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Scientists find new details about how immune system builds long-term memory

Experts in Japan have identified a fundamental part of the immune system’s long-term memory, providing a useful new detail in the pursuit to design better vaccines for diseases, ranging from COVID-19 to malaria. The research, published in the Journal…

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Experts in Japan have identified a fundamental part of the immune system’s long-term memory, providing a useful new detail in the pursuit to design better vaccines for diseases, ranging from COVID-19 to malaria. The research, published in the Journal of Experimental Medicine, reveals a new role for the enzyme TBK1 in deciding the fate of immune system memory B cells.

Credit: Image by Michelle S.J. Lee, Creative Commons By Attribution No Derivatives
https://creativecommons.org/licenses/by-nd/4.0/

Experts in Japan have identified a fundamental part of the immune system’s long-term memory, providing a useful new detail in the pursuit to design better vaccines for diseases, ranging from COVID-19 to malaria. The research, published in the Journal of Experimental Medicine, reveals a new role for the enzyme TBK1 in deciding the fate of immune system memory B cells.

The immune system is made of many cell types, but the two types relevant for this University of Tokyo research project are white blood cells called CD4+ follicular helper T cells and B cells. After the body recognizes an infection, the follicular helper T cells release chemical signals that cause immature B cells to learn and remember what pathogens to attack. This process of T-to-B cell signaling and B cell training occurs within a temporary cell structure called the germinal center in organs of the immune system, including the spleen, lymph nodes and tonsils. Memory B cells developed within the germinal center memorize a pathogen the first time it infects you and then if it ever gets into your body again, the mature, trained memory B cells attack it by inducing antibody production before the pathogen can multiply, saving you from feeling sick a second time. 

“A goal of vaccination is to produce high-quality memory B cells for long-lasting antibody production,” said Project Assistant Professor Michelle S. J. Lee from the UTokyo Institute of Medical Science, first author of the recent publication.

“There are many factors to consider when designing vaccines for long-lasting immunity, so we should not focus only on the germinal center alone. But if you don’t have a functional germinal center, then you will be very susceptible to reinfection,” said Lee.

However, there is no limit to the number of times you can be bitten by mosquitoes and reinfected by the malaria parasite. Somehow, malaria parasites escape memory B cells. Although children are more likely to die from malaria than adults, some people can become severely ill despite any number of previous malaria infections.

This ability of the parasite to prevent and evade effective B cells is what makes malaria an interesting pathogen for Professor Cevayir Coban, who leads the Division of Malaria Immunology at the UTokyo Institute of Medical Science and is last author of the research paper with Lee and collaborators at Osaka University.

“We want to understand the fundamentals of the natural immune response. Whatever we do should aim to eventually benefit malaria patients,” said Coban. “The COVID-19 pandemic brought global attention to infectious diseases and interest in vaccine design, so we have a chance to renew the focus on neglected diseases like malaria,” she continued.

Over many years, the scientific community has identified a wide range of roles for the molecule TBK1, an enzyme that can alter the activity of genes or other proteins by adding chemical tags, through a process called phosphorylation. TBK1 has well-known roles in antiviral immunity. However, no research group had connected TBK1 to B cell fate and the germinal center.

Researchers genetically modified mice that had nonfunctional TBK1 genes only in specific types of cells, primarily either B cells or CD4+ T cells. This cell type-specific knockout of TBK1 gives researchers a clearer idea of what a gene with many jobs is doing in different cells of the body. Coban, Lee and their colleagues infected these modified mice and healthy adult mice with the malaria parasite, observed their health, and then examined samples of their spleens and lymph nodes.

Microscopy images revealed that germinal centers only form in mice that have functional TBK1 in their B cells. Mice with no TBK1 in their B cells were more likely to die and died sooner from the malaria infection than their normal peers. Additional experiments showed that the few mice who survived malaria with no TBK1 in their B cells were able to use other types of immune responses, but they can become reinfected.

However, deleting TBK1 only from the CD4+ follicular helper T cells had no effect on the germinal centers or how the mice fared with a malaria infection.

Further analysis confirmed that without TBK1, many proteins in immature B cells had abnormal phosphorylation compared to normal immature B cells. For different genes, abnormal phosphorylation can cause either abnormal increases or decreases in activity. Researchers suspect that in B cells, TBK1 activity acts as an off switch for certain genes, essentially turning off genes that trap the B cells in their immature state.

“This is the first time to show TBK1 is essential in B cells to form the germinal centers and produce high-quality, mature antibodies,” said Lee.

