Tasmanian Devil’s Milk

Just last week, there was some exciting news coming out of Australia that milk from a very unlikely source may be a weapon in the desperate and ongoing battle against superbugs.

According to Australian researchers at Sydney University, Tasmanian devil’s milk can help destroy many of the most feared and deadly fungal and bacterial infections that we know about.

The Tasmanian devil is a small carnivorous marsupial found only on the Australian island state of Tasmania. Unfortunately, the animal has become endangered because of disease epidemics and estimates put their current numbers at between 20 and 50,000.

Like most marsupials, the Tasmanian devil delivers its young in a very under-developed stage. In the case of the devil, they are born after just 21 days of gestation which is the equivalent of a human baby being born after just 7 weeks’ gestation.

Because of this, scientists have speculated that the mother’s milk must play an important role in the development of their offspring’s immune system. But the researchers were certainly not expecting to make the discoveries that they did.

After scanning the Tasmanian devil’s genome, researchers at Sydney university discovered six antimicrobial peptides which they then tested against harmful bacteria some of which were among the most dangerous known to man. (1)

It is estimated that unless a treatment is found, superbugs may kill as many as 10 million people each year from the year 2050. There is a growing desperation to find a treatment that is not resistant to conventional antibiotics.

One member of the research team – Emma Peel admitted that she was very excited about the results. She noted that the study had showed that Tasmanian devil’s milk could effectively destroy multi drug resistant bacteria. “it was really exciting” she said.

Included among the frightening drug-resistant bacteria killed by the peptides in devil’s milk was golden staph otherwise known as Methicillin resistant staphylococcus aureus. MRSA is a potentially lethal form of bacteria carried by around 30% of humans in their skin or their nose.

Fortunately, it is generally harmless but when the bacteria finds its way into the bloodstream through a wound, the trouble starts and it can prove fatal.
The peptides also proved effective against a very dangerous bacterium known as enterococcus. This bacterium has even proven to be resistant to the very potent antibiotic – vancomycin.

According to Ms Peel:

‘Vancomycin is a very potent antibiotic and if a bug is resistant to it, then there are not a lot of other drug options available to you’

The results of the research were the culmination of a three-year study and have drawn justifiable levels of excitement from the medical community and the media.

They are significant because these results might just pave the way for new drugs to be developed – drugs that may just prove priceless in the global war against drug-resistant superbugs.

Margaret Chan, the Director general of the WHO recently described bacterial resistance as a “fundamental threat to human health, development and security”. Estimates of the catastrophic effects of such superbugs make for scary reading.

Many experts suggest that if they are left unchecked, they could cause more death than cancer within the next 3 or 4 decades. If those estimates are correct, it means that some 10 million people each year will be killed by superbugs.

The peptides found in Tasmanian devil’s milk come from an antimicrobial family known as cathelicidins. These cathelicidins have a natural antibiotic effect and are naturally occurring throughout the animal kingdom. While we humans have only the one, the Tasmanian devil is blessed with six types of them.

Summary of the Study

As was already mentioned, the researchers identified six cathelicidins. Two of those cathelicidins called Saha-CATH5 and Saha-CATH6 exhibited a broad spectrum of antibacterial activity. These two cathelicidins were capable of killing several very harmful human pathogens including MRSA and E.faecalis both of which are multi-drug resistant strains of bacteria.

Saha-CATH3 exhibited activity against fungi. The other three cathelicidins did not prove to be active against the bacterial and fungal strains they were tested against. However, they were expressed widely through the body including the digestive tract, the respiratory tract and the reproductive tracts as well as in the immune tissue.

This seems to indicate that they are an essential part of the Tasmanian devil’s natural immune system.

The results of the study are strong evidence that cathelicidins play a crucial role in protecting the offspring of the Tasmanian devil during its early days in the pouch.

This research has built on previous studies into marsupial milk. It was already known that marsupials carried a diverse range of peptides. Some species of wallaby have eight varieties while the opossum has as many as 12.

These peptides have a powerful antimicrobial activity which helps baby marsupials known as joeys to fight against harmful bacterial and fungal invasion while they are allowed to develop in the not so sterile mother’s pouch. A study conducted in 2015 found that there was a diverse variety of bacteria thriving inside the pouch of the Tasmanian devil.

According to Ms. Peel it was this fact which inspired the study. The fact that there were so many pathogens present in the devil’s microbiome and yet the offspring did not become sick was a definite clue that there was something of interest going on.

Other Marsupials Milk

This study is not the first time that marsupial milk has been recognized for its medicinal potential to humans. In 2011, team of scientists from Melbourne, Sydney and Monash Universities were surprised to find that the Tammar wallaby milk contained a whopping 14 different peptides opening the way for antibacterial drugs which could combat many of the dangerous drug resistant strains.

They had actually begun their research into wallaby milk because of its high protein content compared to cow’s milk. They were looking for a way to improve the nutritional value of cow’s milk. Their findings certainly took them in another direction.

As in the case of the Tasmanian devil, these peptides protect the tiny under developed offspring from infection during their time in the pouch. The researchers noted that the bacteria in the wallaby pouch was similar to the type that notably infects humans during hospital stays.

Working backwards, the researchers led by Professor Ben Cocks used a bio-computational system to recreate the wallaby gene which codes the peptides. They then synthesized the genes in the lab.

The research team, who also found 8 peptides in the milk of the platypus, discovered that the peptides in wallaby milk was spectacularly effective against bacteria that had proven resistant to most antibiotics.

One particular peptide that they studied appeared very early on during lactation and was highly effective against drug resistant bacterial strains. In fact, the peptide proved to be as much as ten times more effective than standard antibiotics such as ampicillin and tetracycline.

Similar studies are now being conducted with koalas and preliminary results have showed that similar peptides are present in koala’s milk. Australia is a country with a large number of different marsupials, all of which would have evolved to protect their young from a host of pathogens in a variety of very differing environments.

According to Kathy Belov, a geneticist at Sydney University,

“There has to be a treasure trove of amazing peptides out there to be discovered.”
(1) http://www.nature.com/articles/srep35019