Structure-based Protein Design Advances Vaccine Development for Human Metapneumovirus

When the U.S. Centers for Disease Control and Prevention began investigating several cases of severe respiratory illnesses around the state of North Dakota in 2016, they uncovered the presence of a serious and potentially life-threatening virus known as human metapneumovirus (hMPV). Within four hospitals across the state, 44 cases of hMPV were uncovered impacting both children (17) and adults (27). And although many healthy populations are not severely impacted by hMPV, five of the patients from this outbreak―including two children, succumbed to the illness. hMPV like COVID-19, which would surface only three short years later, and other transient viruses suffer from the same problem: a lack of information. The cases in North Dakota show that hMPV can have serious health implications for some patient populations, but the lack of understanding about this virus, and countless others, means that there are no vaccines or therapeutics available to help protect at-risk groups. Fortunately, this issue is starting to change. In a recent study published in Nature Communications, a team of researchers carrying out experiments at the U.S. Department of Energy’s Advanced Photon Source (APS) have isolated and characterized highly stable hMPV fusion (f) proteins that are critical for viral entry. The insights reported not only provide the structure-function relationship of these fusion proteins, but also highlight the potential for these proteins to advance the development of hMPV vaccines and therapeutics.

COVID-19, which has resulted in the death of more than 6.6 million people around the world, has brought dialogue about vaccines and immunity back to the forefront of public conversation. And although devastating viral infections like polio, hepatitis A&B, Haemophilus influenzae type B, measles, and mumps have essentially been erased from the U.S. vernacular due to successful vaccination programs, few people are aware that many debilitating and long-standing viral pathogens, like chikungunya virus, Dengue virus, eastern equine encephalitis virus, cytomegalovirus, respiratory syncytial virus and a number of other viruses still lack the basic research to develop adequate vaccines and therapeutics.

Similarly, the devastating hMPV virus that struck North Dakota in 2016 lacked the basic research information for vaccine development and remains without a vaccine in 2022.

Read more on the APS website

Image: Fig. 1. Crystal structure of perfusion-stabilized hMPV F (DS-CavES2) made with ChimeraX with substitutions shown as spheres, determined at SBC-XSD.

Trigger of rare blood clots with AstraZeneca and other COVID vaccines found by scientists

understanding rare blood clots caused by some  COVID vaccines – important first to prevention

A collaborative team from the School of Medicine at the University of Cardiff, Wales and a range of US institutions used the UK’s national synchrotron, Diamond Light Source, to help reveal the details of how a protein in the blood is attracted to a key component of Adenovirus based vaccines.  

It is believed this protein kicks off a chain reaction, involving the immune system, that can culminate in extremely rare but dangerous blood clots. The Cardiff team were given emergency government funding to find the answers. In collaboration with scientists in the US and from AstraZeneca, they set out to collect data on the structure of the vaccines and perform computer simulations and related experiments to try and uncover why some of the vaccines based on Adenoviruses were causing blood clots in rare cases.  

Moderna and BioNTech are based on mRNA, whereas AstraZeneca and Johnson & Johnson are based on Adenoviruses. Blood clots have only been associated with vaccines that use Adenoviruses.

Read more on the Diamond website

Image: Crystallisation of ChAdOx1 fibre-knob protein results in 4 copies of the expected trimer per asymmetric unit and reveals side-chain locations. The crystal structure was solved with 12 copies of the monomer in the asymmetric unit, packing to form 3 trimeric biological assemblies. Density was sufficient to provide a complete structure in all copies.

Credit: Image reused from DOI: 10.1126/sciadv.abl8213 under the CC BY 2.0 license. 

