Investigators at Vanderbilt University Medical Center reported this month in the Journal of Virology that compounds secreted by frog skin are potent blockers of HIV infection.
The findings could lead to topical treatments for preventing HIV transmission, and they reinforce the value of preserving the Earth's biodiversity.
"We need to protect these species long enough for us to understand their medicinal cabinet," said Louise A. Rollins-Smith, Ph.D., associate professor of Microbiology & Immunology, who has been studying the antimicrobial defenses of frogs for about six years. Frogs, she explained, have specialized granular glands in the skin that produce and store packets of peptides, small protein-like molecules. In response to skin injury or alarm, the frog secretes large amounts of these antimicrobial peptides onto the surface of the skin to combat pathogens like bacteria, fungi and viruses.
Rollins-Smith happens to have the laboratory next door to Derya Unutmaz, M.D., associate professor of Microbiology & Immunology. During a hallway chat one day, the two decided it would be interesting to investigate whether any frog peptides have activity against human viruses, specifically HIV, the focus of Unutmaz's group.
Postdoctoral fellow Scott E. VanCompernolle, Ph.D., screened 15 antimicrobial peptides from a variety of frog species for their ability to block HIV infection of T cells, immune system cells targeted by HIV. He found several that inhibited HIV infection without harming the T cells.
The peptides appear to selectively kill the virus, perhaps by inserting themselves into the HIV outer membrane envelope and creating "holes" that cause the virus particle to fall apart, Unutmaz said.
"We like to call these peptides WMDs -- weapons of membrane destruction," Unutmaz said. It is curious that the antimicr