Milestones in Europe: First results in using new tools to tackle respiratory syncytial virus

Protecting infants from respiratory syncytial virus (RSV) with new tools: vaccines for pregnant women and use of monoclonal antibodies have been approved for use in the European Union to prevent RSV among young children. Are those tools working?

Peer-Reviewed Publication

EUROPEAN CENTRE FOR DISEASE PREVENTION AND CONTROL (ECDC)

 

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PHYLOGENETIC TREE OF RESPIRATORY SYNCYTIAL VIRUS G AND F SEQUENCES PUBLISHED IN GISAID (N = 2,314 RSV A; N = 2,875 RSV B)

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CREDIT: EUROSURVEILLANCE

Each year, an estimated 101,000 children below the age of 5 years die across the globe due to infections caused by respiratory syncytial virus (RSV). Worldwide, RSV is a main cause of hospitalisation among young children. [1]

It took more than 60 years to develop and approve vaccines against RSV that can now be used to immunise both elderly people and pregnant women in the European Union (EU). In addition, a long-acting monoclonal antibody (nirsevimab) was licensed in the EU for use in infants end of 2022. Both events marked a milestone in the attempt to prevent RSV infections especially in very young children.

In an editorial in Eurosurveillance, Eeva Broberg and Hanna Nohynek [2] look at these recent advances and which supporting measures might be needed to understand the actual burden of RSV, its annual circulation patterns and genomic evolution.

For that understanding to improve, Broberg and Nohynek argue that “sequencing data need to be collected and reported to publicly accessible databases. As for other respiratory viruses and most infectious diseases, under-ascertainment will remain an issue for RSV surveillance in general as patients may present late for testing after the infection or not even be tested if they present with mild symptoms.”

Overcoming the challenges of sequencing RSV
To illustrate the current changes in tackling RSV infections across Europe, Broberg and Nohynek relate to the rapid communication in the same Eurosurveillance issue. Iglesias-Caballero et al. describe two PCR-based sequencing systems for RSV that can be used as methods to monitor the genetic diversity of the virus and with that inform molecular epidemiology, vaccine effectiveness and treatment strategies.

The authors show that their approach is less labour-intensive and less costly and presents the opportunity to increase laboratory capacities and probably also shorten throughput times. According to Broberg and Nohynek, the study from Spain demonstrates that the method outlined by Iglesias-Caballero et al. “can be used in retrospective molecular epidemiological studies of RSV and even with the simplified approach to sequence only the G and F gene genome, molecular evolution of RSV could be assessed.”

Complementing this RSV article from Spain, Martinón-Torres et al. [3] review first experiences in the autonomous community Galicia (northern Spain) following the implementation of universal RSV prophylaxis in infants with long-acting monoclonal antibodies. Both Spain and France have already introduced nirsevimab in their national immunisation programmes.

Based on the findings in Galicia, the early uptake of nirsevimab, which had a range of 81–98% in this region according to the study, has exceeded expectations. This immunisation achievement is the result of successful targeting and rationally designed immunisation logistics. According to the authors, the implementation and motivation of parents to immunise their children was likely facilitated by the quite intense RSV epidemic in Europe during the autumn 2022 in combination with awareness raising campaigns.

As Broberg and Nohynek put it, “the value of the work of Martinón-Torres et al. lies not only in the clear and meticulous description of how implementation challenges were approached, i.e. by distinguishing infants belonging to the seasonal and catch-up or high-risk groups, which provides an excellent example to other European countries, but also in the fact that Galicia will be able to answer the burning question on whether universal introduction of nirsevimab in the real- world setting is a cost-effective intervention on the short as well as the long run. If preventing RSV infection in early life can reduce asthma later in life, the impact of the intervention will be manifold.”

The European Centre for Disease Prevention and Control and the World Health Organization Regional Office for Europe have agreed on an integrated respiratory surveillance, which also includes RSV, and the weekly results are published in the European Respiratory Virus Surveillance Summary

 

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References/notes to editors:
[1] Li Y, Wang X, Blau DM, Caballero MT, Feikin DR, Gill CJ, et al. Global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in children younger than 5 years in 2019: a systematic analysis. Lancet. 2022;399(10340):2047-64.  https://doi.org/10.1016/S0140-6736(22)00478-0  PMID: 35598608

[2] Broberg Eeva K, Nohynek Hanna. Respiratory syncytial virus infections – recent developments providing promising new tools for disease prevention. Euro Surveill. 2023;28(49):pii=2300686. https://doi.org/10.2807/1560-7917.ES.2023.28.49.2300686