Researchers are hopeful that eventually, with more fundamental knowledge about the remaining mysteries of the immune system, future vaccines can be designed to produce longer-lasting immunity, potentially without needing multiple doses of vaccine. However, vaccine design will always be complicated by the unique qualities of each pathogen and its mutated versions, especially in the case of rapidly evolving pathogens like Sars-CoV-2, the virus causing COVID-19.

“For now, we can at least say that an effective vaccine tailored to produce long-lasting protective immunity should not reduce TBK1 activity in B cells,” said Coban.

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Research Publication

Michelle S. J. Lee, Takeshi Inoue, Wataru Ise, Julia Matsuo-Dapaah, James B. Wing, Burcu Temizoz, Kouji Kobiyama, Tomoya Hayashi, Ashwini Patil, Shimon Sakaguchi, A. Katharina Simon, Jelena S. Bezbradica, Satoru Nagatoishi, Kouhei Tsumoto, Jun-Ichiro Inoue, Shizuo Akira, Tomohiro Kurosaki, Ken J. Ishii, Cevayir Coban. December 2021. B cell intrinsic TBK1 is essential for germinal center formation during infection and vaccination in mice. Journal of Experimental Medicine. DOI: 10.1084/jem.20211336.

Related Links

Institute of Medical Science Division of Malaria Immunology (Coban Lab):  https://www.ims.u-tokyo.ac.jp/malimmun/
Institute of Medical Science: https://www.ims.u-tokyo.ac.jp/imsut/en/index.html

Research Contact

Professor Cevayir Coban
E-mail: ccoban[at]ims.u-tokyo.ac.jp
Tel: +81-03-6409-2220

Press Officer Contact

Ms. Caitlin Devor
Division for Strategic Public Relations, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 133-8654, JAPAN
Email: press-releases.adm@gs.mail.u-tokyo.ac.jp

About the University of Tokyo

The University of Tokyo is Japan’s leading university and one of the world’s top research universities. The vast research output of some 6,000 researchers is published in the world’s top journals across the arts and sciences. Our vibrant student body of around 15,000 undergraduate and 15,000 graduate students includes over 4,000 international students. Find out more at http://www.u-tokyo.ac.jp/en/ or follow us on Twitter at @UTokyo_News_en.

Funders

Japan Science and Technology Agency
Ministry of Education, Culture, Sports, Science and Technology of Japan
Japan Agency for Medical Research and Development


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The next pandemic? It’s already here for Earth’s wildlife

Bird flu is decimating species already threatened by climate change and habitat loss.

I am a conservation biologist who studies emerging infectious diseases. When people ask me what I think the next pandemic will be I often say that we are in the midst of one – it’s just afflicting a great many species more than ours.

I am referring to the highly pathogenic strain of avian influenza H5N1 (HPAI H5N1), otherwise known as bird flu, which has killed millions of birds and unknown numbers of mammals, particularly during the past three years.

This is the strain that emerged in domestic geese in China in 1997 and quickly jumped to humans in south-east Asia with a mortality rate of around 40-50%. My research group encountered the virus when it killed a mammal, an endangered Owston’s palm civet, in a captive breeding programme in Cuc Phuong National Park Vietnam in 2005.

How these animals caught bird flu was never confirmed. Their diet is mainly earthworms, so they had not been infected by eating diseased poultry like many captive tigers in the region.

This discovery prompted us to collate all confirmed reports of fatal infection with bird flu to assess just how broad a threat to wildlife this virus might pose.

This is how a newly discovered virus in Chinese poultry came to threaten so much of the world’s biodiversity.

H5N1 originated on a Chinese poultry farm in 1997. ChameleonsEye/Shutterstock

The first signs

Until December 2005, most confirmed infections had been found in a few zoos and rescue centres in Thailand and Cambodia. Our analysis in 2006 showed that nearly half (48%) of all the different groups of birds (known to taxonomists as “orders”) contained a species in which a fatal infection of bird flu had been reported. These 13 orders comprised 84% of all bird species.

We reasoned 20 years ago that the strains of H5N1 circulating were probably highly pathogenic to all bird orders. We also showed that the list of confirmed infected species included those that were globally threatened and that important habitats, such as Vietnam’s Mekong delta, lay close to reported poultry outbreaks.

Mammals known to be susceptible to bird flu during the early 2000s included primates, rodents, pigs and rabbits. Large carnivores such as Bengal tigers and clouded leopards were reported to have been killed, as well as domestic cats.

Our 2006 paper showed the ease with which this virus crossed species barriers and suggested it might one day produce a pandemic-scale threat to global biodiversity.

Unfortunately, our warnings were correct.

A roving sickness

Two decades on, bird flu is killing species from the high Arctic to mainland Antarctica.

