Posted on by Dr. Francis Collins
These round, multi-colored orbs in the illustration above may resemble SARS-CoV-2, the coronavirus responsible for COVID-19. But they’re actually lab-made nanocrystals called quantum dots. They have been specially engineered to look and, in some ways, act like the coronavirus while helping to solve a real challenge for many labs that would like to study SARS-CoV-2.
Quantum dots, which have been around since the mid-1980s, are designed with special optical properties that allow them to fluoresce when exposed to ultraviolet light. The two pictured here are about 10 nanometers in diameter, about 3,000 times smaller than the width of a human hair. The quantum dot consists of a semi-conductive cadmium selenide inner core (orange) surrounded by a zinc sulfide outer shell (teal). Molecules on its surface (yellow) allow researchers to attach the viral spike protein (purple), which SARS-CoV-2 depends on to infect human cells.
To the left is a human cell (gray) studded with the ACE2 receptors (blue) that those viral spike proteins bind to before SARS-CoV-2 enters and infects our cells. In the background, you see another spike protein-studded quantum dot. But human neutralizing antibodies (pink) are preventing that one from reaching the human cell.
Because SARS-CoV-2 is so highly infectious, basic researchers without access to specially designed biosafety facilities may be limited in their ability to study the virus. But these harmless quantum dots offer a safe workaround. While the quantum dots may bind and enter human cells just like the virus, they can’t cause an infection. They offer a quick, informative way to assess the potential of antibodies or other compounds to prevent the coronavirus from binding to our cells.
In work published in the journal ACS Nano, a team that included Kirill Gorshkov, NIH’s National Center for Advancing Translational Sciences (NCATS), Rockville, MD, along with Eunkeu Oh and Mason Wolak, Naval Research Laboratory, Washington, D.C., demonstrated how these quantum dots may serve as a useful new tool to speed the search for new COVID-19 treatments. The dots’ fluorescent glow enabled the researchers to use a microscope to observe how these viral mimics bind to ACE2 in real time, showing how SARS-CoV-2 might attach to and enter our cells, and suggesting ways to intervene.
Indeed, imagine thousands of tiny wells in which human cells are growing. Imagine adding a different candidate drug to each well; then imagine adding the loaded quantum dots to each well and using machine vision to identify the wells where the dots could not enter the cell. That’s not science fiction. That’s now.
With slightly different versions of their quantum dots, the NCATS researchers and their colleagues at the Naval Research Laboratory will now explore how other viral proteins are important for the coronavirus to infect our cells. They also can test how slight variations in the spike protein may influence SARS-CoV-2’s behavior. This work provides yet another stunning example of how scientists with widely varying expertise have banded together—using all the tools at their disposal—to forge ahead to find solutions to COVID-19.
 Quantum dot-conjugated SARS-CoV-2 spike pseudo-virions enable tracking of angiotensin converting enzyme 2 binding and endocytosis. Gorshkov K, Susumu K, Chen J, Xu M, Pradhan M, Zhu W, Hu X, Breger JC, Wolak M, Oh E. ACS Nano. 2020 Sep 22;14(9):12234-12247.
What are Quantum Dots? (National Institute of Biomedical Imaging and Bioengineering/NIH)
Coronavirus (COVID-19) (NIH)
I Am Translational Science: Kirill Gorshkov (National Center for Advancing Translational Sciences/NIH)
U. S. Naval Research Laboratory (Washington, D.C.)
NIH Support: National Center for Advancing Translational Sciences
Posted on by Dr. Francis Collins
Most children infected with SARS-CoV-2, the virus that causes COVID-19, develop only a mild illness. But, days or weeks later, a small percentage of kids go on to develop a puzzling syndrome known as multisystem inflammatory syndrome in children (MIS-C). This severe inflammation of organs and tissues can affect the heart, lungs, kidneys, brain, skin, and eyes.
Thankfully, most kids with MIS-C respond to treatment and make rapid recoveries. But, tragically, MIS-C can sometimes be fatal.
