Experimental mRNA Vaccine May Protect Against All 20 Influenza Virus Subtypes
Posted on by Lawrence Tabak, D.D.S., Ph.D.
Flu season is now upon us, and protecting yourself and loved ones is still as easy as heading to the nearest pharmacy for your annual flu shot. These vaccines are formulated each year to protect against up to four circulating strains of influenza virus, and they generally do a good job of this. What they can’t do is prevent future outbreaks of more novel flu viruses that occasionally spill over from other species into humans, thereby avoiding a future influenza pandemic.
On this latter and more-challenging front, there’s some encouraging news that was published recently in the journal Science . An NIH-funded team has developed a unique “universal flu vaccine” that, with one seasonal shot, that has the potential to build immune protection against any of the 20 known subtypes of influenza virus and protect against future outbreaks.
While this experimental flu vaccine hasn’t yet been tested in people, the concept has shown great promise in advanced pre-clinical studies. Human clinical trials will hopefully start in the coming year. The researchers don’t expect that this universal flu vaccine will prevent influenza infection altogether. But, like COVID-19 vaccines, the new flu vaccine should help to reduce severe influenza illnesses and deaths when a person does get sick.
So, how does one develop a 20-in-1“multivalent” flu vaccine? It turns out that the key is the same messenger RNA (mRNA) technology that’s enabled two of the safe and effective vaccines against COVID-19, which have been so instrumental in fighting the pandemic. This includes the latest boosters from both Pfizer and Moderna, which now offer updated protection against currently circulating Omicron variants.
While this isn’t the first attempt to develop a universal flu vaccine, past attempts had primarily focused on a limited number of conserved antigens. An antigen is a protein or other substance that produces an immune response. Conserved antigens are those that tend to stay the same over time.
Because conserved antigens will look similar in many different influenza viruses, the hope was that vaccines targeting a small number of them would afford some broad influenza protection. But the focus on a strategy involving few antigens was driven largely by practical limitations. Using traditional methods to produce vaccines by growing flu viruses in eggs and isolating proteins, it simply isn’t feasible to include more than about four targets.
That’s where recent advances in mRNA technology come in. What makes mRNA so nifty for vaccines is that all you need to know is the letters, or sequence, that encodes the genetic material of a virus, including the sequences that get translated into proteins.
A research team led by Scott Hensley, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, recognized that the ease of designing and manufacturing mRNA vaccines opened the door to an alternate approach to developing a universal flu vaccine. Rather than limiting themselves to a few antigens, the researchers could make an all-in-one influenza vaccine, encoding antigens from every known influenza virus subtype.
Influenza vaccines generally target portions of a plentiful protein on the viral surface known as hemagglutinin (H). In earlier work, Hensley’s team, in collaboration with Perelman’s mRNA vaccine pioneer Drew Weissman, showed they could use mRNA technology to produce vaccines with H antigens from single influenza viruses [2, 3]. To protect the fragile mRNA molecules that encode a selected H antigen, researchers deliver them to cells inside well-tolerated microscopic lipid shells, or nanoparticles. The same is true of mRNA COVID-19 vaccines. In their earlier studies, the researchers found that when an mRNA vaccine aimed at one flu virus subtype was given to mice and ferrets in the lab, their cells made the encoded H antigen, eliciting protective antibodies.
In this latest study, they threw antigens from all 20 known flu viruses into the mix. This included H antigens from 18 known types of influenza A and two lineages of influenza B. The goal was to develop a vaccine that could teach the immune system to recognize and respond to any of them.
More study is needed, of course, but early indications are encouraging. The vaccine generated strong and broad antibody responses in animals. Importantly, it worked both in animals with no previous immunity to the flu and in those previously infected with flu viruses. That came as good news because past infections and resulting antibodies sometimes can interfere with the development of new antibodies against related viral subtypes.
In more good news, the researchers found that vaccinated mice and ferrets were protected against severe illness when later challenged with flu viruses. Those viruses included some that were closely matched to antigens in the vaccine, along with some that weren’t.
