In the midst of a human pandemic, we have some good news about a wildlife one: our new research, published today in Science, shows Tasmanian devils are likely to survive despite the infectious cancer that has ravaged their populations.
Tasmanian devils have been devastated by a bizarre transmissible cancer. Devil facial tumour disease, or DFTD for short, was first detected in 1996 in northeast Tasmania. Transmitted via biting, DFTD has spread over almost the entire state, reaching the west coast in the past two or three years. It has led to a decline of at least 80% in the total devil population.
Ten years ago, we thought there was a real chance DFTD would drive the Tasmanian devil to extinction. Our concern arose not just because the cancer was almost inevitably lethal, but also because the transmission rate did not appear to slow down, even as devils became very rare.
Our new research has some good news: by pioneering application of genomic analysis typically used for viruses, we have discovered the curve has flattened and the rate of increase of infections has slowed. This means while the disease is probably not going away, neither are Tasmanian devils.
Genomics is a relatively new field of science that uses the vast amounts of data available from modern genetic sequencing techniques to answer some of the most difficult and important questions in biology.
The genomic approach we used is called phylodynamics. It uses sophisticated mathematical analysis of small changes in DNA to reconstruct the evolution and spread of the tumour through devil populations. This is the same method used to track the COVID-19 pandemic, and it was first developed to study the influenza virus. Viruses have small genomes and evolve rapidly. This is the first time the method has been used for a pathogen with a much more complex and slowly evolving genome.
Screening more than 11,000 genes, we found the R number (the average number of secondary cases for each primary case, now familiar from COVID-19) has fallen from about 3.5 at the peak of the epidemic to about one now. This suggests some sort of steady state has been reached, and the disease and devils are now coexisting.
This discovery backs up a paper we published last year, in which we reached a similar conclusion using mathematical models based on marking and recapturing Tasmanian devils at a single study site, without taking genetics into account.
Our new study is based on samples collected across Tasmania since the early 2000s. Given the very different nature of the two methods, the agreement between the results lends us increased confidence in our conclusions.
This paper, in addition to several we have published recently, shows there have been rapid evolutionary changes in Tasmanian devils and in the tumours themselves since the emergence of this transmissible cancer. Already, frequencies of gene variants known to be associated with immune function in humans have increased in Tasmanian devil populations, suggesting the devils are evolving and adapting to the threat.
We also now know a relatively small number of genes has a large influence on whether devils become infected, and whether they survive if they do.
Finally, and perhaps most encouragingly of all, we have now seen tumours shrink and disappear — something that was unheard of when the disease first emerged. What’s more, we also know this has a strong genetic basis, again suggesting the devils are genetically adapting to their foe.
Together, all of these discoveries show wild Tasmanian devils can evolve very rapidly — over just five generations or so — in response to this disease. This has profoundly encouraging implications for their likely future survival.
There is still much more to learn about the evolution of the devils and their tumours. But meanwhile, our results provide a warning that a strategy of reintroducing captive-reared animals to supplement diseased wild devil populations is likely to be counterproductive.
When devils from populations that have never been exposed to the disease interbreed with wild animals in diseased populations, the evolution we have seen in wild populations is likely to slow down or even reverse, endangering those populations.
What’s more, the slowing rate of disease transmission may be partly a consequence of reduced devil population densities, resulting in fewer bites. Artificially boosting population densities might accelerate disease transmission, the opposite of the intended effect.
With the growing body of evidence showing extinction of devils is quite unlikely even over the next 100 years, we have time for careful consideration of management strategies. Specifically, models can be developed to assess the evolutionary and epidemiological consequences of reintroductions or translocations.
One possibility would be to captively breed devils that have the right genes to boost their chance of surviving the disease. More broadly, our research underlines the vital importance of taking evolutionary considerations into account when managing endangered species. We now have the genomic tools to do so.
Many thanks to Andrew Storfer at Washington State University, Menna Jones and Rodrigo Hamede at the University of Tasmania, and Paul Hohenlohe at the University of Idaho for their contributions to this article and the research it describes.
A desperate rescue effort is underway after hundreds of long-finned pilot whales (Globicephala melas) became stranded in Macquarie Harbour on Tasmania’s west coast.
Yesterday, more than 250 pilot whales were reported to have stranded, with one-third presumed dead. And this morning, rescuers found another 200 pilot whales stranded up to ten kilometres away from the first group — most are likely dead.