With COVID-19 cases in children having increased by 21 percent in the United States since early August , NIH and others are continuing to work hard on getting a handle on this poorly understood complication. Many think that MIS-C isn’t a direct result of the virus, but seems more likely to be due to an intense autoimmune response. Indeed, a recent study in Nature Medicine  offers some of the first evidence that MIS-C is connected to specific changes in the immune system that, for reasons that remain mysterious, sometimes follow COVID-19.
These findings come from Shane Tibby, a researcher at Evelina London Children’s Hospital, London. United Kingdom; Manu Shankar-Hari, a scientist at Guy’s and St Thomas’ NHS Foundation Trust, London; and colleagues. The researchers enlisted 25 children, ages 7 to 14, who developed MIS-C in connection with COVID-19. In search of clues, they examined blood samples collected from the children during different stages of their care, starting when they were most ill through recovery and follow-up. They then compared the samples to those of healthy children of the same ages.
What they found was a complex array of immune disruptions. The children had increased levels of various inflammatory molecules known as cytokines, alongside raised levels of other markers suggesting tissue damage—such as troponin, which indicates heart muscle injury.
The neutrophils, monocytes, and other white blood cells that rapidly respond to infections were activated as expected. But the levels of certain white blood cells called T lymphocytes were paradoxically reduced. Interestingly, despite the low overall numbers of T lymphocytes, particular subsets of them appeared activated as though fighting an infection. While the children recovered, those differences gradually disappeared as the immune system returned to normal.
It has been noted that MIS-C bears some resemblance to an inflammatory condition known as Kawasaki disease, which also primarily affects children. While there are similarities, this new work shows that MIS-C is a distinct illness associated with COVID-19. In fact, only two children in the study met the full criteria for Kawasaki disease based on the clinical features and symptoms of their illness.
Another recent study from the United Kingdom, reported several new symptoms of MIS-C . They include headaches, tiredness, muscle aches, and sore throat. Researchers also determined that the number of platelets was much lower in the blood of children with MIS-C than in those without the condition. They proposed that evaluating a child’s symptoms along with his or her platelet level could help to diagnose MIS-C.
It will now be important to learn much more about the precise mechanisms underlying these observed changes in the immune system and how best to treat or prevent them. In support of this effort, NIH recently announced $20 million in research funding dedicated to the development of approaches that identify children at high risk for developing MIS-C .
The hope is that this new NIH effort, along with other continued efforts around the world, will elucidate the factors influencing the likelihood that a child with COVID-19 will develop MIS-C. Such insights are essential to allow doctors to intervene as early as possible and improve outcomes for this potentially serious condition.
 Peripheral immunophenotypes in children with multisystem inflammatory syndrome associated with SARS-CoV-2 infection. Carter MJ, Fish M, Jennings A, Doores KJ, Wellman P, Seow J, Acors S, Graham C, Timms E, Kenny J, Neil S, Malim MH, Tibby SM, Shankar-Hari M. Nat Med. 2020 Aug 18.
 Children and COVID-19: State-Level Data Report. American Academy of Pediatrics. August 24, 2020.
 Clinical characteristics of children and young people admitted to hospital with covid-19 in United Kingdom: prospective multicentre observational cohort study. Swann OV, Holden KA, Turtle L, Harrison EW, Docherty AB, Semple MG, et al. Br Med J. 2020 Aug 17.
 NIH-funded project seeks to identify children at risk for MIS-C. NIH. August 7, 2020.
Coronavirus (COVID-19) (NIH)
Kawasaki Disease (Genetic and Rare Disease Information Center/National Center for Advancing Translational Sciences/NIH)
Shane Tibby (Evelina London Children’s Hospital, London)
Manu Shankar-Hari (King’s College, London)
NIH Support: Eunice Kennedy Shriver National Institute of Child Health and Human Development; Office of the Director; National Heart, Lung, and Blood Institute; National Institute of Allergy and Infectious Diseases; National Institute of Arthritis and Musculoskeletal and Skin Diseases; National Institute on Drug Abuse; National Institute of Minority Health and Health Disparities; Fogarty International Center
Posted on by Dr. Francis Collins
It usually takes more than a decade to develop a safe, effective anti-viral therapy. But, when it comes to coronavirus disease 2019 (COVID-19), we don’t have that kind of time. One way to speed the process may be to put some old drugs to work against this new disease threat. This is generally referred to as “drug repurposing.”