[3] Martinón-Torres Federico, Mirás-Carballal Susana, Durán-Parrondo Carmen. Early lessons from the implementation of universal respiratory syncytial virus prophylaxis in infants with long-acting monoclonal antibodies, Galicia, Spain, September and October 2023. Euro Surveill. 2023;28(49):pii=2300606. https://doi.org/10.2807/1560-7917.ES.2023.28.49.2300606

[4] Respiratory syncytial virus (RSV) is a common respiratory virus that causes mild, cold-like symptoms. People who contract RSV usually recover in around a week without the need for medical treatment. However, in infants under six months of age, people over 65, and people with a compromised immune system, RSV can cause severe illness and death. Symptoms usually appear two to eight days after being infected. Read more: https://www.ecdc.europa.eu/en/respiratory-syncytial-virus-rsv

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JOURNAL

Eurosurveillance

DOI

10.2807/1560-7917.ES.2023.28.49.2300606 

METHOD OF RESEARCH

Commentary/editorial

ARTICLE TITLE

Respiratory syncytial virus infections – recent developments providing promising new tools for disease prevention

ARTICLE PUBLICATION DATE

7-Dec-2023

COI STATEMENT

Hanna Nohynek: Co-lead of Work package 2 of the Innovate Health Initiative’s Preparing for RSV Immunisation and Surveillance in Europe (PROMISE) project (https://imi-promise.eu), member of the National Immunization Technical Advisory Group of the Finnish Institute for Health and Welfare, and chair of the Strategic Advisory Group of Experts of the World Health Organization.

 

40 years after the discovery of HIV, research raises hopes of remission

Meeting Announcement

INSTITUT PASTEUR

 

IMAGE: 

ONE OF THE VERY FIRST PHOTOGRAPHS OF THE HIV-1 VIRUS (COLORIZED BLUE) TAKEN ON FEBRUARY 4, 1983.

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CREDIT: © INSTITUT PASTEUR/CHARLES DAUGUET

Nearly 39 million people worldwide are carriers of human immunodeficiency virus (HIV), and 1.3 million people contracted HIV in 2022[1]. Forty years after the virus was discovered at the Institut Pasteur, HIV research is still active – the aim is to elucidate the mechanisms of infection so that the virus can be eradicated. A concerted global effort has led to considerable progress in knowledge. The conference "40 years of HIV science," which took place from November 29 to December 1 at the Institut Pasteur in collaboration with ANRS | Emerging Infectious Diseases, was an opportunity to look back at the major advances that are now raising hopes of remission and a cure for HIV.

For the past 40 years, since HIV was identified at the Institut Pasteur, scientists have been working to describe the virus and to understand the different stages from initial infection to integration in the host cell genome. This knowledge has led to considerable scientific and medical progress to slow infection, and has also improved the life expectancy and quality of life of people living with HIV. The participants in the opening session of the conference "40 years of HIV science" share the observation that although there have been major breakthroughs, the battle against HIV is not over, even if they have high hopes of finding avenues for remission and a cure: "I salute all these years of research, medical progress and activism, but there are still many challenges to overcome. Despite all the progress made, 630,000 people died from AIDS in 20221 and new infections continue to occur. The fight against HIV is not over. This international battle continues, and no one will be left behind!" said Stewart Cole, President of the Institut Pasteur.

Forty years after the discovery of HIV, basic research continues to shed light on mechanisms of infection

In response to these challenges, several different fields of investigation are being actively explored, especially to elucidate the molecular mechanisms that underpin HIV replication and viral integration into the host cell genome. State-of-the-art techniques have led to the surprising discovery that the virus targets the cell nucleus. It exploits host cell mechanisms to multiply its genome and produce viral particles that infect other cells. This discovery that HIV targets the cell nucleus opens new avenues for tackling viral replication and persistence. Another approach under exploration is innate immunity, in other words the body's defenses, which can be harnessed to block the virus as soon as it enters the cell. It may be possible to stimulate this natural response by developing immunotherapy treatments.

Removing the virus from all the cells in the body where it is present is crucial to avoid viral persistence. Scientists are using new technologies to understand how the virus evades the immune system and antiretroviral treatments to remain in reservoirs, and to determine the location of these viral reservoirs. Lymph nodes and intestines are among the reservoirs that scientists are investigating closely.

Analyzing the natural ability of some individuals to suppress the virus

How is it that some people are able to suppress HIV without antiretroviral treatment, by slowing its progression or preventing the reactivation of viral reservoirs? These people are able to control HIV infection because of an optimal immune response that neutralizes the virus. One strategy that is being explored as a novel therapeutic solution to overcome HIV infection is to attempt to reproduce the particularities of the immune cells responsible for this optimal response.

"The identification of HIV control in some individuals has significantly boosted hopes of remission and cure and has given us a unique opportunity to study the underlying mechanisms," explains Asier Sáez-Cirión, Head of the Institut Pasteur's Viral Reservoirs and Immune Control Unit.