The findings offer proof-of-principle that mRNA vaccines containing a wide range of antigens can offer broad protection against influenza and likely other viruses as well, including the coronavirus strains responsible for COVID-19. The researchers report that they’re moving toward clinical trials in people, with the goal of beginning an early phase 1 trial in the coming year. The hope is that these developments—driven in part by technological advances and lessons learned over the course of the COVID-19 pandemic—will help to mitigate or perhaps even prevent future pandemics.
 A multivalent nucleoside-modified mRNA vaccine against all known influenza virus subtypes. Arevalo CP, Bolton MJ, Le Sage V, Ye N, Furey C, Muramatsu H, Alameh MG, Pardi N, Drapeau EM, Parkhouse K, Garretson T, Morris JS, Moncla LH, Tam YK, Fan SHY, Lakdawala SS, Weissman D, Hensley SE. Science. 2022 Nov 25;378(6622):899-904.
 Nucleoside-modified mRNA vaccination partially overcomes maternal antibody inhibition of de novo immune responses in mice. Willis E, Pardi N, Parkhouse K, Mui BL, Tam YK, Weissman D, Hensley SE. Sci Transl Med. 2020 Jan 8;12(525):eaav5701.
 Nucleoside-modified mRNA immunization elicits influenza virus hemagglutinin stalk-specific antibodies. Pardi N, Parkhouse K, Kirkpatrick E, McMahon M, Zost SJ, Mui BL, Tam YK, Karikó K, Barbosa CJ, Madden TD, Hope MJ, Krammer F, Hensley SE, Weissman D. Nat Commun. 2018 Aug 22;9(1):3361.
Understanding Flu Viruses (Centers for Disease Control and Prevention, Atlanta)
COVID Research (NIH)
Decades in the Making: mRNA COVID-19 Vaccines (NIH)
Video: mRNA Flu Vaccines: Preventing the Next Pandemic (Penn Medicine, Philadelphia)
Scott Hensley (Perelman School of Medicine at the University of Pennsylvania, Philadelphia)
Weissman Lab (Perelman School of Medicine)
Video: The Story Behind mRNA COVID Vaccines: Katalin Karikó and Drew Weissman (Penn Medicine, Philadelphia)
NIH Support: National Institute for Allergy and Infectious Diseases
‘Decoy’ Protein Works Against Multiple Coronavirus Variants in Early Study
Posted on by Lawrence Tabak, D.D.S., Ph.D.
The NIH continues to support the development of some very innovative therapies to control SARS-CoV-2, the coronavirus that causes COVID-19. One innovative idea involves a molecular decoy to thwart the coronavirus.
How’s that? The decoy is a specially engineered protein particle that mimics the 3D structure of the ACE2 receptor, a protein on the surface of our cells that the virus’s spike proteins bind to as the first step in causing an infection.
The idea is when these ACE2 decoys are administered therapeutically, they will stick to the spike proteins that crown the coronavirus (see image above). With its spikes covered tightly in decoy, SARS-CoV-2 has a more-limited ability to attach to the real ACE2 and infect our cells.
Recently, the researchers published their initial results in the journal Nature Chemical Biology, and the early data look promising . They found in mouse models of severe COVID-19 that intravenous infusion of an engineered ACE2 decoy prevented lung damage and death. Though more study is needed, the researchers say the decoy therapy could potentially be delivered directly to the lungs through an inhaler and used alone or in combination with other COVID-19 treatments.
The findings come from a research team at the University of Illinois Chicago team, led by Asrar Malik and Jalees Rehman, working in close collaboration with their colleagues at the University of Illinois Urbana-Champaign. The researchers had been intrigued by an earlier clinical trial testing the ACE2 decoy strategy . However, in this earlier attempt, the clinical trial found no reduction in mortality. The ACE2 drug candidate, which is soluble and degrades in the body, also proved ineffective in neutralizing the virus.
