The secret to bats' immunity

Date:  February 26, 2019

Source:  Duke-NUS Medical School

An international research team led by Duke-NUS Medical School, Singapore, has identified molecular and genetic mechanisms that allow bats to stay healthy while hosting viruses that kill other animals, according to a new study published in the journal Nature Microbiology.

Bats live very long and host numerous viruses, such as Ebola virus, Nipah virus, and severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) coronaviruses, that are extremely harmful when they infect humans and other animals. Researchers at Duke-NUS Medical School and colleagues wanted to find out how bats can harbour so many of these pathogens without suffering from diseases.

The key, they found, is in the bat's ability to limit inflammation. Bats do not react to infection with the typical inflammatory response that often leads to pathological damage. In humans, while the inflammatory response helps fight infection when properly controlled, it has also been shown to contribute to the damage caused by infectious diseases, as well as to aging and age-related diseases when it goes into overdrive.

The researchers found that the inflammation sensor that normally triggers the body's response to fight off stress and infection, a protein called NLRP3, barely reacts in bats compared to humans and mice, even in the presence of high viral loads.

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Poison pass: the man who became immune to snake venom

Rock singer Steve Ludwin has been injecting himself with snake venom for 30 years. In a strange twist, his bizarre habit could now save thousands of lives. His former partner Britt Collins tells his outlandish story

Britt Collins

Sun 11 Feb 2018 08.00 GMTLast modified on Mon 12 Feb 2018 11.16 GMT

Sometime in 2006, when my ex-boyfriend failed to show up for dinner, I assumed something was wrong or perhaps he’d forgotten. About a week later, calling to apologise, he told me he’d had an overdose, accidentally injecting a lethal cocktail of venom from three snakes. A lot has been written about Steve Ludwin, widely known as the man who injects snake venom, and lately his life has turned into a non-stop frenzy of international journalists and film crews revelling in the seeming sheer insanity of it.

Steve was once my great love; an animal lover, vegan and musician who wrote songs for Placebo and Ash, and played the Reading festival with Nirvana. In between tours and recordings he dabbled with snake venom. In his latest incarnation as a self-taught snake expert, moulding himself into the role of a lifetime, he appears as a kind of living specimen and star in a short film at the Natural History Museum’s new exhibition, Venom: Killer and Cure.

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Inssssane! Man CHOOSES to be bitten by venomous snakes

MEET the brave bloke who LETS poisonous snakes bite him and sink their venom into his body.

Tim Friede, 45, has survived over 100 bites from poisonous snakes after he built up his immunity by injecting himself with diluted venom.

Now he is only too happy to let a snake bite him on the arm and then sit back and let the pain subside.

Many would question why Tim, whose arm balloons in size due to the poison beringing about a potentially fatal allergic reaction, would want to do this, but he insists he has a good reason.

The jobless factory worker says he want to prove that millions of people who are at risk from snake bites could be made immune if they followed his lead.

He said: "I hope through developing my own resistance to poison some solid groundwork can be laid to build a vaccine for the 125,000 people who die from snakebites every year.

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UK bats may be immune to killer fungus

A deadly fungus thought responsible for killing nearly six million bats in North America since 2006 has been found in the UK with no harmful effects.

The fungus Pseudogymnoascus destructans has been discovered on a living bat and in soil samples from five sites.

There have been no observed deaths in the UK suggesting UK bats they may be resistant to the fungus

In the US it causes White-Nose Syndrome (WNS) and leads bats to arouse more frequently from hibernation.

The fungus has previously been found at sites across Europe, but without WNS or the associated large numbers of dead bats. It is likely European bats are also immune to the disease.

Bat Conservation Trust's Julia Hanmer said: "We believe that as with other countries in Europe, UK bats may be resistant to this fungus, because we're not seeing any signs of bats dying as a result of this fungus being present.

"Our understanding is that this fungus has been present in Europe for a very long time and that bats have grown a resistance to it. It's been introduced in North America where bats have not been exposed before and don't have resistance, that's why they're dying in large numbers."

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Our Microbes, Ourselves: Billions of Bacteria Within, Essential for Immune Function, Are Ours Alone

ScienceDaily (June 21, 2012) — Gut bacteria's key role in immunity is tuned to the host species, researchers have found, suggesting that the superabundant microbes lining our digestive tract evolved with us -- a tantalizing clue in the mysterious recent spike in human autoimmune disorders.