Scientists are also interested in people who, despite repeated exposure to HIV, have never been infected because they have a genetic mutation that stops the virus from entering their cells. This mutation could be induced by gene therapy. Developing molecular scissors to make the body resistant or targeting the virus to eliminate it after its integration in the cell are fields of study that might pave the way to a long-term cure.

Using social sciences to make sure therapeutic innovation is accessible to everyone

As well as the challenges in medical research to improve our understanding of the mechanism of action of HIV infection, there are also societal challenges. Patient organizations, scientists and researchers in social sciences have been working together for the past 40 years to change attitudes to HIV and AIDS by tackling discrimination and the stigma attached to people living with HIV and by calling on authorities to help improve prevention and early diagnosis. The availability of rapid diagnostic tests is one of the tangible results of this collective effort. Therapeutic innovation alone is not enough – it needs to go hand in hand with targeted, relevant programs that will reach people at risk of HIV infection. The aim of the community-based research that has developed as part of the fight against HIV is to complement existing knowledge to reduce inequalities in access and to tailor strategies to patients' real-life circumstances. 9.2 million people living with HIV still did not have access to antiretroviral treatment in 2022. Access to antiretroviral treatment and infection prevention methods like PrEP (pre-exposure prophylaxis) is also a social battle that is being fought by stakeholders in the war against HIV.

To achieve the goal of eradicating HIV, the members of the international community that attended the conference confirmed that we need to double down on our efforts to explore all the scientific avenues that are opened with each new discovery related to the virus, and to step up work on prevention and access to therapies.

Finally, it is worth noting that the expertise that has developed in the field of HIV research over the past 40 years has also helped us tackle other diseases, including the recent COVID pandemic.

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[1] UNAIDS

Engaging heterosexual men more effectively could slash HIV infections in Uganda

Peer-Reviewed Publication

IMPERIAL COLLEGE LONDON

 

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COMMUNITY LEADERS IN SOUTHERN UGANDA AND RAKAI HEALTH SCIENCES PROGRAM RESEARCH STAFF PARTICIPATE IN A COMMUNITY FOOTBALL TOURNAMENT TO RAISE AWARENESS FOR HIV

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CREDIT: RAKAI HEALTH SCIENCES PROGRAM

A study looking at 15 years of HIV transmission and suppression in Uganda reveals how closing gender gaps in treatment could slash infection rates.

Providing more heterosexual men with easy access to HIV treatment and care could help to suppress the virus and rapidly cut transmission to their female partners, shows a new study published in Nature Microbiology.

The research, led by scientists from Imperial College London and the Rakai Health Sciences Program in Uganda, analysed 15 years of data from 2003-2018, during which the US President’s Emergency Plan For AIDS Relief (PEPFAR) has delivered an extensive programme of HIV/AIDS testing, prevention, and treatment.

This included distributing Antiretroviral Therapy (ART) drugs, which supress the virus so a person is no longer infectious. The analysis shows that the PEPFAR program and other services have greatly reduced new infections among young women and heterosexual men, but that reductions were less substantial in women aged 25 and above.

This is thought to be because women are more likely to reach viral suppression through uptake and effective use of HIV treatment, preventing them from passing HIV to their male partners, but that the same is not true the other way around.

Gender disparity

The analysis showed that the number of women reaching and maintaining undetectable (non-transmissible) levels of HIV infection were 1.5 to 2 times higher than men across all ages by the year 2018. The analysis shows that had men reached the same levels of virus suppression as women, around half the new infections that occurred between 2016 and 2018 could have been avoided.

The team also reconstructed transmission networks based on the genetic code of the virus from thousands of participants, which confirmed that overall, the proportion of transmissions from men is increasing and is now at 63% of all transmissions in the area – even though a greater number of women are living with HIV than men.

The team say the disparity could be because men need to travel for work, that clinics are closed when they are back home, or for other reasons, including social stigma.

Dr Oliver Ratmann, senior author of the study from the Department of Mathematics at Imperial, said: “In this evolving battle against HIV, it is critical we adapt our strategies, bridge gaps in care, and ensure that individuals, regardless of their gender, have access to the lifesaving benefits of ART.

“It is important to design services in a way that everybody who would like to use them is able and feels empowered to do so. By routinely monitoring the changing dynamics of the epidemic and striving for equity in HIV care, we can move closer to the ultimate goal of controlling and, one day, eliminating HIV transmission.”

Dr Kate Grabowski, a co-author of the study from the Johns Hopkins School of Medicine, added: “The continued success of the President's Emergency Plan for AIDS Relief (PEPFAR) in reducing infections and saving lives is crucial for ending HIV transmission. With United States Congress currently evaluating PEPFAR funding, our evidence strongly supports the program's efficacy and provides a clear roadmap to ending the pandemic through enhanced HIV treatment coverage, particularly among men.”

