV to mutate. This is what allows a greater leeway (2-4 hrs) around the timing of each day's dose, or not developing resistance when missing a single dose in a month.

If someone gets a different strain of the virus from someone who stops their meds .  Do they then become resistant to all the meds the new virus has already been exposed too ? 

yes. If a non-infected person is infected by someone whose HIV has mutated to resist some medications, the newly infected person's HIV will also be resistant to those medications.

however, someone who is already HIV+ cannot be "reinfected" with a resistant strain of HIV unless in a few very rare circumstances as mentioned in those links Jim provided. The two dudes in the hospital with AIDS (both stopping meds, both sick, both with high viral loads and resistance issues) having the where-with-all, and the ignorance, to have unprotected sex is certainly astounding and a very rare circumstance.

here's a good write-up about resistance from the San Fran AIDS foundation
https://www.sfaf.org/collections/beta/heres-what-you-need-to-know-about-hiv-drug-resistance/
and more info from poz.com
https://www.poz.com/basics/hiv-basics/hiv-drug-resistance