This brings the total number of stranded pilot whales in Tasmania to more than 450, and it’s believed to be the biggest ever recorded in the state. The Greens are calling on federal Environment Minister Sussan Ley to launch a national response.
The rescue mission aims to refloat the pilot whales that appear to still be in reasonable health. But their behaviour hampers rescue efforts: many pilot whales re-strand themselves to be with their family. This event likely means a number of generations of the local population will be lost.
Do whales attempt suicide?
Despite its name, the long-finned pilot whale is actually a large oceanic dolphin. They cover vast areas of the Southern (Antarctic) Ocean, reaching between four and six metres in length and weighing up to one tonne.
They are well adapted to deeper oceans where they hunt for various species of squid in depths of between 600-1,000m, using echolocation to find their prey. Echolocation is a way of using sound to navigate in complete darkness.
They generally spend most of their lives offshore and it’s not well understood what conditions drive them close to shore, and to enter shallow embayments.
Some theories suggest food shortages are to blame, or changes in electromagnetic fields that disorient them. They may also be following a sick or distressed pod leader. And in some past cases strandings were related back to active sonar from ships and naval sonar interrupting their echolocation.
What causes whale mass strandings?
But once in shallow waters, it’s difficult to swim back out. As these whales mostly navigate with echolocation it’s not possible for them to use sonar effectively in shallow and muddy embayments.
It’s extremely distressing for the whales, a lot like trying to find the door in a dark room while hearing your relatives scream for help.
In fact, the stress is what many die from in the end. Other causes of death are overheating from sun exposure and drowning if they can’t move their bodies up to breach the surface in shallow water.
There are a number of strategies to refloat whales. In Macquarie Harbour, rescuers are using slings to tow the whales to deeper water, before releasing them.
Other options include multiple people pushing them off the beach during high tide into deeper water.
In this case, albeit potentially dangerous for the helpers, people power can make a big difference. After all, time is of immense importance for success, and to stop more whales beaching.
However, chances of survival plummet with long exposure to sun and extended periods of stress. What’s more, Macquarie Harbour is relatively remote and difficult to access, further complicating rescue efforts.
But the biggest obstacle rescuers face is the whales’ social bonding. Long-finned pilot whales are highly intelligent and live in strong social units.
So when dealing with mass strandings, it’s important to realise the emotions and bonding between the whales are very likely beyond what humans can feel. One well-documented example of their emotional depth is the pilot whale seen carrying its dead calf for many days.
This makes the stranding process extremely complex, as it unfolds over several hours to several days — the whales don’t all strand at the same time.
The situation for pilot whale pods can be similar, but more complex as a result of having much larger pods. Pilot whale pods have multiple sub-units, which can consist of friends as well as family and they don’t have to be genetically related.
Social units get mixed up when they’re in shallow bays. This means individuals can become disconnected from their social units before the actual stranding occurs, causing stress and confusion prior the beaching.
There are an estimated 200,000 long-finned pilot whales in the Southern Ocean and Antarctica, but mass strandings like this can have a profound impact on sub-populations.
In Tasmania alone, 1,568 long-finned pilot whales have stranded between 1990 and 2008 in 30 stranding events.
To make matters worse, studies suggest the long-finned pilot whales in the Southeastern Pacific have low genetic diversity. There are similarities between this species found in Chile and New Zealand, but with surprisingly distinct differences between New Zealand and Tasmania.
Considering they can live up to 50 years and the fact only few survive when multiple generations strand, such events not only destroy entire generations but also remove them from the gene pool.
This puts local populations at further risk. Inbreeding is one consequence, but the biggest problem is their decreasing general fitness and ability to adapt to changes.
In the past, significant numbers of stranded whales have been successfully released, making it worth the effort. For example, in one of largest mass strandings in New Zealand in 2017, volunteers helped about 100 whales refloat, and made a human chain to try to stop them restranding.
Still, such events are likely to be more frequent in the future due to changing ocean conditions and increasing human activity such a noise pollution, commercial squid fisheries and deep sea mining.
We can help the whales not only by actively supporting rescue organisations such as ORRCA, but also by helping reduce carbon emissions, foster sustainable fisheries, reduce plastic pollution and advocate for marine sanctuaries.