Closing the gap in transmission

The team used data from the Rakai Community Cohort Study (RCCS) in southern Uganda, a region where more than 9% of adults are living with HIV – approximately 20 times higher than in the US. Since 2003, a period predating the widespread availability of ART in Africa, RCCS has enrolled nearly 37,000 individuals, tracking changes in HIV infection as new interventions came on board.

The analysis tracked evolving heterosexual HIV epidemic dynamics in 36 communities over a 15-year span of RCCS surveillance data, including records of new infections, deep sequence HIV genomic data, HIV treatment uptake, viral suppression, and behavioural information.

Analyses in earlier years showed that the highest number of new HIV cases in southern Uganda was among adolescent girls and young women aged 15-24 years. In more recent years tracked in the new study, women 25-34 years old have become a new focal group, experiencing a slower decline in new infections than other age groups. This is alongside a significant difference in the declines in new infections between men and women, with those among boys and men declining much faster.

To estimate the likely impact of getting men to the same level of viral suppression, the team applied statistical models based on the data about transmission dynamics. The resulting projections indicate that closing the viral suppression gap in men could have effectively halved rates of new infections among women and eliminated gender disparities in acquiring HIV.

Dr Joseph Kagaayi, previous director of the Rakai Health Sciences program and senior co-author of the study, said: “Our study findings emphasise the importance of addressing disparities in ART uptake and viral suppression between men and women. By doing so, we can not only reduce HIV infections among women but also work towards closing the gender gap in HIV transmission. Achieving these goals will require concerted efforts, informed policies, and strengthened healthcare services.”

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JOURNAL

Nature Microbiology

DOI

10.1038/s41564-023-01530-8 

ARTICLE TITLE

Longitudinal population-level HIV epidemiologic and genomic surveillance highlights growing gender disparity of HIV transmission in Uganda

ARTICLE PUBLICATION DATE

5-Dec-2023

 

Study reveals insights into tacking diabetic kidney disease - with a side order of how anti-obesity drugs work

How a new drug for diabetes gives clues to how anti-obesity drugs work

Peer-Reviewed Publication

MONASH UNIVERSITY

Data from Australian researchers could partly explain why a trial of a new drug for diabetes, was recently halted because it was found to be so effective. Importantly, the data also reveals how anti-obesity drugs like Ozempic, actually work, which to date have been a mystery.

In early November the FLOW trial of the drug semaglutide on the progression of renal impairment in people with type 2 diabetes and chronic kidney disease was halted ahead of schedule because of the drug’s efficacy.

Part of the rationale for the cessation of the trial could be explained by research led by Monash University’s Associate Professor Melinda Coughlan, and published today in the journal, Kidney International, showing that a drug that targets a particular hormone GLP1, also interacts with a receptor called RAGE, to control the kidney damage that is the hallmark of Type 2 diabetes.

The discovery of the importance of RAGE opens up new therapeutic drug targets for the prevention of kidney disease in people with diabetes. Diabetic kidney disease (DKD) occurs in up to 40% of individuals with diabetes. According to Associate Professor Coughlan, the outlook for DKD has improved over recent decades as a result of improved blood glucose control and blood pressure management through new therapies, “however, a significant proportion of individuals with diabetes will still progress to end stage kidney disease or die prematurely from a cardiovascular event,” she said.

“Our study opens up a way to potentially prevent kidney disease in those people who are, so far, treatment resistant.”

According to another co-author of the study, Professor Mark Cooper, also from Monash University’s Central Clinical School, the discovery of how the RAGE receptor works in diabetes, could also explain how the obesity drug, Ozempic, and similar drugs targeting obesity, work. “To date we know these drugs, which were developed to tackle diabetes, help with weight loss, however their mode of action has not been understood, particularly in reducing diabetic complications including kidney disease” he said.

“We know that the RAGE receptor promotes kidney injury but by blocking interactions between drugs such as Ozempic and this RAGE receptor we now have new information to expand and develop new drugs to protect the kidney.

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JOURNAL

Kidney International

DOI

10.1016/j.kint.2023.09.029 

ARTICLE TITLE

Glucagon-like peptide-1 receptor signaling modifies the extent of diabetic kidney disease through dampening the receptor for advanced glycation end products -induced inflammation

New cause of diabetes discovered, offering potential target for new classes of drugs to treat the disease

Peer-Reviewed Publication

CASE WESTERN RESERVE UNIVERSITY

 

IMAGE: 

JONATHAN STAMLER 

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CREDIT: CASE WESTERN RESERVE UNIVERSITY

 

Dec. 8, 2023

CLEVELAND—Researchers at Case Western Reserve University and University Hospitals have identified an enzyme that blocks insulin produced in the body—a discovery that could provide a new target to treat diabetes.

