Australasian Science Magazine

By Stephen Luntz

Vampire bats could be good for the heart, with their venom showing potential against high blood pressure, according to research published in the Journal of Proteomics by A/Prof Bryan Fry of the University of Queensland.

Vampire bats are one of four mammalian lineages to have developed venom, along with platypus, water shrews and slow lorises. While many reptiles and invertebrates produce venom for the purpose of killing their prey, bats just want the blood to flow more freely so they can gain a lot in a short amount of time.

“The venom has three functions,” says Fry. “It blocks the coagulant cascade in multiple ways, it dilates the small arteries under the skin and it has an anaesthetic effect so the animal being fed on doesn’t shake the bat off.

Fry says his team has yet to identify the anaesthetic molecule. However, in exploring the anticoagulants they learned that the bat uses not only multiple compounds but many slightly different versions of each.

“This means that even if an antibody is generated against one molecule, there are a number of others that will sneak past the prey’s defence system and keep the blood flowing,” Fry says. “This means the same victim can be fed on night after night.”

The three species of vampire bats have differences in their venom to reflect the common vampire bat’s mammalian diet, while the other two species prefer birds. While Fry has compared their venoms, the venoms that are most effective on humans hold the most interest.

Novel drugs based on natural venoms could prove useful in the fight against heart disease, says Fry, because “they may be longer-lasting or more specific than existing blood pressure drugs. High blood pressure can have many different causes and we may need different drugs for different causes.”

Fry says that vampire bat venom shows more promise in this regard than venom from snakes because the venom has a “non-lethal but very specific role”. One consequence is that many of the proteins are smaller. “Below a certain size peptides are invisible to the immune system,” Fry says.

Despite their reputation, bats usually take sufficiently small amounts of blood from their prey that they would do little damage, although Fry adds that they are also a major reservoir for rabies.