A novel approach offers hope for an HCV vaccine

An HCV vaccine is needed, but hard to develop. A structural mimic may be the key to enhancing our immune response

Globally, more than 70 million people were struggling with a chronic hepatitis C virus (HCV) infection in 2015. Although effective drugs are available to treat chronic infections, only 13% of cases received curative treatment. The fact that only 20% have been diagnosed is of even greater concern. Although a minority of newly-infected individuals (10–40%) manage to overcome the disease, most develop a chronic infection. Most acute cases of HCV are asymptomatic, leading to undetected virus transmission. Left untreated chronic HCV can lead to serious liver damage and an increased risk of liver cancer. As curative therapies alone cannot eliminate the virus, a vaccine is required. However, because HCV is very diverse and evolves rapidly to evade the immune system, developing an effective vaccine is challenging. In work recently published in npj Vaccines, scientists from the MRC-University of Glasgow Centre for Virus Research, the University of St. Andrews and Imperial College London describe an alternative strategy that uses a structural mimic to encourage the immune system to make antibodies that can recognise multiple strains of the virus i.e. broadly-neutralising antibodies (bNAbs) against HCV. 

A moving target

With its high genetic diversity and an envelope of ever-changing glycoproteins, HCV is challenging for the human immune system to detect and counteract. The minority of cases in which the virus is successfully cleared from the body show a broad, strong T-cell response and neutralising antibodies during the early phase of infection. Individuals who have previously cleared an HCV infection have an 80% chance of successfully fighting off reinfection, indicating that a protective immune response has been induced and that vaccination is a realistic goal. However, with seven distinct genotypes and more than 60 subtypes, the genetic variation makes it challenging to produce a vaccine that would protect against all infections. 

Read more on the Diamond website

Image: I03 beamline at Diamond

Credit: Diamond Light Source

Pirbright Institute grants a new licence for FMDV vaccine development

The Pirbright Institute and its research partners have granted MSD Animal Health an exclusive commercial licence for a new, effective and affordable vaccine to protect livestock against several serotypes of foot-and-mouth disease virus (FMDV). The new vaccine is more stable than current foot-and-mouth disease (FMD) vaccines and is less reliant on a cold-chain during vaccine distribution – characteristics that give the vaccine greater potential for helping to relieve the burden placed on regions where the disease is endemic in large parts of Africa, the Middle East and Asia. These developments have been possible, thanks to a long-standing collaboration between Diamond Light Source, Pirbright, the University of Oxford, the University of Reading and MSD Animal Health, and the vaccine has been developed over the years from basic science to animal trials. This work has been supported by funding from the Wellcome Trust to speed up commercialisation.

Professor David Stuart, Life Sciences Director at Diamond Light Source and MRC Professor in Structural Biology at the University of Oxford, noted:

We have been working to achieve something close to the holy grail of vaccines. Instead of traditional methods of vaccine development, using infectious virus as its basis, our team synthetically created empty protein shells to imitate the protein coat that forms the strong outer layer of the virus. Diamond’s visualisation capabilities and the expertise of Oxford University in structural analysis and computer simulation, enabled us to visualise in detail something invisible in a normal microscope and to enhance the design, atom by atom, of the empty shells. The key thing is that unlike the traditional FMDV vaccines, there is no chance that the empty shell vaccine could revert to an infectious form. The licence that has just been granted suggests that the work will have a broad and enduring impact on vaccine development.

>Read more on the Diamond Light Source website

Winning the fight against influenza

Annual influenza epidemics and episodic pandemics continue to cause widespread illness and mortality. The World Health Organization estimates that annual influenza epidemics cause around 3–5 million cases of severe illness and up to 650,000 deaths worldwide. Seasonal influenza vaccination still remains the best strategy to prevent infection, but the vaccines that are available now offer a very limited breadth of protection. Human broadly neutralizing antibodies (bnAbs) that bind to the hemagglutinin (HA) stem region provide hope for a universal vaccine (Figure 1a)1,2. Binding of these bnAbs prevents the pH-induced conformational changes that are required for viral fusion in the endosomal compartments of target cells in the respiratory tract and, hence, viral entry in our cells.

>Read more on the SSRL at SLAC website

Image: Complex of Influenza virus HA with (a) Fab CR6261, (b) llama single domain antibody SD36, and (c) JNJ4796.