Their study, published Dec. 5 in the journal Cell, focuses on nitric oxide, a compound that dilates blood vessels, improves memory, fights infection and stimulates the release of hormones, among other functions. How nitric oxide performs these activities had long been a mystery.

The researchers discovered a novel “carrier” enzyme (called SNO-CoA-assisted nitrosylase, or SCAN) that attaches nitric oxide to proteins, including the receptor for insulin action.

They found that the SCAN enzyme was essential for normal insulin action, but also discovered heightened SCAN activity in diabetic patients and mice with diabetes. Mouse models without the SCAN enzyme appeared to be shielded from diabetes, suggesting that too much nitric oxide on proteins may be a cause of such diseases.

“We show that blocking this enzyme protects from diabetes, but the implications extend to many diseases likely caused by novel enzymes that add nitric oxide,” said the study’s lead researcher Jonathan Stamler, the Robert S. and Sylvia K. Reitman Family Foundation Distinguished Professor of Cardiovascular Innovation at the Case Western Reserve School of Medicine and president of Harrington Discovery Institute at University Hospitals. “Blocking this enzyme may offer a new treatment.”

Given the discovery, next steps could be to develop medications against the enzyme, he said.

The research team included Hualin Zhou and Richard Premont, both from Case Western Reserve School of Medicine and University Hospitals, and students Zack Grimmett and Nicholas Venetos from the university’s Medical Science Training Program.

Many human diseases, including Alzheimer’s, cancer, heart failure and diabetes, are thought to be caused or accelerated by nitric oxide binding excessively to key proteins. With this discovery, Stamler said, enzymes that attach the nitric oxide become a focus.

With diabetes, the body often stops responding normally to insulin. The resulting increased blood sugar stays in the bloodstream and, over time, can cause serious health problems. Individuals with diabetes, the Centers for Disease Control reports, are more likely to suffer such conditions as heart disease, vision loss and kidney disease.

But the reason that insulin stops working isn’t well understood.

Excessive nitric oxide has been implicated in many diseases, but the ability to treat has been limited because the molecule is reactive and can’t be targeted specifically, Stamler said.

“This paper shows that dedicated enzymes mediate the many effects of nitric oxide,” he said. “Here, we discover an enzyme that puts nitric oxide on the insulin receptor to control insulin. Too much enzyme activity causes diabetes. But a case is made for many enzymes putting nitric oxide on many proteins, and, thus, new treatments for many diseases.”

                                                            ###

Case Western Reserve University is one of the country's leading private research institutions. Located in Cleveland, we offer a unique combination of forward-thinking educational opportunities in an inspiring cultural setting. Our leading-edge faculty engage in teaching and research in a collaborative, hands-on environment. Our nationally recognized programs include arts and sciences, dental medicine, engineering, law, management, medicine, nursing and social work. About 6,200 undergraduate and 6,100 graduate students comprise our student body. Visit case.edu to see how Case Western Reserve thinks beyond the possible.

About University Hospitals / Cleveland, Ohio
Founded in 1866, University Hospitals serves the needs of patients through an integrated network of 21 hospitals (including five joint ventures), more than 50 health centers and outpatient facilities, and over 200 physician offices in 16 counties throughout northern Ohio. The system’s flagship quaternary care, academic medical center, University Hospitals Cleveland Medical Center, is affiliated with Case Western Reserve University School of Medicine, Northeast Ohio Medical University, Oxford University, the Technion Israel Institute of Technology and National Taiwan University College of Medicine. The main campus also includes the UH Rainbow Babies & Children's Hospital, ranked among the top children’s hospitals in the nation; UH MacDonald Women's Hospital, Ohio's only hospital for women; and UH Seidman Cancer Center, part of the NCI-designated Case Comprehensive Cancer Center. UH is home to some of the most prestigious clinical and research programs in the nation, with more than 3,000 active clinical trials and research studies underway. UH Cleveland Medical Center is perennially among the highest performers in national ranking surveys, including “America’s Best Hospitals” from U.S. News & World Report. UH is also home to 19 Clinical Care Delivery and Research Institutes. UH is one of the largest employers in Northeast Ohio with more than 30,000 employees. Follow UH on LinkedIn, Facebook and Twitter. For more information, visit UHhospitals.org.

 

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JOURNAL

Cell

DOI

10.1016/j.cell.2023.11.009 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

An enzyme that selectively S-nitrosylates proteins to regulate insulin signaling

ARTICLE PUBLICATION DATE

5-Dec-2023

 

When is an aurora not an aurora?

