Whilst screening the National Cancer Institute’s extract repository, scientists discovered a new class of proteins from a feathery coral found in Australian waters. It transpires that these proteins, called cnidarins, are in fact potent inhibitors of HIV entry into T-cells in laboratory tests.

At a time when over 35 million people worldwide are infected with HIV and current treatments are not curative, focusing on the prevention of new infections is paramount in confronting this global problem. HIV has also presented significant challenges in the development of vaccines and none are so far available.

Although condoms are effective at preventing transmission, the fact is: not everybody uses them, and often this is out of the control of some individuals. The development of other methods that can curb sexual transmission are therefore an attractive solution to the problem, and scientists believe that these cnidarins may eventually be used to do just that.

After discovering these proteins, scientists purified them and tested them for inhibitory effects against laboratory HIV strains. They found that they prevented HIV from being able to enter T-cells at impressively low concentrations. T-cells are one of the main cells that HIV targets for replication. The proteins achieved this block by binding to the virus and preventing fusion with the host cell, which is a pre-requisite to viral entry.

Before the scientists can proceed with preclinical tests to find out more about the safety and efficacy of these proteins, they first need to find a way to mass produce these proteins without having to harvest vast quantities of corals.

Although it is certainly very early days, the scientists are optimistic that these proteins may present an ideal candidate for the development of topical gels or lubricants that could prevent sexual HIV transmission without encouraging resistance, which is a problem that current antivirals face.

This study also serves as an exciting reminder for the fact that many natural substances with surprising medicinal properties may await discovery. “The natural products extract repository is a national treasure,” said Barry O’Keefe, senior investigator of this study. “You never know what you might find. Hopefully, discoveries like this will encourage more investigators to use this resource to identify extracts with activity against infectious disease.”