Targeting bacteria that cause meningitis and sepsis

The work provides molecular-level information about how the antibody confers broad immunity against a variable target and suggests strategies for further improvement of available vaccines.

Our central nervous systems (brain and spinal cord) are surrounded by three membranes called “meninges.” Meningitis is caused by the swelling of these membranes, resulting in headache, fever, and neck stiffness. Most cases of meningitis in the United States are the result of viral infections and are relatively mild. However, meningitis caused by bacterial infection, if left untreated, can be deadly or lead to serious complications, including hearing loss and neurologic damage.

The bacterium responsible for meningitis (Neisseria meningitidis) can also infect the bloodstream, causing another life-threatening condition known as sepsis. N. meningitidis is spread through close contact (coughing or kissing) or lengthy contact (e.g. in dorm rooms or military barracks). In this work, researchers were interested in understanding how humans develop immunity to bacterial meningitis and sepsis, collectively known as meningococcal disease, by vaccination with a new protein-based vaccine.

>Read more on the Advanced Light Source website

Image: The work provides molecular-level information about how the antibody confers broad immunity against a variable target and suggests strategies for further improvement of available vaccines.

Structures reveal new target for malaria vaccine

The discovery paves the way for the development of a more effective and practical human vaccine for malaria, a disease responsible for half a million deaths worldwide each year.

Malaria kills about 445,000 people a year, mostly young children in sub-Saharan Africa, and sickens more than 200 million. It’s caused by a parasite, Plasmodium falciparum (Pf), and is spread to humans through the bite of an infected Anopheles mosquito.

The parasite’s complex life cycle and rapid mutations have long challenged vaccine developers. Only one experimental vaccine, known as RTS,S, has progressed to a Phase 3 clinical trial (testing on large groups of people for efficacy and safety). To elicit an immune response, this vaccine uses a fragment of circumsporozoite protein (CSP), which covers the malaria parasite in its native conformation. However, the trial results showed that RTS,S is only moderately effective, protecting about one-third of the young children who received it over a period of four years.

>Read more on the Advanced Light Source website.

Image (a) Left: Surface representation of CIS43 (light chain in tan and heavy chain in light blue), with peptide 21 shown as sticks (purple). Right: A 90° rotation of the representation. See entire image here.

Respiratory virus study points to likely vaccine target

Fighting malaria with X-rays

Today 25 April, is World Malaria Day.

Considered as one of humanity’s oldest life-threatening diseases, nearly half the world population is at risk, with 216 million people affected in 91 countries worldwide in 2016. Malaria causes 445 000 deaths every year, mainly among children. The ESRF has been involved in research into Malaria since 2005, with different techniques being used in the quest to find ways to prevent or cure the disease.

Malaria in humans is caused by Plasmodium parasites, the greatest threat coming from two species: P. falciparum and P. vivax. The parasites are introduced through the bites of infected female Anopheles mosquitoes. They travel to the liver where they multiply, producing thousands of new parasites. These enter the blood stream and invade red blood cells, where they feed on hemoglobin (Hgb) in order to grow and multiply. After creating up to 20 new parasites, the red blood cells burst, releasing daughter parasites ready for new invasions. This life cycle leads to an exponential growth of infected red blood cells that may cause the death of the human host.

The research carried out over the years at the ESRF has aimed to identify mechanisms critical for the parasite’s survival in the hope of providing an intelligent basis for the development of drugs to stop the parasite’s multiplication and spread.

>Read more on the European Synchrotron website

Image: Inside the experimental hutch of the ESRF’s ID16A nano-analysis beamlin.
Credit: Pierre Jayet

The search for an Ebola vaccine

Researchers expertly solved the crystal structures of drugs bound to the outer coating of the Ebola virus to pinpoint the regions that are essential for inhibitory activity.

