Can strains be resistant/stronger than PrEP

[Guest]

So a few weeks ago I considered getting back on PrEp and I did I have been on PrEP  again for 4 days now and yes I take daily PrEP (one pill a day). But It has made me wonder can strains be resistant to PrEP or if i got bred by a guy with a severely high vl strain could I still get infected 

[BootmanLA]

It is definitely possible for a particular strain of HIV to become PrEP-resistant. This apparently occurs mostly when people are spotty about taking PrEP (meaning the level in their systems becomes inadequate to prevent infection), become infected without realizing it, and continue to take PrEP for months until they're tested again.

The reason is that while adequate blood levels of the two medications in PrEP are generally sufficient to repel HIV infection, they are insufficient, by themselves, to treat HIV infection. As a result, the infection continues to burrow into the newly infected person, with some of the HIV killed off by the PrEP medication, but not all - and what remains is are mutations that are least susceptible to PrEP's medications. Those mutations become the dominant type in that individual.

That said, those cases are rare. Not unknown, but rare.

As for "severely high vl strain" - there's no such thing, technically.

"Severely high viral load" refers to the number of virus particles per given quantity of blood used for the test - in other words, it's a countable thing. 

"Strain" refers to a variation in the genetic makeup of the virus - in other words, it's a qualitative thing.

One can have a high viral load of a drug-resistant strain (rare), a high viral load of an easily treatable strain (e.g. most people shortly after infection), a low viral load of a drug-resistant strain, or a low viral load of an easily treatable strain (including most undetectable guys on treatment).

It's true that you if you compare infection odds between bottoming for a guy with a high viral load of a drug-resistant strain, on the one hand, and bottoming for a guy with a low (or undetectable) viral load of a treatable strain, your chances of infection are much higher in the first case. But since you can't do viral load tests for your partners every time you have sex, that's kind of a roll of the dice.

One thing's for sure: you're far less likely to get infected if you're taking PrEP, regardless of the details of the HIV status of your partner. If you take it daily, without exception - or at least, if your occasionally missed dose doesn't overlap with risky sexual activity (a missed dose isn't a big deal if you haven't had sex in a week and aren't going to have sex for another week), the odds of infection are infinitesimally small.