Over 80% of HIV infections are acquired through sexual intercourse, primarily via semen from HIV-positive men. Pilcher says that researchers have been studying the role of semen in HIV transmission, but have focused primarily on the quantity and type of virus contained in semen. "We’ve looked at everything except the semen itself," he says.

Now researchers have found that peptides clustered together into long fibres may be more important for HIV transmission than viral load. “If that’s true, then we’ve been looking at the wrong thing for a long time,” says Pilcher.

They key would be to figure out how to prevent the fibres from binding with HIV and there by making men with HIV less infectious. There is still much work to be done in this area, but this is a promising new option in figuring out how to reduce the rate of HIV infection.