Environmental scientists see flora, fauna and phenomena the rest of us rarely do. In this new series, we’ve invited them to share their unique photos from the field.
Tasmania’s native forests are home to some of the tallest, most beautiful trees in the world. They provide a habitat for many species, from black cockatoos and masked owls to the critically endangered swift parrot.
But these old, giant trees are being logged at alarming rates, despite their enormous ecological and heritage value (and untapped tourism potential). Many were also destroyed in Tasmania’s early 2019 fires.
Former Greens leader Bob Brown recently launched a legal challenge to Tasmania’s native forest logging. And this year, Forestry Watch, a small group of citizen scientists, found five giant trees measuring more than five metres in diameter inside logging coupes. “Coupes” are areas of forest chopped down in one logging operation.
These trees are too important to be destroyed in the name of the forestry industry. This is why my husband Steve Pearce and I climb, explore and photograph these trees: to raise awareness and foster appreciation for the forests and their magnificent giants.
Eualypytus regnans, known more commonly as Mountain Ash or Swamp Gum, can grow to 100 metres tall and live for more than 500 years. For a long time this species held the record as the tallest flowering tree. But last year, a 100.8 m tall Yellow Meranti (Shorea faguetiana) in Borneo, claimed the title — surpassing our tallest Eucalypt, named Centrioun, by a mere 30 centimetres.
Centrioun still holds the record as the tallest tree in the southern hemisphere. But five species of Eucalypt also grow above 85 m tall, with many ranking among some of the tallest trees in the world.
It’s not only their height that make these trees special, they’re also the most carbon dense forests in the world, with a single hectare storing more than 1,867 tonnes of carbon.
Our giant trees and old growth forests provide a myriad of ecological services such as water supply, climate abatement and habitat for threatened species. A 2017 study from the Central Highlands forests in Victoria has shown they’re worth A$310 million for water supply, A$260 million for tourism and A$49 million for carbon storage.
This significantly dwarfs the A$12 million comparison for native forest timber production in the region.
Logging organisation Sustainable Timber Tasmania’s giant tree policy recognises the national and international significance of giant trees. To qualify for protection, trees must be at least 85 m tall or at least an estimated 280 cubic metres in stem volume.
While it’s a good place to start, this policy fails to consider the next generation of big, or truly exceptional trees that don’t quite reach these lofty heights.
That’s why we’ve created Tasmania’s Big Tree Register, an open-source public record of the location and measurements of more than 200 trees to help adventurers and tree-admirers locate and experience these giants for themselves. And, we hope, to protect them.
Logging is a very poor economic use for our forests. Native forest logging in Tasmania has struggled to make a profit due to declining demand for non-Forest Stewardship Council certified timber, which Sustainable Timber Tasmania recently failed. In fact, Sustainable Timber Tasmania sustained an eye watering cash loss of A$454 million over 20 years from 1997 to 2017.
The following photos can help show why these trees, as one of the great wonders of the world, should be embraced as an important part of our environmental heritage, not turned to wood chips.
It’s not often you get to see the entirety of a tree in a single photo. This tree above is named Gandalf’s Staff and is a Eucalyptus regnans, measuring 84 m tall.
While Mountain Ash is the tallest species, others in Tasmania’s forests are also breathtakingly huge, such as the Tasmanian blue gum (Eucalyptus globulus) at 92 m, Manna gum (Eucalyptus viminalis) at 91 m, Alpine ash (Eucalyptus delegatensis) at 88 m and the Messmate Stringybark (Eucalyptus obliqua) at 86 m.
This giant tree, pictured above, was a Messmate Stringybark that was felled in coupe, but was left behind for unknown reasons. Its diameter is 4.4 metres. Other giant trees like this were cut down in this coupe, many of which provided excellent nesting habitat for the critically endangered swift parrot.
Old-growth forests dominated by giant trees are excellent at storing large amounts of carbon. Large trees continue to grow over their lifetime and absorb more carbon than younger trees.
The tree in the photo above is called Obolus, from Greek mythology, with a diameter of 5.1 m. Names are generally given to trees by the person who first records them, and usually reflect the characteristics of the tree or tie in with certain themes.
For example, several trees in a valley are all named after Lord of the Rings characters, such as Gandalf’s Staff (pictured above), Fangorn and Morannon.