Phenomena called “Steve” and “picket fence” are masquerading as auroras, graduate student argues

Peer-Reviewed Publication

UNIVERSITY OF CALIFORNIA - BERKELEY

 

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A NORMAL AURORA (LEFT) CONSISTS OF GLOWING CURTAINS OF RED, GREEN AND BLUE. AN ENHANCED AURORA (RIGHT) CONTAINS A THIN, BRIGHTER LAYER WHICH EXHIBITS MUCH MORE GREEN, POSSIBLY CAUSED BY THE SAME PHYSICAL PROCESS THAT CREATES STEVE AND THE PICKET FENCE. BECAUSE ENHANCED AURORAS ARE MORE COMMON, UC BERKELEY RESEARCHERS PLAN TO PROBE THEM FIRST TO DETERMINE WHAT CONDITIONS IN THE UPPER ATMOSPHERE CAUSE THE PHENOMENA.

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CREDIT: VINCENT LEDVINA, THEAURORAGUY.COM

The shimmering green, red and purple curtains of the northern and southern lights — the auroras — may be the best-known phenomena lighting up the nighttime sky, but the most mysterious are the mauve and white streaks called Steve and their frequent companion, a glowing green "picket fence."

First recognized in 2018 as distinct from the common auroras, Steve — a tongue-in-cheek reference to the benign name given a scary hedge in a 2006 children's movie — and its associated picket fence were nevertheless thought to be caused by the same physical processes. But scientists were left scratching their heads about how these glowing emissions were produced.

Claire Gasque, a University of California, Berkeley, graduate student in physics, has now proposed a physical explanation for these phenomena that is totally different from the processes responsible for the well-known auroras. She has teamed up with researchers at the campus's Space Sciences Laboratory (SSL) to propose that NASA launch a rocket into the heart of the aurora to find out if she's correct.

Vibrant auroras and glowing phenomena such as Steve and the picket fence are becoming more common as the sun enters the active period of its 11-year cycle, and November was a good month for Steve observations in the northern latitudes. Because all these transient luminous phenomena are triggered by solar storms and coronal mass ejections from the sun, the approaching solar maximum is an ideal time to study rare events like Steve and the picket fence.

Gasque described the physics behind the picket fence in a paper published last month in the journal Geophysical Research Letters and will discuss the results on Dec. 14 in an invited talk at the American Geophysical Union meeting in San Francisco.

She calculated that in a region of the upper atmosphere farther south than that in which auroras form, electric fields parallel to Earth's magnetic field could produce the color spectrum of the picket fence. If correct, this unusual process has implications for how physicists understand energy flow between Earth's magnetosphere, which surrounds and protects Earth from the solar wind, and the ionosphere at the edge of space.

"This would upend our modeling of what creates light and the energy in the aurora in some cases," Gasque said.

"The really interesting thing about Claire's paper is that we've known for a couple of years now that the Steve spectrum is telling us there's some very exotic physics going on. We just didn't know what it was," said Brian Harding, a co-author of the paper and an SSL assistant research physicist. "Claire's paper showed that parallel electric fields are capable of explaining this exotic spectrum."

The paper was a side project from Gasque's Ph.D. thesis, which is focused on the connection between events like volcanoes on Earth's surface and phenomena in the ionosphere 100 kilometers or more above our heads.

But after hearing about Steve — which has now become an acronym for Strong Thermal Emission Velocity Enhancement — at a conference in 2022, she couldn't resist looking into the physics behind Steve and the picket fence.

"It's really cool," she said. "It's one of the biggest mysteries in space physics right now."

The physics of Steve and picket fence

The common auroras are produced when the solar wind energizes particles in Earth's magnetosphere, often at altitudes higher than 1,000 kilometers above the surface. These energized particles spiral around Earth's magnetic field lines toward the poles, where they crash into and excite oxygen and nitrogen molecules in the upper atmosphere. When those molecules relax, oxygen emits specific frequencies of green and red light, while nitrogen generates a bit of red, but primarily a blue, emission line.

The colorful, shimmering curtains that result can extend for thousands of kilometers across the northern or southern latitudes.

Steve, however, displays not individual emission lines, but a broad range of frequencies centered around purple or mauve. And unlike auroras, neither Steve nor the picket fence emit blue light, which is generated when the most energetic particles hit and ionize nitrogen. Steve and the picket fence also occur at lower latitudes than the aurora, potentially even as far south as the equator.

Some researchers proposed that Steve is caused by ion flows in the upper atmosphere, referred to as subauroral ion drift, or SAID, though there's no well accepted physical explanation for how SAID could generate the colorful emissions.

Gasque's interest was sparked by suggestions that the picket fence's emissions could be generated by low-altitude electric fields parallel to Earth's magnetic field, a situation thought to be impossible because any electric field aligned with the magnetic field should quickly short out and disappear.

