Why Is Your Resistance to HIV Drugs Rising?

A high number of people with HIV are showing resistance to both newer and older drugs, a surprising turn according to findings publshed in the journal The Lancet Infectious Diseases. 

Drug reistance occurs when a disease develops a way to respond to medicine being used to treat it. According to a 2012 Centers for Disease Control and Prevention report, two out of every 10 new cases of HIV involve strains with at least partial resistance to one or more antiretroviral medication. Those with a strain of HIV resistant to the three classes of drugs generally available in antiretroviral therapies are rarer, representing less than one percent of new HIV diagnoses.  

This particular study involved at 712 people with HIV strains that aren't being controlled by drugs used to treat the disease today. The surprising result was that 16 percent of the participants turned out to be resistant to older drugs called thymidine analogues, which the participants had never taken.  

It was previously known that multi-drug resistance can occur, and that people could be resistant to a whole class of drugs even if they'd only been exposed to one medication in that class. In addition multi-drug resistant strains of HIV can be transmitted, which may help explain why some participants in this study had a strain resistant to both modern and older drugs, even though they'd never taken those earlier therapies.  

Lead author and Professor of Infection and Immunity at University College London, Ravi Gupta says to prevent these multi-drug resistant strains from spreading further, the global HIV community needs more HIV monitoring. 

“We need cheap, reliable systems to assess people before treatment," Gupta explained in a University College London news release. "Ideally, we need simple resistance testing kits to help screen for drug resistance before giving treatment. This would also help us to monitor HIV drug resistance globally more effectively."

Those kinds of tests are standard practice in the U.S., because they help determine the kind of treatment someone with HIV should be prescribed. Lab testing can be expensive and time consuming which may prohibit their use on a global scale.  

Gupta argues there's another way, saying, "until such kits are widely available, we could test the amount of virus in the bloodstream before and after giving treatment. Although not as precise as resistance testing, this could help us to detect treatment failure earlier and switch patients to second line drugs."

While new medications, like the long-acting injectable Ibalizumab, offer promise in fighting multi-drug resistant HIV, those are typically second-line treatment given to people who’ve become resistant to first-line drugs. Other alternatives are seldom available to those living in rural areas, which is why Gupta says it’s important to focus on preserving the effectiveness of first-line treatments. 

"We were very surprised to see that so many people were resistant to both drugs, as we didn't think this was possible," explained Gupta. “Mutations for thymidine analogue resistance were previously thought to be incompatible with mutations for tenofovir resistance, but we now see that HIV can be resistant to both at once. This emphasises  the need to check the genetic profile of patient's virus before prescribing first-line treatments, as they may have already developed resistance to other treatments that they did not mention having taken."