Scripps Research Institute scientists report that a naturally occurring peptide, defensins, known for its antibacterial action can also inhibit viral infection. They say that two forms of human a-defensins, expressed in epithelial cells of the small intestine, the female genitourinary tract, and air passages, had potent antiadenoviral activity in cell culture.
When added at the beginning of a 60-minute viral incubation period, defensins achieved 96% adenovirus inhibition at very low concentrations, the investigators explain. At higher doses, defensins reportedly stopped virtually all viral infection activity.
The Scripps team explains that the defensins blocked infection by binding to and stabilizing the virus capsid and preventing partial uncoating of the virus, which marks the start of the infection process. “Defensins inhibit the release of an internal viral protein called pVI, which is required for endosomal membrane penetration during cell entry,” says Jason Smith, Ph.D., first author of the study. “This results in an accumulation of infectious virions in intracellular endosomes and lysosomes, where they are eventually destroyed. This is the first time this mechanism has been identified.”
The study will be published in the January 17 edition of Cell Host & Microbe.