Defence Peptide May Block Transmission

No Entry: Retrocyclin may block
HIV transmission;© PHIL

HIV-1 often mutates quickly to overcome antiviral compounds designed to prevent infections. But a research team led by Associate Professor Alexander Cole of University of Central Florida´s (UCF) Burnett College of Biomedical Sciences has demonstrated that over 100 days the virus develops only weak resistance to retrocyclin, a defence peptide still found in monkeys and lower primates.

There are three classes of defensin peptides, and most research around the world has focused on alpha and beta defensins, the two types that humans still make. Cole studies theta-defensins called retrocyclins, which are no longer made by humans or advanced primates such as chimpanzees. However, theta-defensins are more active against HIV-1 than the other two types of defensins and can be developed in laboratories, two features that suggest retrocyclins still could become an effective way to fight the virus.

The exact reason why resistance does not develop quickly with retrocyclin is unclear, but it may be a result of the peptide interacting with more than one target on both the cell and virus. Viruses that have to defeat more than one antiviral mechanism often develop resistance at a much slower pace.

Cole is also working with Henry Daniell, a UCF professor of molecular biology and microbiology, to develop a way to grow retrocyclin through genetically engineered tobacco plants. The retrocyclin gene would be incorporated into the chloroplast genome of tobacco cells before the plants grow. An inexpensive way to produce the drug would help to make it accessible in areas such as Southeast Asia, Africa and the Caribbean where the disease spreads most quickly.

If additional laboratory tests demonstrate only weak resistance, Cole will study how retrocyclin could be developed into a drug designed to prevent the HIV virus from entering human cells.; Source: University of Central Florida