Rather than give up on the idea, the UIC team decided to give it a try. They engineered a new soluble version of ACE2 that structurally might work better as a decoy than the original one. Their version of ACE2, which includes three changes in the protein’s amino acid building blocks, binds the SARS-CoV-2 spike protein much more tightly. In the lab, it also appeared to neutralize the virus as well as monoclonal antibodies used to treat COVID-19.
To put it to the test, they conducted studies in mice. Normal mice don’t get sick from SARS-CoV-2 because the viral spike can’t bind well to the mouse version of the ACE2 receptor. So, the researchers did their studies in a mouse that carries the human ACE2 and develops a severe acute respiratory syndrome somewhat similar to that seen in humans with severe COVID-19.
In their studies, using both the original viral isolate from Washington State and the Gamma variant (P.1) first detected in Brazil, they found that infected mice infused with their therapeutic ACE2 protein had much lower mortality and showed few signs of severe acute respiratory syndrome. While the protein worked against both versions of the virus, infection with the more aggressive Gamma variant required earlier treatment. The treated mice also regained their appetite and weight, suggesting that they were making a recovery.
Further studies showed that the decoy bound to spike proteins from every variant tested, including Alpha, Beta, Delta and Epsilon. (Omicron wasn’t yet available at the time of the study.) In fact, the decoy bound just as well, if not better, to new variants compared to the original virus.
The researchers will continue their preclinical work. If all goes well, they hope to move their ACE2 decoy into a clinical trial. What’s especially promising about this approach is it could be used in combination with treatments that work in other ways, such as by preventing virus that’s already infected cells from growing or limiting an excessive and damaging immune response to the infection.
Last week, more than 17,500 people in the United States were hospitalized with severe COVID-19. We’ve got to continue to do all we can to save lives, and it will take lots of innovative ideas, like this ACE2 decoy, to put us in a better position to beat this virus once and for all.
 Engineered ACE2 decoy mitigates lung injury and death induced by SARS-CoV-2 variants.
Zhang L, Dutta S, Xiong S, Chan M, Chan KK, Fan TM, Bailey KL, Lindeblad M, Cooper LM, Rong L, Gugliuzza AF, Shukla D, Procko E, Rehman J, Malik AB. Nat Chem Biol. 2022 Jan 19.
 Recombinant human angiotensin-converting enzyme 2 (rhACE2) as a treatment for patients with COVID-19 (APN01-COVID-19). ClinicalTrials.gov.
COVID-19 Research (NIH)
Accelerating COVID-19 Therapeutic Interventions and Vaccines (NIH)
Asrar Malik (University of Illinois Chicago)
Jalees Rehman (University of Illinois Chicago)
NIH Support: National Heart, Lung, and Blood Institute; National Institute of Allergy and Infectious Diseases
Could CRISPR Gene-Editing Technology Be an Answer to Chronic Pain?
Posted on by Dr. Francis Collins
Gene editing has shown great promise as a non-heritable way to treat a wide range of conditions, including many genetic diseases and more recently, even COVID-19. But could a version of the CRISPR gene-editing tool also help deliver long-lasting pain relief without the risk of addiction associated with prescription opioid drugs?
In work recently published in the journal Science Translational Medicine, researchers demonstrated in mice that a modified version of the CRISPR system can be used to “turn off” a gene in critical neurons to block the transmission of pain signals . While much more study is needed and the approach is still far from being tested in people, the findings suggest that this new CRISPR-based strategy could form the basis for a whole new way to manage chronic pain.
This novel approach to treating chronic pain occurred to Ana Moreno, the study’s first author, when she was a Ph.D. student in the NIH-supported lab of Prashant Mali, University of California, San Diego. Mali had been studying a wide range of novel gene- and cell-based therapeutics. While reading up on both, Moreno landed on a paper about a mutation in a gene that encodes a pain-enhancing protein in spinal neurons called NaV1.7.