Using a common physical model of the ionosphere, Gasque subsequently showed that a moderate parallel electric field — around 100 millivolts per meter — at a height of about 110 km could accelerate electrons to an energy that would excite oxygen and nitrogen and generate the spectrum of light observed from the picket fence. Unusual conditions in that area, such as a lower density of charged plasma and more neutral atoms of oxygen and nitrogen, could potentially act as insulation to keep the electric field from shorting out.

"If you look at the spectrum of the picket fence, it's much more green than you would expect. And there's none of the blue that's coming from the ionization of nitrogen," Gasque said. "What that's telling us is that there's only a specific energy range of electrons that can create those colors, and they can't be coming from way out in space down into the atmosphere, because those particles have too much energy."

Instead, she said, "the light from the picket fence is being created by particles that have to be energized right there in space by a parallel electric field, which is a completely different mechanism than any of the aurora that we've studied or known before."

She and Harding suspect that Steve itself may be produced by related processes. Their calculations also predict the type of ultraviolet emissions that this process would produce, which can be checked to verify the new hypothesis about the picket fence.

Though Gasque's calculations don't directly address the on-off glow that makes the phenomenon look like a picket fence, it's likely due to wavelike variations in the electric field, she said. And while the particles that are accelerated by the electric field are probably not from the sun, the scrambling of the atmosphere by solar storms probably triggers Steve and the picket fence, as it does the common aurora.

Enhanced auroras exhibit a picket fence-like glow

The next step, Harding said, is to launch a rocket from Alaska through these phenomena and measure the strength and direction of the electric and magnetic fields. SSL scientists specialize in designing and building instruments that do just that. Many of these instruments are on spacecraft now orbiting Earth and the sun.

Initially, the target would be what's known as an enhanced aurora, which is a normal aurora with picket fence-like emissions embedded in it.

"The enhanced aurora is basically this bright layer that's embedded in the normal aurora. The colors are similar to the picket fence in that there's not as much blue in them, and there's more green from oxygen and red from nitrogen. The hypothesis is that these are also created by parallel electric fields, but they are a lot more common than the picket fence," Gasque said.

The plan is not only "to fly a rocket through that enhanced layer to actually measure those parallel electric fields for the first time," she said, but also send a second rocket up to measure the particles at higher altitudes, "to distinguish the conditions from those that cause the auroras." Eventually, she hopes for a rocket that will fly directly through Steve and the picket fence.

Harding, Gasque and colleagues proposed just such a sounding rocket campaign to NASA this fall and expect to hear back regarding its selection in the first half of 2024. Gasque and Harding consider the experiment an important step in understanding the chemistry and physics of the upper atmosphere, the ionosphere and Earth’s magnetosphere, and a proposal in line with the Low Cost Access to Space (LCAS) program sponsored by NASA for projects like this.

"It's fair to say that there's going to be a lot of study in the future about how those electric fields got there, what waves they are or aren't associated with, and what that means for the larger energy transfer between Earth's atmosphere and space," Harding said. "We really don't know. Claire's paper is the first step in the chain of that understanding."

Gasque expressed appreciation for the input from people who study the middle ionosphere, or mesosphere, and the stratosphere, whose ideas helped her puzzle out the solution.

"With this collaboration, we were able to make some really cool progress in this field," she said. "Honestly, it was just following our nose and being excited about it."

In addition to Harding, her other co-authors are Reza Janalizadeh of Pennsylvania State University in University Park, Justin Yonker of the Applied Physics Laboratory at Johns Hopkins University in Laurel, Maryland, and D. Megan Gillies of the University of Calgary in Alberta, Canada.

Partial support for this work was provided by the National Science Foundation (AGS-2010088), National Aeronautics and Space Administration (80NSSC21K1386) and Robert P. Lin Fellowship at UC Berkeley.

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JOURNAL

Geophysical Research Letters

DOI

10.1029/2023GL106073 

METHOD OF RESEARCH

Computational simulation/modeling

ARTICLE TITLE

It's Not Easy Being Green: Kinetic Modeling of the Emission Spectrum Observed in STEVE's Picket Fence

 

First hints of nuclear fission in cosmos revealed by models, observations

Fission models find clear fingerprints of nuclear process never before directly observed in stars

Peer-Reviewed Publication

DOE/LOS ALAMOS NATIONAL LABORATORY

 

IMAGE: 

THE MERGER OF TWO NEUTRON STARS IS AMONG THE LEADING CANDIDATE SITES FOR SYNTHESIZING THE HEAVIER ELEMENTS ON THE PERIODIC TABLE THROUGH THE RAPID-NEUTRON-CAPTURE PROCESS. THE IMAGE SHOWS TWO NEUTRON STARS COLLIDING TO RELEASING NEUTRONS THAT RADIOACTIVE NUCLEI RAPIDLY CAPTURE. THE COMBINATION OF NEUTRON CAPTURE AND RADIOACTIVE DECAY PRODUCES SUBSEQUENTLY HEAVIER ELEMENTS. THE ENTIRE PROCESS IS BELIEVED TO HAPPEN IN A SINGLE SECOND.

