Understanding the human body is a team effort. That's where the Yachtel group comes in.

Researchers at Yachtolt have been delving into the secrets of probiotics for 90 years. Yacold also

partners with nature portfolio to advance gut microbiome science through the global grants for

gut health, an investigator-led research program. To learn more about Yachtold, visit yacolt.co.com.j, that's Y-A-K-U-L-T.

C-O.J-P. When it comes to a guide for your gut, count on Yacol.

This is Scientific American 60-second science. I'm Cynthia Graber. Got a minute?

They were thought to have great promise in the fight to stop the spread of AIDS.

Indeed, vaginal microbicides did a fine job killing HIV in the lab, but they failed to work in clinical trials.

Now, researchers think they have identified the culprit, semen.

In previous studies, scientists had looked

at the HIV virus on cells protected by microbicides. But the latest tests evaluated

microbicides in the more real-world situation where semen is present. And semen stopped the

microbicides from working, probably because semen contains protein fragments that help HIV

to attach to cell surfaces and infect cells.

The research is in the journal Science Translational Medicine. There's good news, though,

a drug not currently used as a microbicide did seem to offer protection. It's an antiretroviral

called maravirac. Conventional microbicides target the virus itself, but Maravirok binds to receptors on host cells.

That action forms a barrier that prevents the HIV virus from attaching to the cell.

Maraviric is currently approved as an HIV drug and is being considered as a microbicide to try to stop infection in the first place.

The research is a reminder that, in drug testing, context is crucial.

Thanks for the minute. For Scientific American 60 Second Science, I'm Cynthia Graver.