If the pandemic taught the world nothing else, it's that viruses can mutate, potentially giving rise to new and more harmful variants.
Now, new research reveals that's exactly what has happened with HIV, the virus that causes AIDS.
Called VB (for virulent subtype B), the "new" HIV variant actually seems to have emerged more than 30 years ago. But its existence was only recently confirmed by a team of genetic researchers from the United States, the United Kingdom, the Netherlands, France, Sweden, Germany, Switzerland and Finland.
That it has largely flown under the radar may reflect the fact that the VB variant has only been found in 109 HIV-positive patients so far, most of them Dutch. But although not widespread, the concern is that -- absent preventive treatment -- the variant seems to attack a patient's immune system much more aggressively than more common strains.
Even so, study author Chris Wymant, a senior researcher in statistical genetics and pathogen dynamics with the University of Oxford's Big Data Institute, is adamant that "the public needn't be worried."
For one thing, he noted that while there may be more VB-infected patients than is currently known, the number is "unlikely to be dramatically higher than what we found." The 109 patients already identified are not, Wymant said, "the tip of the iceberg."
And most critically, existing antiretroviral therapies (ART) remain very effective at keeping the VB variant at bay.
So, the real value of this discovery is to re-emphasize "the importance of [the] guidance that was already in place -- that individuals at risk of acquiring HIV have access to regular testing to allow early diagnosis, followed by immediate treatment," Wymant explained.
"This limits the amount of time HIV can damage an individual's immune system and jeopardize their health," he noted. "It also ensures that HIV is suppressed as quickly as possible, which prevents transmission to other individuals."
In the Feb. 4 issue of Science, Wymant and his colleagues described how the new variant was first discovered through the ongoing efforts of the so-called BEEHIVE project.
BEEHIVE was launched in 2014 in recognition of the fact that "HIV mutates so quickly that every individual has a virus which is different from everyone else's," Wymant said, though he stressed that, as a practical matter, "the large majority of these mutations make no difference."
But Wymant pointed out that among those not already on a one-pill-a-day ART regimen, HIV seems to affect patients "in a remarkably variable way."
"Some progress to AIDS within months," he noted, "while others do not progress after decades. Some have viral loads -- levels of virus -- thousands of times higher than others. [And] research by our team, and others before the BEEHIVE project, established that this variability is partly due to the virus, not only due to people's immune systems varying in their ability to fight the virus."
So, the BEEHIVE scientists set out to continuously monitor incoming data from seven different HIV studies across Europe and Africa, with the goal being to identify and track any viral changes that might significantly alter the way a virus that has already claimed 33 million lives behaves.
Enter the VB variant, which was initially identified in just 15 patients in the Netherlands, one in Switzerland and one in Belgium. A subsequent deep dive into the viral underpinnings of more than 6,700 HIV-positive patients unearthed another 92 VB-infected patients.
The investigators found that patients infected with the VB variant had HIV viral loads amounting to 3.5 to 5.5 times higher than would be found in patients infected with other known variants. The VB variant was also found to be much more transmissible.
And absent treatment, the team observed that, on average, VB-infected patients in their 30s progressed to "advanced HIV" in just nine months. That is much faster than is typical among those infected with other variants, said Wymant, with older patients likely to experience even quicker disease progression.
Why? Because of a far faster drop in the patient's CD4 cell count, a key marker for immune system damage.
Still, the good news is very good: once VB-infected patients are put on antiretroviral therapy, survival rates were just as strong as with any other HIV variant. And while acknowledging that even more deadly variants may eventually surface, Wymant noted that, so far, "this is an example of something that thankfully seems to be rare."
The main message is that "we need to ensure timely HIV diagnosis and rapid provision of antiretroviral drugs," agreed Joel Wertheim, an associate professor in the department of medicine at the University of California, San Diego.
"Viruses are constantly evolving," Wertheim noted. "The COVID-19 pandemic keeps reminding us of that in real-time."
That means that "HIV testing is as important as ever," he stressed. "If people don't know they've been infected, they can't take the precautions needed to limit transmission. This is true regardless of HIV variant, and doubly so where this more virulent variant has been observed."
Visit the U.S. Centers for Disease Control and Prevention for more on HIV.
SOURCES: Chris Wymant, PhD, senior researcher, statistical genetics and pathogen dynamics, Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield department of medicine, University of Oxford, U.K.; Joel Wertheim, PhD, associate professor, department of medicine, University of California, San Diego; Science, Feb. 4, 2022