In the past couple of years, bird flu has spread rapidly across Europe and infiltrated North and South America, killing millions of poultry and a variety of bird and mammal species. A recent paper found that 26 countries have reported at least 48 mammal species that have died from the virus since 2020, when the latest increase in reported infections started.

Not even the ocean is safe. Since 2020, 13 species of aquatic mammal have succumbed, including American sea lions, porpoises and dolphins, often dying in their thousands in South America. A wide range of scavenging and predatory mammals that live on land are now also confirmed to be susceptible, including mountain lions, lynx, brown, black and polar bears.

The UK alone has lost over 75% of its great skuas and seen a 25% decline in northern gannets. Recent declines in sandwich terns (35%) and common terns (42%) were also largely driven by the virus.

Scientists haven’t managed to completely sequence the virus in all affected species. Research and continuous surveillance could tell us how adaptable it ultimately becomes, and whether it can jump to even more species. We know it can already infect humans – one or more genetic mutations may make it more infectious.

At the crossroads

Between January 1 2003 and December 21 2023, 882 cases of human infection with the H5N1 virus were reported from 23 countries, of which 461 (52%) were fatal.

Of these fatal cases, more than half were in Vietnam, China, Cambodia and Laos. Poultry-to-human infections were first recorded in Cambodia in December 2003. Intermittent cases were reported until 2014, followed by a gap until 2023, yielding 41 deaths from 64 cases. The subtype of H5N1 virus responsible has been detected in poultry in Cambodia since 2014. In the early 2000s, the H5N1 virus circulating had a high human mortality rate, so it is worrying that we are now starting to see people dying after contact with poultry again.

It’s not just H5 subtypes of bird flu that concern humans. The H10N1 virus was originally isolated from wild birds in South Korea, but has also been reported in samples from China and Mongolia.

Recent research found that these particular virus subtypes may be able to jump to humans after they were found to be pathogenic in laboratory mice and ferrets. The first person who was confirmed to be infected with H10N5 died in China on January 27 2024, but this patient was also suffering from seasonal flu (H3N2). They had been exposed to live poultry which also tested positive for H10N5.

Species already threatened with extinction are among those which have died due to bird flu in the past three years. The first deaths from the virus in mainland Antarctica have just been confirmed in skuas, highlighting a looming threat to penguin colonies whose eggs and chicks skuas prey on. Humboldt penguins have already been killed by the virus in Chile.

A colony of king penguins.
Remote penguin colonies are already threatened by climate change. AndreAnita/Shutterstock

How can we stem this tsunami of H5N1 and other avian influenzas? Completely overhaul poultry production on a global scale. Make farms self-sufficient in rearing eggs and chicks instead of exporting them internationally. The trend towards megafarms containing over a million birds must be stopped in its tracks.

To prevent the worst outcomes for this virus, we must revisit its primary source: the incubator of intensive poultry farms.

Diana Bell does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

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This is the biggest money mistake you’re making during travel

A retail expert talks of some common money mistakes travelers make on their trips.

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Travel is expensive. Despite the explosion of travel demand in the two years since the world opened up from the pandemic, survey after survey shows that financial reasons are the biggest factor keeping some from taking their desired trips.

Airfare, accommodation as well as food and entertainment during the trip have all outpaced inflation over the last four years.

Related: This is why we're still spending an insane amount of money on travel

But while there are multiple tricks and “travel hacks” for finding cheaper plane tickets and accommodation, the biggest financial mistake that leads to blown travel budgets is much smaller and more insidious.

A traveler watches a plane takeoff at an airport gate.

Jeshoots on Unsplash

This is what you should (and shouldn’t) spend your money on while abroad

“When it comes to traveling, it's hard to resist buying items so you can have a piece of that memory at home,” Kristen Gall, a retail expert who heads the financial planning section at points-back platform Rakuten, told Travel + Leisure in an interview. “However, it's important to remember that you don't need every souvenir that catches your eye.”

More Travel:

According to Gall, souvenirs not only have a tendency to add up in price but also weight which can in turn require one to pay for extra weight or even another suitcase at the airport — over the last two months, airlines like Delta  (DAL) , American Airlines  (AAL)  and JetBlue Airways  (JBLU)  have all followed each other in increasing baggage prices to in some cases as much as $60 for a first bag and $100 for a second one.

While such extras may not seem like a lot compared to the thousands one might have spent on the hotel and ticket, they all have what is sometimes known as a “coffee” or “takeout effect” in which small expenses can lead one to overspend by a large amount.

‘Save up for one special thing rather than a bunch of trinkets…’

“When traveling abroad, I recommend only purchasing items that you can't get back at home, or that are small enough to not impact your luggage weight,” Gall said. “If you’re set on bringing home a souvenir, save up for one special thing, rather than wasting your money on a bunch of trinkets you may not think twice about once you return home.”

