‘Resistance’ occurs when the medicines you might be taking for your HIV disease can’t stop the virus from making more copies of itself—a process known as replication. Resistance is caused by the way HIV makes new copies of itself. If you aren’t being treated for your HIV disease, it can make billions of new virus particles every day.
But that replication process isn’t perfect. HIV multiplies so quickly that it makes a lot of mistakes in the new copies. If these imperfect copies of the virus are able to go on to create copies of themselves, they are known as mutations.
Mutations are good for viruses—but they can be bad news for people living with HIV. That’s because HIV medications may not work on mutations. We say that HIV is “drug-resistant” when it can multiply quickly in your body, even though you are taking medications to stop that from happening. The ability of HIV to mutate and reproduce itself in the presence of antiretroviral drugs is called HIV drug resistance (HIVDR). The consequences of HIVDR include treatment failure, need to start more costly second- and third- line treatments, increased health costs associated with these, spread of drug resistant HIV, and need to develop new anti-HIV drugs.
HIV medicines that previously controlled the person’s HIV are not effective against the new, drug-resistant HIV. In other words, the HIV medicines can’t prevent the drug-resistant HIV from multiplying. Drug resistance can cause HIV treatment to fail.
Drug-resistant HIV can be passed from one person to another. There are two types of resistance tests. Drug-resistance testing is done to identify which, if any, HIV medicines won’t be effective against a person’s strain of HIV. Drug-resistance testing is done using a sample of blood.
The best way to prevent resistance is to keep HIV from replicating. If it isn’t reproducing, the virus can’t mutate and make new strains of HIV that are drug-resistant. That’s what antiretroviral drugs do—they keep HIV from reproducing. And that’s why it’s important to take all your HIV medications on time and consistently. When you do that, your medications can do a better job of keeping the virus under control and keep it from mutating into strains that won’t respond to treatment.—Adapted from www.aids.gov