A new study published in eBioMedicine
, part of the medical journal The Lancet, has found that about 4% of people who had HIV in the Democratic Republic of Congo were naturally able to suppress the virus without taking medication.
It has raised the hopes of finding better ways to control HIV, which disproportionally affects women in sub-Saharan Africa.
A lead scientist, Dr Mary Rodgers, told the BBC the group was the biggest detected in one country.
She said understanding how it was able to maintain low or undetectable viral loads would be crucial to controlling the epidemic, but more research was needed.