Along with the immediate costs, there is also the risk of purchasing things that go to waste when returning home from an international vacation. Alcohol is subject to airlines’ liquid rules while certain types of foods, particularly meat and other animal products, can be confiscated by customs. 

While one incident of losing an expensive bottle of liquor or cheese brought back from a country like France will often make travelers forever careful, those who travel internationally less frequently will often be unaware of specific rules and be forced to part with something they spent money on at the airport.

“It's important to keep in mind that you're going to have to travel back with everything you purchased,” Gall continued. “[…] Be careful when buying food or wine, as it may not make it through customs. Foods like chocolate are typically fine, but items like meat and produce are likely prohibited to come back into the country.

Related: Veteran fund manager picks favorite stocks for 2024

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As the pandemic turns four, here’s what we need to do for a healthier future

On the fourth anniversary of the pandemic, a public health researcher offers four principles for a healthier future.

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John Gomez/Shutterstock

Anniversaries are usually festive occasions, marked by celebration and joy. But there’ll be no popping of corks for this one.

March 11 2024 marks four years since the World Health Organization (WHO) declared COVID-19 a pandemic.

Although no longer officially a public health emergency of international concern, the pandemic is still with us, and the virus is still causing serious harm.

Here are three priorities – three Cs – for a healthier future.

Clear guidance

Over the past four years, one of the biggest challenges people faced when trying to follow COVID rules was understanding them.

From a behavioural science perspective, one of the major themes of the last four years has been whether guidance was clear enough or whether people were receiving too many different and confusing messages – something colleagues and I called “alert fatigue”.

With colleagues, I conducted an evidence review of communication during COVID and found that the lack of clarity, as well as a lack of trust in those setting rules, were key barriers to adherence to measures like social distancing.

In future, whether it’s another COVID wave, or another virus or public health emergency, clear communication by trustworthy messengers is going to be key.

Combat complacency

As Maria van Kerkove, COVID technical lead for WHO, puts it there is no acceptable level of death from COVID. COVID complacency is setting in as we have moved out of the emergency phase of the pandemic. But is still much work to be done.

First, we still need to understand this virus better. Four years is not a long time to understand the longer-term effects of COVID. For example, evidence on how the virus affects the brain and cognitive functioning is in its infancy.

The extent, severity and possible treatment of long COVID is another priority that must not be forgotten – not least because it is still causing a lot of long-term sickness and absence.

Culture change

During the pandemic’s first few years, there was a question over how many of our new habits, from elbow bumping (remember that?) to remote working, were here to stay.

Turns out old habits die hard – and in most cases that’s not a bad thing – after all handshaking and hugging can be good for our health.

But there is some pandemic behaviour we could have kept, under certain conditions. I’m pretty sure most people don’t wear masks when they have respiratory symptoms, even though some health authorities, such as the NHS, recommend it.

Masks could still be thought of like umbrellas: we keep one handy for when we need it, for example, when visiting vulnerable people, especially during times when there’s a spike in COVID.

If masks hadn’t been so politicised as a symbol of conformity and oppression so early in the pandemic, then we might arguably have seen people in more countries adopting the behaviour in parts of east Asia, where people continue to wear masks or face coverings when they are sick to avoid spreading it to others.

Although the pandemic led to the growth of remote or hybrid working, presenteeism – going to work when sick – is still a major issue.

Encouraging parents to send children to school when they are unwell is unlikely to help public health, or attendance for that matter. For instance, although one child might recover quickly from a given virus, other children who might catch it from them might be ill for days.

Similarly, a culture of presenteeism that pressures workers to come in when ill is likely to backfire later on, helping infectious disease spread in workplaces.

At the most fundamental level, we need to do more to create a culture of equality. Some groups, especially the most economically deprived, fared much worse than others during the pandemic. Health inequalities have widened as a result. With ongoing pandemic impacts, for example, long COVID rates, also disproportionately affecting those from disadvantaged groups, health inequalities are likely to persist without significant action to address them.

Vaccine inequity is still a problem globally. At a national level, in some wealthier countries like the UK, those from more deprived backgrounds are going to be less able to afford private vaccines.

We may be out of the emergency phase of COVID, but the pandemic is not yet over. As we reflect on the past four years, working to provide clearer public health communication, avoiding COVID complacency and reducing health inequalities are all things that can help prepare for any future waves or, indeed, pandemics.

Simon Nicholas Williams has received funding from Senedd Cymru, Public Health Wales and the Wales Covid Evidence Centre for research on COVID-19, and has consulted for the World Health Organization. However, this article reflects the views of the author only, in his academic capacity at Swansea University, and no funding or organizational bodies were involved in the writing or content of this article.

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