It sounds like something out of a sci-fi saga, but it’s true, scientists have found a gene mutation that protects against HIV, and it traces back to ancient humans from around 9,000 years ago. The same mutation later appears in Viking-era DNA, raising questions about how it spread, and why it still matters.

The gene is called CCR5-Δ32. If you have it, you’re partly or even fully resistant to certain strains of HIV. And while HIV didn’t exist back then, the mutation might have helped ancient people survive other deadly infections. That advantage may be why it stuck around.

Now, researchers are looking at this gene not just as a historical curiosity, but as a clue in ongoing HIV research and treatment. [Cell, 2025] So what do Vikings, viruses, and modern medicine have in common? Let’s break it down.

What is CCR5-Δ32 and how does it protect against HIV?

CCR5 is a protein found on the surface of white blood cells. HIV uses it like a door to get inside the body’s immune cells. Without access to this doorway, the virus struggles to spread.

The Δ32 mutation changes the CCR5 protein. It makes the door incomplete, so HIV cannot get through. People with one copy of the mutation have some resistance. Those with two copies are highly resistant to certain strains of HIV.

This mutation does not protect against all types of HIV. But it is a big deal. It explains why some people can be exposed to the virus many times and still test negative. It also helped researchers understand how HIV enters the body and how to block it.

In fact, this mutation played a role in the only known cases of HIV being cleared from the body. Two patients received bone marrow transplants from donors who had the CCR5-Δ32 mutation. After the transplant, the virus could not return. [PNAS, 2023] These were not cures in the usual sense, but they showed what is possible.

Where did this gene come from?

Scientists believe the CCR5-Δ32 mutation began in a population near the Black Sea between 6,700 and 9,000 years ago.  [ScienceDaily] That part of the world has seen a lot of human migration, trade, and conflict over the centuries, so it makes sense that something important in our DNA could have started there.

The mutation probably became more common because it offered protection, not from HIV, which didn’t exist yet, but from other deadly diseases like smallpox or plague. People who had the mutation were more likely to survive and pass it on. Over time, it spread through parts of Europe.

By the Viking Age, around 800 to 1100 CE, the mutation was found more often in Northern Europe, especially in Scandinavia. Some researchers think the Vikings helped carry it further, as they travelled and settled in parts of the British Isles, France, and even Russia. [Live Science, 2025] Today, the mutation is most common in people of Northern European descent.

What does this have to do with HIV today?

Even though the mutation came long before HIV, it’s become a key piece of HIV research. Scientists first noticed it in people who had been exposed to the virus but didn’t get infected. That led to studies on how the CCR5 protein works and how blocking it could stop HIV.

This is where it gets interesting. Two men, known as the Berlin Patient and the London Patient, received bone marrow transplants from donors with the CCR5-Δ32 mutation. After the procedure, the virus disappeared from their bodies. It did not come back. These were rare and complex cases, but they showed what might be possible in future treatments.

Now, researchers are trying to find safer ways to use the same idea. Some are testing gene-editing tools to copy the CCR5-Δ32 effect. Others are developing drugs that block the CCR5 protein. The goal is not just to treat HIV, but to give people long-term protection or even a functional cure.

Can you be tested for this gene?

Yes, there are genetic tests that can check for the CCR5-Δ32 mutation. These tests are not part of standard HIV screening. They are usually done for research or as part of personal genetic reports.

Knowing whether you have the mutation does not mean you are fully protected. It only works against certain strains of HIV. Even people with two copies of the mutation are not completely immune to all forms of the virus.

So while the gene is useful in research, it is not something most people need to test for. The best way to stay protected is still the usual advice: use condoms, get tested regularly, and consider PrEP if you are at higher risk.

What ancient genes tell us about the future of HIV

The CCR5-Δ32 mutation is a reminder that our history lives in our DNA. A gene that may have helped people survive smallpox thousands of years ago is now helping us understand HIV in the present.

It also shows that useful traits can spread over time and leave a mark across generations. The mutation travelled, survived, and now offers clues that could lead to better treatments or even a future where HIV can be controlled without daily medication.

Science is not about quick fixes. It builds on what came before. Sometimes that includes ancient genes from people who never imagined HIV or understood what DNA was. But they passed down something that matters. And now it’s helping researchers look ahead.

In the meantime, we already have tools that work. Regular testing, early treatment, and prevention options like PrEP make a big difference. If you want to learn more or speak to someone, Shim Clinic is here to help.