Does PrEP Protect Against the Newly Discovered HIV Variant?
Researchers have discovered a variant of the human immunodeficiency virus (HIV) in the Netherlands that they say spreads faster and progresses quicker in the body than other HIV strains.
But despite the more virulent effects of this particular strain—which the researchers refer to as "VB" in their Feb. 3 article in the journal Science—existing HIV treatments work just as well on the new variant, scientists behind the study say.
Based on the available evidence, it's also likely pre-exposure prophylactic (aka PReP) drugs are equally effective at protecting HIV-negative individuals from the VB strain, according to Christophe Fraser, one of the researchers involved in the project.
Christopher Brown, 55, a long-time PrEP user, said he's not worried about the newly discovered HIV strain.
Brown began taking the prophylactic HIV drug a little over six years ago when he re-entered the dating pool after a divorce. Since then, he's dated two different men with HIV and had a few sexual encounters with other HIV-positive individuals. Today, Brown continues to take PReP in order to have unprotected sex with his HIV-positive boyfriend of two years. He's confident that PReP will continue to provide adequate protection against infection.
"I really do feel protected," Brown said.
How VB is different
While the discovery is recent, the VB variant itself isn't new. The first confirmed sample comes from 1992, which researchers said suggests the virus emerged sometime in the late 1980s or early '90s. So VB has been circulating around the Netherlands for several decades, but cases have been in decline since 2010, according to a press release from BEEHIVE, the Oxford data project behind the discovery.
The Oxford study notes that VB is a "highly virulent" strain of HIV. Untreated, VB is much more infectious and progresses to advanced HIV and AIDS much faster than other variants.
HIV virulence describes the degree to which the virus invades and multiplies within its hosts. Virulence is often measured in viral load, the quantity of a particular virus found in a fluid sample from an infected individual. HIV researchers also look at CD4+ cell count to determine the damage the virus caused to the immune system.
In patients infected with the VB variant, CD4+ cell decline was double the expected rate, and the viral loads were about three to four times higher than other strains.
Individuals infected with this newly discovered strain were vulnerable to developing AIDS within two to three years, according to the study. By contrast, other strains typically progress to AIDS in 10 years or more without treatment, according to the National Institute of Health.
How the strain reacts to PrEP and treatment
Fortunately, the HIV treatment options that emerged around the mid-'90s appear to work just as well on individuals with the VB variant, reducing transmission and the chance of developing a more severe illness.
"After starting treatment, individuals with the VB variant have the similar immune system recovery and similar survival to individuals with other HIV variants," the press release read.
Based on this one study, researchers can't say with absolute certainty that PReP remains equally effective against the newly discovered strain, according to Chris Beyrer, a professor of epidemiology at the John Hopkins Bloomberg School of Public Health.
The majority of the samples in the Oxford study are from before 2012, Bryer said, the year the FDA approved the first PReP drugs.
Moreover, the data contained samples from individuals but not their sexual partners, meaning the research couldn't definitively answer questions around transmission—including exactly how well PReP protects against VB compared to other variants.
"The transmissibility question, you can't really ask from these data," said Beyrer.
But there are several strong reasons to believe that PReP remains effective, he continued.
In "study after study" viral load has proven a very effective indicator of transmissibility—the lower the viral load, the less contagious the infected individual.
"People with higher viral loads are more infectious or their sex partnership, but treatment has worked to bring down the viral load in these people [with the VB variant]," said Beyrer. "And, of course, if you are fully treated and virally suppressed you are not infectious for your sex partners."
And while much of the data predates PReP, the prophylactic was developed from the same drugs used in earlier HIV treatments, according to Fraser. Because those treatments worked on VB, it's likely PReP would also continue to work just as well against the more virulent variant.
"There is good reason to believe PrEP will be exactly as effective as usual for the VB variant, because treatment worked as well as usual and PrEP is based on the same drugs for suppressing the virus," Fraser wrote in an email.
Finally, researchers did not observe any known mutations associated with drug resistance in the VB variant that would make it less susceptible to treatment, added Lucie Abeler-Dorner, another co-author on the study.
No Cause for Alarm...Yet
Researchers emphasized that the newly discovered variant shouldn't cause any worry in the public.
"The worst-case scenario would be the emergence of a variant that combines high virulence, high transmissibility, and resistance to treatment," the press release read. "The variant we discovered has only the first two of these properties."
But the existence of a more virulent strain of HIV—one that spreads faster and damages the body quicker—emphasizes the importance of widely accessible HIV testing and treatment, researchers wrote. Early diagnosis and immediate treatment can limit the spread of this and all strains of the virus, and lead to significantly brighter health outcomes for HIV-positive individuals.
The VB variant does serve as an important reminder that viruses—even those that, like HIV, are over 100 years old—can still mutate into deadlier and more infectious forms. Mutations are particularly common for the "highly variable" retrovirus HIV, said Beyrer.
Luckily, in the arms race between HIV researchers and the virus itself, medical science appears to be on top for now.
"The good news is that our therapeutic options just keep getting better,'' Beyrer said. "We have lots and lots of antiviral drugs...so far anyway, they all work against all the known variants including this one."