In The Spotlight | What are broadly neutralising antibodies and what do they mean for the fight against HIV?

HIV is known for its ability to outsmart our immune system’s normal defences. A small number of people living with the virus are however able to generate unusually effective immune responses. In this special briefing, we zoom in on broadly neutralising antibodies (bNAbs), the secret sauce in these immune responses, and their potential role in the future of HIV treatment and prevention.

Our immune systems are highly effective at identifying and fighting off foreign invaders, such as viruses. One way our immune systems does this is by producing antibodies. In short, antibodies recognise viruses and then latch on to them. This blocks the viruses from entering our cells and flags them for destruction by other parts of the immune system.

One of the most remarkable things about our immune system is that it is able to create an enormous variety of such antibodies tailored to each different virus and other disease-causing pathogen that we encounter over our lifetime.

The human immunodeficiency virus (HIV), however, outsmarts our bodies’ normal immune responses by constantly changing the parts of its surface that antibodies recognise. This makes HIV difficult for antibodies to attach to and neutralise.

After several years of living with HIV, some people are able to produce a special type of antibody, known as broadly neutralising antibodies, or bNAbs. These antibodies are more effective at neutralising HIV than regular antibodies because they recognise parts of the virus that change very little, known as ‘conserved regions’. By targeting parts of the virus that are less prone to change, bNAbs are more effective than regular antibodies in identifying and neutralising the constantly changing virus.

“About 20 percent of people living with HIV naturally develop bNAbs, after many years,” explains AVAC, a US-based NGO seeking to advance the development of HIV prevention tools. “By the time bNAbs have developed in these individuals, the constantly mutating HIV has outpaced these defenders, changing too fast and too significantly for bNAbs to be effective in that individual. But that same bNAb, or a combination of them, may work in someone else,” they say.

Researchers first identified bNAbs in a person living with HIV in the 1990s. Since then, they have discovered many more bNAbs and papers and presentations on the topic have become a staple at HIV conferences. At the 2026 International AIDS Conference held in Rio de Janeiro, Brazil, in July, there were 21 abstracts related to the topic.

Since the 1990s, researchers have learned how to replicate and produce bNAbs in the lab. They have conducted early-stage trials showing that bNAbs can be safely administered to people and they have learned how to engineer bNAbs to increase their potency and make them last longer in our bodies.

SA’s LATEST HIV NUMBERS ARE IN | 7.9 million people are living with HIV. Treatment coverage has crept up by just 40 000. And 53 000 HIV-related deaths were recorded.