A breakthrough study of nearly 800 gay male couples found that antiretroviral drugs stop the transmission of HIV from an infected partner to an uninfected partner – even during unprotected sex.

European researchers found no cases of HIV virus transmission during the eight-year prospective observational study of 782 different couples, meaning one partner was HIV positive and the other was HIV negative. The couples did not use condoms.

The researchers concluded that, with the drugs, the HIV virus, which leads to AIDS, could not be passed on through unprotected sex.

"Our findings provide conclusive evidence for gay men that the risk of HIV transmission with suppressive ART [antiretroviral drugs] is zero," said Alison Rodger, according to Reuters.

Rodger, a professor at University College London who co-led the research, called the findings a "powerful message" that could help end the HIV pandemic by preventing HIV transmission among high-risk populations.

Since the 1980s, more than 77 million people have contracted the HIV virus and nearly half of those have died of AIDS, according to Reuters.

The National Institute for Health Research funded the study published Thursday in The Lancet medical journal.

What is ART?

ART therapy is a combination of drugs combined in a pill that prevents the HIV virus from replicating itself in the body, according to News Medical.

The medication doesn't cure HIV but it can reduce the viral load in the body making it undetectable.

Did any of the study participants get HIV?

Fifteen new HIV infections occurred among the study participants.

But none of the screened viruses in the newly infected partner was genetically linked to the virus that infected their main partners.

What did other experts say?

The study "adds to the clear and consistent evidence" that ART therapy suppresses the virus and blocks its transmission, Rachel Baggaley, the World Health Organization's coordinator for HIV prevention and testing, told the outlet.

"Increasing access to HIV testing (and) ART ... remains critical for individuals and is central to the HIV public health response," Baggaley added.

Dr. Ford Hickson from the London School of Hygiene and Tropical Medicine told News Medical that the study proves patients who suppress their HIV through ART "cannot pass their virus to other people during sex, whatever kind of sex they have."

What else?

The researchers estimated that ART therapy prevented 472 HIV transmissions during the study.