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From Monkeys to Medicine

How Primate Research Advances The Fight Against HIV

June 6, 2026

What Is HIV, And Why Should We Care?

Human Immunodeficiency Virus (HIV) is a virus that infects the immune system. It can be transmitted through blood exposure, sexual contact, during birth, or through nursing. Left untreated, it can severely weaken a person’s immune system, leading to the development of Acquired Immune Deficiency Syndrome (AIDS), which makes the body vulnerable to serious infections by other pathogens and death. In 2024, an estimated 40.8 million people were living with HIV, with 1.3 million people newly diagnosed and 630,000 dying from AIDS-related illnesses that year (UNAIDS fact sheet). Since then, disruptions to global treatment and prevention programs, like the recent dismantling of USAID, have likely increased the number of new HIV infections and AIDS-related deaths, especially in vulnerable populations like children.

Is There A Cure For HIV?

No. Several medicines (known commonly as AntiRetroviral Therapy, or “ART”) have been developed that can help stop the virus from replicating in people with HIV. However, ART does not eliminate the virus, and when someone with HIV stops taking their ART medication, the virus can start replicating again within a few weeks and cause that person to become sick. This is because HIV is a retrovirus, meaning it inserts a copy of itself into infected cells, and if it stays silent, it can hide in these cells for decades. This pool of infected cells, which can be found throughout the body, is known as the HIV “reservoir” and is the major barrier to a cure. Furthermore, while ART dramatically enhances health outcomes and lifespan for people with HIV, it is common for people with HIV on ART to have health problems at a higher rate than people without HIV (including increased risk for cardiovascular, metabolic, aging, and neurological issues).

Some people have been cured of HIV after they received chemotherapy and a stem cell transplant that was intended to treat their advanced blood cancer. This is great news! However, other people have received similar treatments and have not been cured. Currently, these treatments are not ready to be used in people with HIV who do not have cancer requiring chemotherapy and stem cell transplant. Scientists don’t yet understand why these treatments are effective in some people and not in others, but they are working hard to find out. Monkeys are particularly valuable for these kinds of studies because they allow researchers to better understand (a) what is happening in different parts of the body and (b) to study different aspects of these treatments.

Why Are Monkeys Used To Study HIV?

HIV is closely related to a family of viruses, known as Simian Immunodeficiency Viruses (SIV), that are found in some monkey populations and are thought to be an ancestor of HIV. In some monkeys, SIV causes an infection that is very similar to what happens with HIV in people (including how the immune system responds to infection, where the virus is found in the body, and how the disease progresses to AIDS). In other monkeys, SIV does not cause serious illness and studying them could provide insight into how people might be able to fight off HIV. Because monkeys also have an immune system and anatomy that is very similar to humans, scientists can use SIV in monkeys to study:

  • How HIV infection occurs in people and why it persists during ART
  • How HIV infection can be prevented in people
  • How HIV might be cured in people

Can We Replace Monkeys With Other Experimental Systems?

HIV is a virus that infects different cells across different parts of the body, including cells in lymph nodes, spleen, bone marrow, liver, gut, and brain. The biology of each of these tissues (including differences in the immune system found in each) can be very distinct and can have a significant impact on HIV. These are complex and interconnected systems, which makes replication in simple laboratory models difficult. Scientists who study HIV use a variety of experimental approaches, including computer models, in vitro cell cultures, animal models (e.g. mice and monkeys), and clinical trials in humans; these can all add to our understanding of HIV biology, but they are not interchangeable. For instance, experiments done in petri dishes may tell us whether a prospective drug candidate may be interesting to pursue, but they will not tell us whether a drug is safe or effective in people. On the other hand, a clinical trial testing a new treatment might not always have a clear outcome because the important interactions between immune cells, HIV, and medicines occur in tissues that are difficult to assess in people. Monkey research is important for developing new approaches for understanding and treating HIV, and without it, the HIV research field would advance at a much slower pace.

How Are Scientists Using Monkeys To Study HIV Today?

Some ways in which monkeys are used to study HIV include:

  • HIV prevention
    • Development of vaccines and antibody treatments that can prevent HIV infection
    • Development of more effective Pre-Exposure Prophylaxis (PrEP)
  • HIV pathobiology
    • Understanding how HIV persists for years during ART across the entire body
    • Developing new types of ART (including longer-acting and more effective versions)
    • Understanding and treating health problems experienced by people with HIV (including cardiovascular and neurological issues)
    • Characterizing and treating the impact of co-infections (such as HIV with tuberculosis, malaria, and cancer-causing viruses like Epstein-Barr)
  • HIV treatment and cure
    • Targeting clearance of HIV during ART using treatments ranging from chemotherapy-like pills and antibodies that trigger HIV-infected cells to die to engineered T cell therapies (CAR-T), which hunt down HIV-infected cells throughout the body.
    • Helping the immune system to fight HIV using treatments ranging from immunotherapy (using antibody infusions) to therapeutic vaccines.

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