-- HIV Diversity: Subtypes and Resistance --

>HIV exists in multiple groups and subtypes (clades): The most common in the U.S. and Europe is HIV-1, Group M, subtype B, but globally there are many other subtypes (A, C, D, F, G, H, etc.) and even HIV-2, which is more common in West Africa and less susceptible to some medications.

>Drug resistance mutations (DRMs) can develop in people with HIV who are on suboptimal or failing treatment regimens, or who acquire a resistant strain from another person. This is where your memory of people with HIV potentially needing to change their regimen after exposure to another strain comes in — it's still very relevant today.

-- PrEP Today: Truvada, Descovy, Apretude --

>None of these protect against HIV-2.

>All are vulnerable to failure if the virus has pre-existing resistance to one or more components, which is rare in prevention, but not impossible (e.g., FTC-resistant HIV).

-- HIV Treatment Still Requires Customization --

>Once infected, HIV treatment (ART) is never one-size-fits-all. Resistance testing (genotype) is often done before or shortly after starting therapy. Some key points:

>Treatment-experienced individuals may carry multi-drug resistant strains (MDR HIV), requiring tailored regimens.

>Superinfection (being infected with a second strain of HIV while already positive) is rare but possible, and could complicate management if the new strain is resistant.

>Lenacapavir, fostemsavir, and ibalizumab are part of a new generation of treatment options for multidrug-resistant (MDR) HIV, not standard for PrEP/PEP.