A KILLER CURE
TAKING THE STING OUT OF HIV
If a swarm of killer bees decides to attack you, run. Keep running and don’t stop. These nasty blighters can sting a man to death. Ironically, their venom could also help save millions by helping to rid the world of HIV. Guest writer Janske Nel explains how on page 19.
It is a blazingly sunny December afternoon in a small town at the southern tip of Africa. The air is hot and heavy. No wind or breeze stirs the tree tops. Sara, a mother of two, is working in the garden, meticulously uprooting weeds, pruning hedges, and trimming the trees covering her perfectly pink hydrangeas. Suddenly, the air around her is filled with a droning, angry sound as a black cloud rises up from the tree foliage. Instinct takes over, and Sara covers her face and runs. Adrenaline and panic temporarily keep the pain at bay, but the multiple stings she receives from a swarm of African honey bees – or killer bees as they are known in most parts of the world – demand to be felt eventually. The intense pain seizes her; she collapses, and darkness descends. Little does she know that what’s coursing through her veins, and could be killing her, could hold a cure for a disease that is decimating her beloved country.
The murderous helper
In South Africa, the legends and myths surrounding the beautifully coloured goldenyellow and black striped stingers are passed down through the generations: a horde of thousands of bees will relentlessly chase you for almost half a kilometre once the nest is disturbed, and the venom from between 500–1100 stings can kill an adult human. Venoms like those of the African honey bee, are cocktails of substances that can have a harmful effect on the human body, the ingredients of each cocktail being unique to each species of venomous creature. For many venoms there are no anti-venoms (more correctly called ‘antivenins’) available. However, an ongoing revolution in medical research is looking past the need to develop antivenins to focus instead on the therapeutic properties of the venoms themselves: what if venom-toxins could be used to cure instead of kill? This is not a new idea. The great 15th century philosopher Paracelsus once said; “In all things there is poison; there is nothing without poison. It only depends upon the doses, whether a poison is a poison or not”. So, over the years, hundreds of venoms have been studied for their potential therapeutic effects, with some of the most deadly venoms providing the most potent treatments. Since 1974, researchers have been exploring the anticancer potential of venoms from snake species such as the Elapidae family (which include Cape and Egyptian cobras), Viperidae family (rattlesnakes), and Crotalidae family (pit vipers). Toxin from Agkistrodon contortrix (the copperhead snake) has been shown to reduce the spread of tumours, while the purified venom from the Tasmanian tiger snake has been found to slow the growth of neuroblastoma cells (tumours of the head and brain). Currently, purified venom-toxins from snakes are used in drugs for high blood pressure, strokes, kidney diseases, diabetes, heart failure, and even deafness – as well as being used as anaesthetics. Amphibian skin also carries fascinating venoms that can be used to heal wounds, kill cancer cells, and destroy microbes – with the latter being the subject of particularly fervent research given the rise of microbes that are immune to most currently-available antibiotics. Bee, wasp, centipede and scorpion venoms have also been tested for their ability to effectively treat leukaemia, liver cancer and multiple sclerosis; and as treatments to destroy the bacteria associated with sexually transmitted diseases such as chlamydia, and candida infections.
Zooming in on a cure for HIV
But the use of venoms as the basis of potential medicines isn’t without major challenges. After all, venoms – by their very nature – are meant to kill. To unlock the healing power of venoms a way must be found to cross the line from toxin to therapy. And this is where the fields of nanomedicine and nanotechnology are stepping up to the challenge.
Nanotechnology is a field of research that works with particles at the nanoscale – objects sized between 1 and 100 nanometres (1 nm = one billionth of a metre). To put this into perspective, an atom is 0.1 nm wide, viruses are between 10–100 nm in size, and the diameter of a human hair is a bulky 100 000 nm. Nanomedicine, the field of research that develops nanoparticles for use in medicine, has as one goal: the design of drug delivery systems that are safer, easier to control, and more effective than traditional medicines. It is here that venom and nanotechnology are coming together in a harmonious relationship that could drastically improve human lives, especially in South Africa. South Africa is a country amongst those with the highest rates of HIV/Aids in the world. It is estimated that over five million South Africans have so far contracted the virus – a staggering 10% of the country’s overall population. Thousands of kilometres away, at the Washington University School of Medicine in the US, researchers have turned to bee venom to try and find a solution to the rapid spread of HIV. Their weapon of choice: nanoparticles coated with a highly potent toxin from bee venom called melittin. Melittin isn’t a complete newcomer to the world of medicine: it is already known to be an anti-cancer agent, capable of attacking renal, lung, liver, ovarian, prostate, bladder, and breast cancer. Its effect comes from its ability to destroy cell membranes, causing cells to rip apart. (This also explains why a bee sting is so unpleasant!) It may come as little relief to Sara and the thousands of other people who are injured and killed by bees every year, but the marriage of venom – feared by mankind for millennia – and nanotechnology, a small but ever-growing field, could have a revolutionary effect on our ability to fight diseases that kill millions. Perhaps countries like South Africa, which are home to the most venomous creatures, should re-evaluate how they look at their buzzing, slithering, scuttling and scary neigh - bours – not as mortal enemies, creatures that bring and power to heal.
but as the potential
Spatial foraging patterns and colony energy status in the African bee A lytic peptide with anticancer properties Cytolytic peptide nanoparticles (‘NanoBees’) for cancer therapy. Cytolytic nanoparticles attenuate HIV-1 infectivity Anti-cancer effect of bee venom toxin and melittin in ovarian cancer cells through induction of death receptors and inhibition of JAK2/STAT3 pathway Bee venom in cancer therapy Nanoparticle-conjugated animal venom-toxins and their possible therapeutic potential