Coral reefs yield new proteins to tackle HIV
National Cancer Institute researchers have discovered a new class of protein found in sea coral that appears able to prevent HIV from entering T cells. If the proteins can be adapted for use in sexual lubricants and gels, they could offer a new form of barrier against HIV infection.
The study findings featured at the Experimental Biology 2014 meeting in San Diego on 29 April.
Senior investigator Dr. Barry O'Keefe, deputy chief of the Molecular Targets Laboratory at the Center for Cancer Research at the National Cancer Institute (NCI), says:
"It's always thrilling when you find a brand-new protein that nobody else has ever seen before. And the fact that this protein appears to block HIV infection - and to do it in a completely new way - makes this truly exciting."
The team discovered the proteins while screening thousands of natural product extracts in an NCI biological repository. Belonging to a class called cnidarins, the proteins were found in feathery corals collected from the sea off the north coast of Australia.
The new proteins do not trigger resistance to other HIV drugs
Co-investigator Dr. Koreen Ramessar, an NCI research fellow, says the cnidarins can block HIV without making the virus resistant to other HIV drugs, making them ideal for inclusion in anti-HIV microbicides, for which there is a pressing need. Women can use anti-HIV gels and lubricants without having to rely on a man being willing to use a condom.
Dr. O'Keefe says, "even if the virus became resistant to these proteins, it would likely still be sensitive to all of the therapeutic options that are currently available."
Cnidarins have 'unique mechanism of action' against HIV
After purifying the proteins, the team tested them on lab strains of HIV. They found them to be remarkably potent. Even at concentrations as low as a billionth of a gram, the proteins could block HIV and prevent the first step in the virus' transmission where it penetrates T cells in the immune system.
The cnidarins appear to bind to the virus and stop it fusing with the membrane of the T cell. Dr. Ramessar says this is "completely different from what we've seen with other proteins, so we think the cnidarin proteins have a unique mechanism of action."
Belonging to a class called cnidarins, the proteins were found in corals collected off the north coast of Australia.
The team now plans to improve ways to produce the proteins in larger quantities so they can be tested more extensively, for instance to find any side effects or if they might work against other viruses.
Dr. O'Keefe says this will be an important step, commenting that "you can't strip the Earth of this coral trying to harvest this protein."
The team found the proteins in the NCI's large repository of natural product extracts, which collects natural specimens from around the world with the consent of their countries of origin. The repository is available to scientists across the US.
Dr. O'Keefe describes the NCI repository as a "national treasure," where "you never know what you might find."
He says he hopes news of discoveries like this one will encourage more scientists to use the repository.
In November 2013, Medical News Today learned how another study led by Swansea University in the UK and reported in the journal Nature Materials suggested bone grafts may be better with new sea coral material. The small trial in 16 patients found refining sea coral into coralline hydroxyapatite/calcium carbonate made it more compatible and degradable for use in bone grafts than a currently used derivative.
Written by Catharine Paddock PhD
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