Giant trees are typically associated with Californian Redwoods or the Giant Sequoias in the US, where tall tree tourism is huge industry. The estimated revenue in 2012 from just four Coastal Redwood reserves is A$58 million dollars per year, providing more than 500 jobs to the local communities.
Few Australians are aware of our own impressive trees. We could easily boost tourism to regional communities in Tasmania if the money was invested into tall tree infrastructure.
Until it was hunted to extinction, the thylacine – also known as the Tasmanian tiger or Tasmanian wolf – was the world’s largest marsupial predator. However, our new research shows it was in fact only about half as large as previously thought. So perhaps it wasn’t such a big bad wolf after all.
Although the thylacine is widely known as an example of human-caused extinction, there is a lot we still don’t know about this fascinating animal. This even includes one of the most basic details: how much did the thylacine weigh?
An animal’s body mass is one of the most fundamental aspects of its biology. It affects nearly every facet of its biology, from biochemical and metabolic processes, reproduction, growth, and development, through to where the animal can live and how it moves.
For meat-eating predators, body mass also determines what the animal eats – or more specifically, how much it has to eat at each meal.
Catching and eating other animals is hard work, so a predator has to weigh the costs carefully against the benefits. Small predators have low hunting costs – moving around, hunting, and killing small prey doesn’t cost much energy, so they can afford to nibble on small animals here and there. But for bigger predators, the stakes are higher.
Almost all large predators – those weighing at least 21 kilograms – focus their efforts on prey at least half their own body size, getting more bang for the buck. In contrast, small predators below 14.5 kg almost always catch prey much smaller than half their own size. Those in between typically take prey less than half their size, but sometimes switch to a larger meal if some easy prey is there for the taking – or if the predator is getting desperate.
Few accurately recorded weights exist for thylacines – only four, in fact. This lack of information has made estimating their average size difficult. The most commonly used average body mass is 29.5kg, based on 19th-century newspaper accounts.
This suggests the thylacine would probably have taken relatively large prey such as wallabies, kangaroos and perhaps sheep. However, studies of thylacine skulls suggest they didn’t have strong enough skulls to capture and kill large prey, and that they would have hunted smaller animals instead.
This presented a problem: if the thylacine was as big as we thought, it shouldn’t be able to live solely on small prey. But what if we’ve had the weight wrong the whole time?
Why did the Tasmanian tiger go extinct?
Our new research, published today in Proceedings of the Royal Society B, addresses this weighty issue. Our team travelled throughout the world to museums in Australia, the United States, the United Kingdom and Europe, and 3D-scanned 93 thylacines, including whole mounted skeletons, taxidermy mounts, and the only whole-body ethanol-preserved thylacine in the world, in Sweden.
Based on these scans, we created new equations to estimate a thylacine’s mass, based on how thick their limbs were – because their legs would have had to support their entire weight.
We also compared the results of these equations with a new method of digitally weighing 3D specimens. Based on a 3D scan of a mounted skeleton, we digitally “filled in the spaces” to estimate how much soft tissue would have been present, and then used our new formula to calculate how much this would weigh. Taxidermy mounts were easier as there was no need to infer the amount of soft tissue. The most artistic member of our team digitally sculpted lifelike thylacines around the scanned skeletons, and we weighed them, too.
Our calculations unanimously told a very different story from the 19th-century periodicals, and from the commonly used estimate. The average thylacine weighed only about 16.7 kg – not 29.5 kg.
This means the previous estimate, based on taking 19th-century periodicals at face value, was nearly 80% too large. Looking back at those old newspaper reports, many of them in retrospect have the hallmarks of “tall tales”, told to make a captured thylacine seem bigger, more impressive and more dangerous.
It was based on this suspected danger that the thylacine was hunted and trapped to extinction, with private bounties already placed on them by 1840, and government-sponsored extermination by the 1880s.
The thylacine was much smaller than previously thought, and this aligns with the smaller prey size suggested by the earlier studies. Predators below 21 kg – in which we should now include the thylacine – all tend to hunt prey smaller than half their size. The “Tasmanian wolf” probably wasn’t such a danger to Tasmanian farmers’ sheep after all.
By rewriting this fundamental aspect of their biology, we are closer to understanding the role of the thylacine in the ecosystem – and to seeing exactly what was lost when we deliberately hunted it to extinction.