A new study reports that the superabundance of microbial life lining our GI tracts has coevolved with us. These internal bacteria, which are essential for a healthy immune system, are ultimately our evolutionary partners. In other words, humans may have co-evolved with gut bacteria unique to humans, which are not immunologically functional in other mammals.

This study, the first to demonstrate that microbes are specific to their host species, also sheds light on what's called 'the hygiene hypothesis.' According to this idea, living in increasingly hyper-hygienic environments might contribute to recent spikes in childhood allergies, as these beneficial host-specific microbes are hindered by the plethora of antibacterial home products and cleaning chemicals.


Read on:  http://www.sciencedaily.com/releases/2012/06/120621130643.htm

The downside of sex with Neanderthals (via Rob Chambers)

Some modern humans carry immune genes that originated in Neanderthals and a related species. But these genes may have come at a price
One question seemed to hang in the air more than any other when scientists first turned the powerful techniques of modern genetics on the fragile and damaged remains of ancient humans: did we or didn't we? Have sex with them, that is.

The answer came after years of painstaking work, when material extracted from the leg of a Neanderthal and the fingerbone of a Denisovan, an apparent sister species, yielded readable DNA. It turned out that most of us have some of their genes. The Neanderthals contributed up to 4% of modern Eurasian genomes, while the Denisovans contributed roughly 4-6% of modern Melanesian genomes. That doesn't happen by holding hands.

And so the scene was set. Hundreds of thousands of years ago, early humans in Africa split into several groups, among them Homo sapiens, Neanderthals and their apparent sister species, the Denisovans. The Neanderthals headed for West Asia and Europe, the Denisovans to East Asia. Our ancestors left Africa much later, and arrived in Eurasia where the others had set up home. Cue amorous encounters, and surely a fair amount of less than amorous contact.

But the question of whether our ancestors mated with these other human-like groups was always just the starting point for a line of inquiry. With interbreeding now well-established the intriguing question is, what came of it? How did our ancestors' antics shape the people we are today?

A glimpse of the legacy of those ancient encounters is revealed in a study reported today in the US journal, Science. An international team of scientists, led by Stanford University, scoured the Neanderthal and Denisovan genomes for gene variants that are central to the immune system. These genes belong to a group known as the HLA class I genes, which govern the body's ability to recognise and destroy dangerous pathogens.

By comparing the HLA genes of modern human populations with those from Denisovans and Neanderthals, the scientists identified a handful that could be traced back to ancient sexual encounters between the groups. One variant, known as HLA-B*73, likely arose in modern humans after cross-breeding with Denisovans. The variant is most common in West Asian populations, the region where the mating probably happened.

The Neanderthals contributed a string of HLA gene variants, or alleles, to the modern Eurasian population's gene pool, the study found.

There was good reason for Neanderthal and Denisovan immune system genes to have spread through the populations of modern humans who encountered them. Both Neanderthals and Denisovans had established themselves long before modern humans arrived. Their immune systems had adapted to the threats of the local environment. When those genes crossed into modern humans, they conveyed an advantage. Natural selection took care of the rest.

But the scientists think there was a downside. Inheriting Denisovan or Neanderthal immunity genes will have helped modern humans to fight the diseases of the day, but beyond the age of reproductive maturity they might have a more harmful effect, turning our immune systems on ourselves.

Paul Norman, a co-author on the paper, put it like this: "There's enormous genetic variation in people's immune systems and that can control how different people fight different diseases. This could go some way to explaining why some people are better at fighting some infections than others, but we think it also goes some way to explaining why some people are susceptible to autoimmune diseases."

Autoimmune diseases are conditions that arise when the immune system turns its firepower on the body, usually when it mistakenly identifies the body's tissues as foreign, and so potentially dangerous.

"The vast majority of autoimmune diseases have been shown by genome-wide association studies to be associated with particular HLA alleles and we find a couple of those in Denisovans," Norman added. "So it looks to me like modern humans have acquired these alleles, but we weren't kind of prepared for them, we hadn't grown up with them, and in some circumstances, they can start to attack us as well as the viruses and other pathogens."

The group is now investigating a gene variant called HLA-B51, which came from cross-breeding with Neanderthals and has already been linked to Behcet's disease, a rare and chronic inflammatory condition.

How else might immune genes inherited from Neanderthals and Denisovans affect the health of modern humans? The question is intriguing and will differ from population to population. Here, at least, is a worthy successor to the question of "did we or didn't we?"
http://www.guardian.co.uk/science/blog/2011/aug/25/neanderthal-denisovan-genes-human-immunity>