Ebola is a viral disease that is highly infectious and associated with a high risk of death. It first arose in 1976, from which point it was associated with dozens of small-scale outbreaks; however, in 2013 Ebola was responsible for a huge epidemic in West Africa. Emergency was declared and over 11,000 people lost their lives to the virus. Despite this horrific state of affairs, Ebola still remains an untreatable disease and there is no vaccine to prevent infection.

>Read more on the Diamond Light Source website


Crystallographers identify 1,000 protein structures

The Canadian Light Source is celebrating two milestones reached by scientists who have conducted research at the national facility at the University of Saskatchewan.

Scientists have solved 1,000 protein structures using data collected at CLS’s CMCF beamlines. These have been added to the Protein Data Bank – a collection of structures solved by researchers globally. Researchers have also published 500 scientific papers based on their work using the crystallography beamlines.

Proteins are the building blocks of life and are described as the body’s workhorses. The body is made of trillions of cells. Cells produce proteins, which do the work of breaking down food, sending messages to other cells, and fighting bacteria, viruses and parasites. The discoveries at the CLS range from how the malaria parasite invades red blood cells to why superbugs are resistant to certain antibiotics and how parkin protein mutations result in some types of Parkinson’s disease. Understanding how these and other such proteins work can potentially save millions of lives.

>Read more on the Canadian Light Source website

Image: PDB ID: 6B0S


World Polio Day

Are we nearing the end of the war on polio?

There was a time when the word itself was enough to strike fear into the hearts of people around the world. Polio: a highly infectious virus that could shatter young lives in the blink of an eye. On the 24th of October, we mark World Polio Day, and this is something worth celebrating. Because whilst the story isn’t over yet, it may well be nearing its end.

Polio has been around since before records began, but it wasn’t until the early-twentieth century that epidemics began to sweep through communities in Europe and America, affecting many thousands of children and families.

It’s hard to underestimate the terror once caused by polio. At its height in the 1950s, parents routinely lived in fear of their children becoming quarantined, paralysed or even worse. It was a dark time in medical history but, despite this, polio really is a success story for modern science.

Growing a better polio vaccine

Researchers use plants as factories to produce a safer polio vaccine

Successful vaccination campaigns have reduced the number of polio cases by over 99% in the last several decades. However, producing the vaccines entails maintaining a large stock of poliovirus, raising the risk that the disease may accidentally be reintroduced.
Outbreaks can also occur due to mutation of the weakened poliovirus used in the oral vaccine. In addition, the oral vaccine has to be stored at cold temperatures. To address these shortcomings, an international team of researchers across the UK has engineered plants that produce virus-like particles derived from poliovirus, which can serve as a vaccine.
They report the success of this approach in a paper appearing in Nature Communications. The team confirmed the structure of the virus-like particles by cryo-electron microscopy at Diamond Light Source’s Electron Bio-Imaging Centre (eBIC) and showed that the particles effectively protected mice from infection with poliovirus. This proof-of-principle study demonstrates that a safe, effective polio vaccine can be produced in plants and raises the possibility of using the same approach to tackle other viruses.

From Community to Molecule – on Track Towards a Zika Vaccine

A potent new weapon against the Zika virus in the blood of people who have been infected by it.

A research team based at The Rockefeller University has identified a potent new weapon against the Zika virus in the blood of people who have been infected by it. This discovery could lead to new ways of fighting the disease. Detailed examination of the interaction between the virus and antibodies derived from human subjects in Brazil and Mexico, including crystallographic studies performed at the Stanford Synchrotron Radiation Lightsourse (SSRL), have revealed a new potential strategy for developing a vaccine towards this virus.

Through collaborators working in Pau da Lima, Brazil, and Santa Maria Mixtequilla, Mexico, the research team obtained blood samples from more than 400 people, collected shortly after Zika was circulating.

In these samples, antibodies that block the virus from initiating an infection were found. Interestingly, the antibodies appeared to have been initially generated in response to an earlier infection by a related virus (DENV1) that causes dengue fever. It appears that, much like a vaccine, the DENV1 virus can prime the immune system to respond to Zika.