Douglass Rovinsky, PhD Candidate, Monash University; Alistair Evans, Associate Professor, Monash University, and Justin W. Adams, Senior Lecturer, Department of Anatomy and Developmental Biology, Monash University
Moss bounds happily through the bush showing the usual exuberance of a young labrador. Despite this looking like play, he is on a serious mission to help fight the extinction of some of our most critically endangered species.
Moss is a detection dog in training. Unlike other detection dogs, who might sniff out drugs or explosives, he’ll be finding some of Victoria’s smallest, best camouflaged and most elusive animals.
These dogs use their exceptional olfactory senses to locate everything from koalas high in the trees, desert tortoises burrowed deep under soil and even whales — often more effectively than any human team could aspire to.
What makes Moss unique, however, is he’ll not only find endangered species in the wild, but will also be part of a larger team helping endangered species breed in captivity. These dogs will be the first in the world to do this, starting with a ground-breaking trial with Tasmanian devils.
And Moss is the first dog to join Zoos Victoria’s Detection Dog squad, a permanent group of highly trained dogs that will live at Healesville Sanctuary.
Moss was adopted at 14 months old, after he somewhat “failed” at being a family pet. He is a hurricane of energy with an intelligent and playful mind. He’s thriving with a job to keep him occupied and new challenges for his busy brain.
One sign he was perfect for this program was his indifference to the free range chickens at his foster home. For obvious reasons, a dog who likes chasing chickens wouldn’t be a good candidate for protecting some of Australia’s rarest feathered treasures.
Currently Moss is learning crucial foundational skills, and getting plenty of exposure to different environments. Equally important, he is developing a deep bond and trust with his handlers.
The detection dog-handler bond is crucial not only for his happiness, but also for working success and longevity. Research from 2018 found a strong bond between a handler and their dog dramatically improved the dog’s detection results and reduced signs of stress.
Healesville Sanctuary breeds endangered Tasmanian Devils every year as part of an insurance program to support conservation and research. This program is crucial to help protect the devil following an estimated 80% decline in the wild due to a horrific transmissible cancer, Devil Facial Tumour Disease.
But managing a predator that’s shy, nocturnal and prefers to be left alone can be tricky.
Wildlife, including Tasmanian devils, need a hands-off approach where possible, so they can maintain natural behaviours and thrive in their environment.
In the wild, devils leave scats (faeces) at communal latrine sites and use scent for communication. Male devils can tell a female is ready to mate by smelling her scat. And we think dogs could be trained to detect this, too.
We aim to train dogs to detect an odour profile in the collected scat of female devils coming into their receptive (oestrus) periods, so we can introduce females and suitable males to breed at the optimal time. The odour profile will be further verified via laboratory analyses of hormones in the scats.
The project will also explore whether dogs can detect pregnancy and lactation in the devils.
Currently, the best way to determine if a female has young is to look in her pouch, but our preference is to remain at a distance during this important time while females settle into being new mums.
If the dogs are able to smell a scat sample (while never coming into contact with the devil) and identify that a female is lactating with small joeys in her pouch, we can support her – for example, by increasing her food – while keeping a comfortable distance.
The results from this devil breeding research could offer innovative new options for endangered species breeding programs around the world.
Wildlife detection in the field means we can more accurately monitor some of our most critically endangered species, and quickly assess the impact of catastrophic events such as bushfires.
Detection dogs are the perfect intermediary between people and wildlife — they can sniff out what we can’t and communicate with us as a team.
And over the next few years, the Detection Dog Squad will expand to five full-time canines. They will all be selected based on their personalities rather than specific breeds, so will likely come in all shapes and sizes.
Dogs may yet go from being man’s best friend to the devil’s best friend and beyond, all starting with a happy labrador named Moss.
This article is co-authored by Naomi Hodgens, Wildlife Detection Dog Officer at Zoos Victoria, and Dr Kim Miller, Life Sciences Manager, Conservation and Research, at Healesville Sanctuary, Zoos Victoria.
La Toya Jamieson, Wildlife Detection Dog Specialist, La Trobe University and Marissa Parrott, Reproductive Biologist, Wildlife Conservation & Science, Zoos Victoria, and Honorary Research Associate, BioSciences, University of Melbourne
Emerging infectious diseases, including COVID-19, usually come from non-human animals. However our understanding of most animals’ immune systems is sadly lacking as there’s a shortfall in research tools for species other than humans and mice.
