Molecular snippets hold viruses at bay

In a surprising find, scientists have uncovered the antiviral properties of an obscure class of peptides that may someday provide a powerful way to curb the spread of sexually transmitted diseases.

Led by professor of ophthalmology and medical microbiology Curtis Brandt, the team of UW–Madison researchers discovered that several so-called membrane transit peptides – parts of certain protein molecules with a special ability to traverse membranes – prevent cell infection by three major STD-causing viruses: herpes simplex virus, papilloma virus and HIV.

Brandt originally investigated the transit peptides as a means to usher other promising, but poorly penetrating, antiviral molecules across the plasma membrane into cells.

“But we never got that far,” he says, “because it turns out that the membrane-transiting peptides themselves are antivirals. This is an excellent case of scientific serendipity.”

The peptides are synthetic but are based on natural transit peptide sequences from diverse sources, including the fruit fly Drosophila and HIV itself. Although Brandt hasn’t determined their precise mode of action, the peptides seem to interact directly with virus particles to permanently inactivate them.

Transit peptides could eventually be added to contraceptive products, such as vaginal creams and foams, to prevent STD infection. Although they wouldn’t provide 100 percent protection, their use could drop the incidence of viral transmission dramatically, says Brandt, giving women a needed alternative to sole reliance on a partner’s use of a condom. And unlike many current compounds, which often work only against specific viruses, the broad-acting peptides could block all three major STDs at once.

Brandt and his collaborators recently received a major grant from the National Institutes of Health to develop the peptides as a topical treatment for preventing STDs. He has applied for a patent on the technology through the Wisconsin Alumni Research Foundation, a nonprofit organization that manages the intellectual property of the UW–Madison.