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CREDIT: CREDIT: LOS ALAMOS NATIONAL LABORATORY (MATTHEW MUMPOWER)

LOS ALAMOS, N.M., Dec. 7, 2023 — The elements above iron on the periodic table are thought to be created in cataclysmic explosions like the merger of two neutron stars or in rare classes of supernovae. New research suggests fission may operate in the cosmos during the creation of the heavy elements. Combing through data on a variety of elements that reside in very old stars, researchers have found a potential signature of fission, indicating that nature is likely to produce superheavy nuclei beyond the heaviest elements on the periodic table.

“People have thought fission was happening in the cosmos, but to date, no one has been able to prove it,” said Matthew Mumpower, a theoretical physicist at Los Alamos National Laboratory and co-author of a paper in Science presenting the research.

Using the latest observations, Mumpower said, the researchers found a correlation between light precision metals like silver and rare earth nuclei like europium. When one of these groups of elements goes up, the corresponding elements in the other group also increase — the correlation is positive.

‘Incredibly profound” evidence of fission

“The only plausible way this can arise among different stars is if there is a consistent process operating during the formation of the heavy elements,” Mumpower said. The team tested all the possibilities and fission was the only explanation that was able to reproduce the trend.

“This is incredibly profound and is the first evidence of fission operating in the cosmos, confirming a theory we proposed several years ago,” Mumpower said. “As we’ve acquired more observations, the cosmos is saying hey, there’s a signature here, and it can only come from fission.”

The research also indicates that elements with an atomic mass (the number of protons plus neutrons) of 260 — heavier than those charted at the high end of the periodic table — may exist.

Mumpower developed the fission models used to predict and guide the observational findings, which were led by study author Ian Roederer of North Carolina State University.

Heavy research

Astrophysicists have long believed heavy elements beyond iron were formed in stellar explosions called supernova or when two neutron stars merged. As the name implies, the latter are composed largely of neutrons, which together with protons form the nuclei of all atoms. Through the rapid-neutron capture process, dubbed the r-process, atomic nuclei grab neutrons to form heavier elements. Whether some grow too heavy to hold together and split, or fission, forming two atoms of lighter but still heavy elements (and releasing tremendous energy) has remained a mystery for a half century. 

In a 2020 paper, Mumpower first predicted the distributions of fission fragments for r-process nuclei. A subsequent study led by collaborator Nicole Vassh at TRIUMF predicted the co-production of light precision metals and rare earth nuclei. This co-production of elements like elements ruthenium, rhodium, palladium and silver, and those like europium, gadolinium, dysprosium and holmium, can be tested by comparing the prediction with elemental abundances in a collection of stars.

The new analysis led by Roederer combed through observational data from 42 stars and found precisely the predicted correlation. The pattern provides a clear signature of fission creating these elements and a similar pattern of elements slightly heavier and higher on the periodic table.

“The correlation is very robust in r-process enhanced stars where we have sufficient data. Every time nature produces an atom of silver, it’s also producing heavier rare earth nuclei in proportion. The composition of these element groups are in lock step,” Mumpower said. “We have shown that only one mechanism can be responsible — fission — and people have been racking brains about this since the 1950s.”

From stockpile stewardship to the stars

“At Los Alamos, we developed nuclear fission models because we can’t measure everything that’s relevant for weapons research as part of the Laboratory’s mission,” Mumpower said. The models allow physicists to interpret experiments and fill in data when measurements are lacking. Since the United States halted testing of nuclear weapons in 1992, experimental data on fission has been limited.

The models perform exceptionally well when compared to measured data and thus give credence to their extrapolations where there are no measurements. The nuclear inputs of both short-lived and long-lived species are required for studies of heavy element formation, Mumpower said. Fission yields are products of the process of splitting relatively heavy atoms into lighter ones — the same process used in nuclear weapons and reactors.

 

The paper: “Element abundance patterns in stars indicate fission of nuclei heavier than uranium.” Science. DOI:  10.1126/science.adf1341

  

The funding: Laboratory Directed Research and Development program at Los Alamos National Laboratory.

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LA-UR-23-33647

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JOURNAL

Science

DOI

10.1126/science.adf1341 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Element abundance patterns in stars indicate fission of nuclei heavier than uranium

ARTICLE PUBLICATION DATE

8-Dec-2023