NIH has been doing everything possible to encourage screens of existing drugs that have been shown safe for human use. In a recent NIH-funded study in the journal Nature, researchers screened a chemical “library” that contained nearly 12,000 existing drug compounds for their potential activity against SARS-CoV-2, the novel coronavirus that causes COVID-19 . The results? In tests in both non-human primate and human cell lines grown in laboratory conditions, 21 of these existing drugs showed potential for repurposing to thwart the novel coronavirus—13 of them at doses that likely could be safely given to people. The majority of these drugs have been tested in clinical trials for use in HIV, autoimmune diseases, osteoporosis, and other conditions.
These latest findings come from an international team led by Sumit Chanda, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA. The researchers took advantage of a small-molecule drug library called ReFRAME , which was created in 2018 by Calibr, a non-profit drug discovery division of Scripps Research, La Jolla, CA.
In collaboration with Yuen Kwok-Yung’s team at the University of Hong Kong, the researchers first developed a high-throughput method that enabled them to screen rapidly each of the 11,987 drug compounds in the ReFRAME library for their potential to block SARS-CoV-2 in cells grown in the lab. The first round of testing narrowed the list of possible COVID-19 drugs to about 300. Next, using lower concentrations of the drugs in cells exposed to a second strain of SARS-CoV-2, they further narrowed the list to 100 compounds that could reliably limit growth of the coronavirus by at least 40 percent.
Generally speaking, an effective anti-viral drug is expected to show greater activity as its concentration is increased. So, Chanda’s team then tested those 100 drugs for evidence of such a dose-response relationship. Twenty-one of them passed this test. This group included remdesivir, a drug originally developed for Ebola virus disease and recently authorized by the U.S. Food and Drug Administration (FDA) for emergency use in the treatment of COVID-19. Remdesivir could now be considered a positive control.
These findings raised another intriguing question: Could any of the other drugs with a dose-response relationship work well in combination with remdesivir to block SARS-CoV-2 infection? Indeed, the researchers found that four of them could.
Further study showed that some of the most promising drugs on the list reduced the number of SARS-CoV-2 infected cells by 65 to 85 percent. The most potent of these was apilimod, a drug that has been evaluated in clinical trials for treating Crohn’s disease, rheumatoid arthritis, and other autoimmune conditions. Apilimod is now being evaluated in the clinic for its ability to prevent the progression of COVID-19. Another potential antiviral to emerge from the study is clofazimine, a 70-year old FDA-approved drug that is on the World Health Organization’s list of essential medicines for the treatment of leprosy.
Overall, the findings suggest that there may be quite a few existing drugs and/or experimental drugs fairly far along in the development pipeline that have potential to be repurposed for treating COVID-19. What’s more, some of them might also work well in combination with remdesivir, or perhaps other drugs, as treatment “cocktails,” such as those used to successfully treat HIV and hepatitis C.
This is just one of a wide variety of drug screening efforts that are underway, using different libraries and different assays to detect activity against SARS-CoV-2. The NIH’s National Center for Advancing Translational Sciences has established an open data portal to collect all of these data as quickly and openly as possible. As NIH continues its efforts to use the power of science to end the COVID-19 pandemic, it is critically important that we explore as many avenues as possible for developing diagnostics, treatments, and vaccines.
 Discovery of SARS-CoV-2 antiviral drugs through large-scale compound repurposing. Riva L, Yuan S, Yin X, et al. Nature. 2020 Jul 24 [published online ahead of print]
 The ReFRAME library as a comprehensive drug repurposing library and its application to the treatment of cryptosporidiosis. Janes J, Young ME, Chen E, et al. Proc Natl Acad Sci USA. 2018;115(42):10750-10755.
Coronavirus (COVID-19) (NIH)
ReFRAMEdb (Scripps Research, La Jolla, CA)
The Chanda Lab (Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA)
Yuen Kwok-Yung (University of Hong Kong)
OpenData|Covid-19 (National Center for Advancing Translational Sciences/NIH)
NIH Support: National Institute of Allergy and Infectious Diseases; National Institute of General Medical Sciences