Moreno read that kids born with a loss-of-function mutation in this gene have a rare condition known as congenital insensitivity to pain (CIP). They literally don’t sense and respond to pain. Although these children often fail to recognize serious injuries because of the absence of pain to alert them, they have no other noticeable physical effects of the condition.
For Moreno, something clicked. What if it were possible to engineer a new kind of treatment—one designed to turn this gene down or fully off and stop people from feeling chronic pain?
Moreno also had an idea about how to do it. She’d been working on repressing or “turning off” genes using a version of CRISPR known as “dead” Cas9 . In CRISPR systems designed to edit DNA, the Cas9 enzyme is often likened to a pair of scissors. Its job is to cut DNA in just the right spot with the help of an RNA guide. However, CRISPR-dead Cas9 no longer has any ability to cut DNA. It simply sticks to its gene target and blocks its expression. Another advantage is that the system won’t lead to any permanent DNA changes, since any treatment based on CRISPR-dead Cas9 might be safely reversed.
After establishing that the technique worked in cells, Moreno and colleagues moved to studies of laboratory mice. They injected viral vectors carrying the CRISPR treatment into mice with different types of chronic pain, including inflammatory and chemotherapy-induced pain.
Moreno and colleagues determined that all the mice showed evidence of durable pain relief. Remarkably, the treatment also lasted for three months or more and, importantly, without any signs of side effects. The researchers are also exploring another approach to do the same thing using a different set of editing tools called zinc finger nucleases (ZFNs).
The researchers say that one of these approaches might one day work for people with a large number of chronic pain conditions that involve transmission of the pain signal through NaV1.7. That includes diabetic polyneuropathy, sciatica, and osteoarthritis. It also could provide relief for patients undergoing chemotherapy, along with those suffering from many other conditions. Moreno and Mali have co-founded the spinoff company Navega Therapeutics, San Diego, CA, to work on the preclinical steps necessary to help move their approach closer to the clinic.
Chronic pain is a devastating public health problem. While opioids are effective for acute pain, they can do more harm than good for many chronic pain conditions, and they are responsible for a nationwide crisis of addiction and drug overdose deaths . We cannot solve any of these problems without finding new ways to treat chronic pain. As we look to the future, it’s hopeful that innovative new therapeutics such as this gene-editing system could one day help to bring much needed relief.
 Long-lasting analgesia via targeted in situ repression of NaV1.7 in mice. Moreno AM, Alemán F, Catroli GF, Hunt M, Hu M, Dailamy A, Pla A, Woller SA, Palmer N, Parekh U, McDonald D, Roberts AJ, Goodwill V, Dryden I, Hevner RF, Delay L, Gonçalves Dos Santos G, Yaksh TL, Mali P. Sci Transl Med. 2021 Mar 10;13(584):eaay9056.
 Nuclease dead Cas9 is a programmable roadblock for DNA replication. Whinn KS, Kaur G, Lewis JS, Schauer GD, Mueller SH, Jergic S, Maynard H, Gan ZY, Naganbabu M, Bruchez MP, O’Donnell ME, Dixon NE, van Oijen AM, Ghodke H. Sci Rep. 2019 Sep 16;9(1):13292.
 Drug Overdose Deaths. Centers for Disease Control and Prevention.
Congenital insensitivity to pain (National Center for Advancing Translational Sciences/NIH)
Opioids (National Institute on Drug Abuse/NIH)
Mali Lab (University of California, San Diego)
Navega Therapeutics (San Diego, CA)
NIH Support: National Human Genome Research Institute; National Cancer Institute; National Institute of General Medical Sciences; National Institute of Neurological Disorders and Stroke
Nanoparticle Technology Holds Promise for Protecting Against Many Coronavirus Strains at Once
Posted on by Dr. Francis Collins
It’s truly encouraging to witness people all across our nation rolling up their sleeves to get their COVID-19 vaccines. That is our best chance to end this pandemic. But this is the third coronavirus to emerge and cause serious human illness in the last 20 years, and it’s probably not the last. So, this is also an opportunity to step up our efforts to develop vaccines to combat future strains of disease-causing coronavirus. With this in mind, I’m heartened by a new NIH-funded study showing the potential of a remarkably adaptable, nanoparticle-based approach to coronavirus vaccine development .
