References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
HIV is a lifelong infection because the virus inserts its genetic material into the DNA of long-lived immune cells, creating a hidden reservoir that current treatments cannot reach. Even when antiretroviral therapy reduces the viral load to undetectable levels, these latently infected cells persist — silently carrying HIV DNA for years or decades. If treatment is stopped, the virus reactivates from this reservoir.
Here’s why this happens and what it means.
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How HIV Gets Into Your DNA
HIV’s life cycle includes a step called integration, where the virus converts its RNA into DNA and inserts it into the host cell’s chromosomes. Once integrated, the viral DNA becomes part of the cell’s genetic code. When the cell divides, the viral DNA is copied along with everything else.
The Latent Reservoir
| Feature | Detail |
|---|---|
| What it is | A pool of resting CD4 cells carrying integrated HIV DNA |
| Where it hides | Lymph nodes, gut, brain, bone marrow and other tissues |
| How long it lasts | Decades — the half-life of the reservoir is estimated at over 40 years |
| Can ART reach it? | No — ART only stops actively replicating virus |
| What happens if ART stops | Latent cells reactivate, viral load rebounds within 2-4 weeks |
Why ART Can’t Eliminate the Reservoir
ART works by blocking the enzymes HIV uses to replicate. But the latent reservoir isn’t replicating — the cells are resting, with HIV DNA sitting silently in their chromosomes. Because there’s no active viral process to block, ART has no effect on these cells.
Why the Reservoir Matters for Cure Research
Eliminating or permanently silencing the reservoir is the main challenge in HIV cure research. Current strategies being explored include:
- Shock and kill — wake up latent cells so the immune system or drugs can destroy them
- Lock and block — permanently silence the latent virus so it can never reactivate
- Gene therapy — edit out the integrated HIV DNA using tools like CRISPR
- Therapeutic vaccines — train the immune system to control HIV without ART
What This Means For You
If you’re living with HIV on effective treatment:
- Your treatment is keeping the virus suppressed — it’s working
- The reservoir means treatment must continue for life
- U=U still applies — you cannot pass HIV on sexually when undetectable
- Research is actively working on ways to tackle the reservoir
- Modern ART gives you a near-normal life expectancy
Read more: Can HIV be cured? | HIV and the immune system | Gene therapy for HIV
Frequently Asked Questions
Not if you’re on effective ART with an undetectable viral load. The reservoir doesn’t produce enough virus to be detectable or transmittable while treatment is working.
Will the reservoir shrink over time?
Very slowly. The reservoir does decline on ART, but its half-life is so long (40+ years) that it’s unlikely to disappear naturally within a lifetime.
Why can’t my immune system clear the reservoir?
Latently infected cells look identical to normal resting CD4 cells. The immune system can’t distinguish them from healthy cells.
Related reading
- A to Z of Sex: Sexual Health Terms Explained
- Alcohol and HIV: What You Need to Know
- Anxiety and HIV: Coping and Getting Support
- Are All STIs Curable?
- Blood Problems and HIV: Anaemia, Low Platelets and More
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