Our research published today in Science Advances details cutting edge immunology tools we developed to understand cancer in Tasmanian devils. Importantly, these tools can be rapidly modified for use on any animal species.
Our work will help future wildlife conservation efforts, as well as preparedness against potential new diseases in humans.
Tasmanian devil populations have undergone a steep decline in recent decades, due to a lethal cancer called devil facial tumour disease (DFTD) first detected in 1996.
A decade after it was discovered, genetic analysis revealed DFT cells are transmitted between devils, usually when they bite each other during mating. A second type of transmissible devil facial tumour (DFT2) was detected in 2014, suggesting devils are prone to developing contagious cancers.
In 2016, researchers reported some wild devils had natural immune responses against DFT1 cancers. A year later an experimental vaccine for the original devil facial tumour (DFT1) was tested in devils artificially inoculated with cancer cells.
While the vaccine didn’t protect them, in some cases subsequent treatments were able to induce tumour regression.
But despite the promising results, and other good news from the field, DFT1 continues to suppress devil populations across most of Tasmania. And DFT2 poses an additional threat.
In humans, there has been incredible progress in treatments targeting protein that regulate our immune system. These treatments work by stimulating the immune system to kill cancer cells.
Our team’s analyses of devil DNA showed these immune genes are also present in devils, meaning we may be able to develop similar treatments to stimulate the devil immune system.
But studying the DNA blueprint for devils takes us only so far. To build a strong house, you need to understand the blueprint and have the right tools. Proteins are the building blocks of life. So to build effective treatments and vaccines for devils we have to study the proteins in their immune system.
Until recently, there were few research tools available for this. And this problem was all too familiar to researchers studying immunology and disease in species other than humans, mice or rats.
You could build a house with just a saw, hammer and nails – but a better and faster build requires a larger, more versatile toolbox.
In our new research, we’ve added more than a dozen tools to the toolbox for understanding tumours in Tasmanian devils. These are Fluorescent Adaptable Simple Theranostic proteins – or simply, FAST proteins.
The term “theranostic” merges therapeutic and diagnostic. FAST proteins can be used as a therapeutic drug to treat a disease, or as a diagnostic tool to determine its cause and better understand it.
A key feature of FAST proteins is they can be tagged with a fluorescent protein marker, and can be released from the cells that we engineered in the lab to make them.
This way, we can collect and observe how the proteins attach and interact with other proteins without needing to add a tag later in the process.
To understand this, imagine trying to use a tiny key in a tiny lock in the dark. It would be difficult, but much easier if both were tagged with a coloured light. In the context of the immune system, it’s easier to understand what we need to turn on or off if we can see where the proteins are.
By mapping how proteins within the devil’s immune system interact, we can find better ways to stimulate the immune system.
The FAST system is also adaptable, meaning new targets can be cut-and-pasted into the system as they’re identified, like changing the bits on a drill. Therefore, it’s useful for studying the immune systems of other animals too, including humans.
Also, the system is simple enough that most people with basic cell culture and molecular biology experience could use it.
Cancer cells in humans and animals can travel via the bloodstream to spread, or “metastasise”, throughout the body. Identifying single tumour cells in blood can shed light on how cancer invades devils’ organs and kills them.
Using FAST tools, we discovered CD200 – a protein that inhibits anti-cancer responses in humans – is highly expressed in devils. With FAST tools, we were able to mix DFT2 cancer cells into devil blood and pick them out, despite there being about one cancer cell for every 1,000 blood cells.
CD200 is a powerful “off switch” for the immune system, so identifying this off switch allows us it can help us produce a vaccine that disables the switch.
By rapidly sifting out the best ways to stimulate the devil’s immune system, FAST tools are accelerating our research into developing a preventative vaccine to protect devils from DFT.
COVID-19 has once again brought emerging infectious diseases onto the global stage. The ability to rapidly develop immunology tools for new species means we can jump into action when a new virus jumps into humans.
Additionally, species are going extinct at an alarming rate, and wildlife disease is increasingly threatening conservation efforts.
Understanding how the immune systems of other animals fight diseases could provide a blueprint for developing vaccines and therapeutics to help them.
Andrew S. Flies, Senior Research Fellow in Immunology, University of Tasmania; Amanda L. Patchett, , University of Tasmania; Bruce Lyons, , University of Tasmania, and Greg Woods, Professional Research Fellow, University of Tasmania