Both COVID-19 vaccines currently authorized for human use by the Food and Drug Administration (FDA) work by using mRNA to instruct our cells to make an essential portion of the spike protein of SARS-CoV-2, which is the novel coronavirus that causes COVID-19. As our immune system learns to recognize this protein fragment as foreign, it produces antibodies to attack SARS-CoV-2 and prevent COVID-19. What makes the new vaccine technology so powerful is that it raises the possibility of training the immune system to recognize not just one strain of coronavirus—but up to eight—with a single shot.
This approach has not yet been tested in people, but when a research team, led by Pamela Bjorkman, California Institute of Technology, Pasadena, injected this new type of vaccine into mice, it spurred the production of antibodies that react to a variety of different coronaviruses. In fact, some of the mouse antibodies proved to be reactive to related strains of coronavirus that weren’t even represented in the vaccine. These findings suggest that if presented with multiple different fragments of the spike protein’s receptor binding domain (RBD), which is what SARS-like coronaviruses use to infect human cells, the immune system may learn to recognize common features that might protect against as-yet unknown, newly emerging coronaviruses.
This new work, published in the journal Science, utilizes a technology called a mosaic nanoparticle vaccine platform . Originally developed by collaborators at the University of Oxford, United Kingdom, the nanoparticle component of the platform is a “cage” made up of 60 identical proteins. Each of those proteins has a small protein tag that functions much like a piece of Velcro®. In their SARS-CoV-2 work, Bjorkman and her colleagues, including graduate student Alex A. Cohen, engineered multiple different fragments of the spike protein so each had its own Velcro-like tag. When mixed with the nanoparticle, the spike protein fragments stuck to the cage, resulting in a vaccine nanoparticle with spikes representing four to eight distinct coronavirus strains on its surface. In this instance, the researchers chose spike protein fragments from several different strains of SARS-CoV-2, as well as from other related bat coronaviruses thought to pose a threat to humans.
The researchers then injected the vaccine nanoparticles into mice and the results were encouraging. After inoculation, the mice began producing antibodies that could neutralize many different strains of coronavirus. In fact, while more study is needed to understand the mechanisms, the antibodies responded to coronavirus strains that weren’t even represented on the mosaic nanoparticle. Importantly, this broad antibody response came without apparent loss in the antibodies’ ability to respond to any one particular coronavirus strain.
The findings raise the exciting possibility that this new vaccine technology could provide protection against many coronavirus strains with a single shot. Of course, far more study is needed to explore how well such vaccines work to protect animals against infection, and whether they will prove to be safe and effective in people. There will also be significant challenges in scaling up manufacturing. Our goal is not to replace the mRNA COVID-19 vaccines that scientists developed at such a remarkable pace over the last year, but to provide much-needed vaccine strategies and tools to respond swiftly to the emerging coronavirus strains of the future.
As we double down on efforts to combat COVID-19, we must also come to grips with the fact that SARS-CoV-2 isn’t the first—and surely won’t be the last—novel coronavirus to cause disease in humans. With continued research and development of new technologies such as this one, the hope is that we will come out of this terrible pandemic better prepared for future infectious disease threats.
 Mosaic RBD nanoparticles elicit neutralizing antibodies against SARS-CoV-2 and zoonotic coronaviruses. Cohen AA, Gnanapragasam PNP, Lee YE, Hoffman PR, Ou S, Kakutani LM, Keeffe JR, Barnes CO, Nussenzweig MC, Bjorkman PJ. Science. 2021 Jan 12.
COVID-19 Research (NIH)
Bjorkman Lab (California Institute of Technology, Pasadena)
NIH Support: National Institute of Allergy and Infectious Diseases