Tag Archives: SARS-CoV-2
A team of scientists is calling for greater research into how sunlight inactivates SARS-CoV-2 after realizing there’s a glaring discrepancy between the most recent theory and experimental results. UC Santa Barbara mechanical engineer Paolo Luzzatto-Fegiz and colleagues noticed the virus was inactivated as much as eight times faster in experiments than the most recent theoretical model predicted.
“The theory assumes that inactivation works by having UVB hit the RNA of the virus, damaging it,” explained Luzzatto-Fegiz.
But the discrepancy suggests there’s something more going on than that, and figuring out what this is may be helpful for managing the virus.
UV light, or the ultraviolet part of the spectrum, is easily absorbed by certain nucleic acid bases in DNA and RNA, which can cause them to bond in ways that are hard to fix.
But not all UV light is the same. Longer UV waves, called UVA, don’t have quite enough energy to cause problems. It’s the mid-range UVB waves in sunlight that are primarily responsible for killing microbes and putting our own cells at risk of Sun damage.
But this type of UV doesn’t usually come into contact with Earth’s surface, thanks to the ozone layer.
“UVC is great for hospitals,” said co-author and Oregon State University toxicologist Julie McMurry. “But in other environments – for instance, kitchens or subways – UVC would interact with the particulates to produce harmful ozone.”
In July 2020, an experimental study tested the effects of UV light on SARS-CoV-2 in simulated saliva. They recorded the virus was inactivated when exposed to simulated sunlight for between 10-20 minutes.
“Natural sunlight may be effective as a disinfectant for contaminated nonporous materials,” Wood and colleagues concluded in the paper.
Luzzatto-Feigiz and team compared those results with a theory about how sunlight achieved this, which was published just a month later, and saw the math didn’t add up. his study found the SARS-CoV-2 virus was three times more sensitive to the UV in sunlight than influenza A, with 90 percent of the coronavirus‘s particles being inactivated after just half an hour of exposure to midday sunlight in summer.
By comparison, in winter light infectious particles could remain intact for days.
Researchers from Cleveland Clinic’s Global Center for Pathogen Research & Human Health have developed a promising new COVID-19 vaccine candidate that utilizes nanotechnology and has shown strong efficacy in preclinical disease models.
According to new findings published in mBio, the vaccine produced potent neutralizing antibodies among preclinical models and also prevented infection and disease symptoms in the face of exposure to SARS-CoV-2 (the virus that causes COVID-19). An additional reason for the vaccine candidate’s early appeal is that it may be thermostable, which would make it easier to transport and store than currently authorized COVID-19 vaccines.
“Our vaccine candidate delivers antigens to trigger an immune response via nanoparticles engineered from ferritin–a protein found in almost all living organisms,” said Jae Jung, PhD, director of the Global Center for Human Health & Pathogen Research and co-senior author on the study. “This protein is an attractive biomaterial for vaccine and drug delivery for many reasons, including that it does not require strict temperature control.”
Added Dokyun (Leo) Kim, a graduate student in Dr. Jung’s lab and co-first author on the study, “This would dramatically ease shipping and storage constraints, which are challenges we’re currently experiencing in national distribution efforts. It would also be beneficial for distribution to developing countries.”
Other benefits of the protein nanoparticles include minimizing cellular damage and providing stronger immunity at lower doses than traditional protein subunit vaccines against other viruses, like influenza.
The team’s vaccine uses the ferritin nanoparticles to deliver tiny, weakened fragments from the region of the SARS-CoV-2 spike protein that selectively binds to the human entry point for the virus (this fragment is called the receptor-binding domain, or RBD). When the SARS-CoV-2 RBD binds with the human protein called ACE2 (angiotensin-converting enzyme 2), the virus can enter host cells and begin to replicate.
The researchers tested their vaccine candidate on a ferret model of COVID-19, which reflects the human immune response and disease development better than other preclinical models. Dr. Jung, a foremost authority in virology and virus-induced cancers, previously developed the world’s first COVID-19 ferret model–a discovery that has significantly advanced research into SARS-CoV-2 infection and transmission.
Scientists in the UK have just recruited the first participants in the world to be part of a new long-acting antibody study. If the treatment is effective, it could give those who have already been exposed to SARS-CoV-2 protection from developing COVID-19.
“We know that this antibody combination can neutralise the virus,” explains University College London Hospitals (UCLH) virologist Catherine Houlihan. “So we hope to find that giving this treatment via injection can lead to immediate protection against the development of COVID-19 in people who have been exposed – when it would be too late to offer a vaccine.”
This might not be the first antibody treatment for COVID-19 you’ve heard of. Outgoing US President Donald Trump was given monoclonal antibodies when he came down with the disease, and in the US two different antibody treatments – casirivimab and imdevimab – received emergency approval back in November. But those antibody treatments are given to patients with mild or moderate COVID-19, who risk progressing to a severe version of the disease.
“In a clinical trial of patients with COVID-19, casirivimab and imdevimab, administered together, were shown to reduce COVID-19-related hospitalisation or emergency room visits in patients at high risk for disease progression within 28 days after treatment when compared to placebo,” the FDA explained in a press statement when the drugs were approved. This new antibody therapy, called AZD7442 and developed by UCLH and AstraZeneca, is a little different. AZD7442 is a combination of two monoclonal antibodies AZD8895 and AZD1061, which both target the receptor binding domain of the SARS-CoV-2 spike protein.
“By targeting this region of the virus’s spike protein, antibodies can block the virus’s attachment to human cells, and, therefore, is expected to block infection,” the team wrote on the US ClinicalTrials.gov website. “Amino acid substitutions have been introduced into the antibodies to both extend their half-lives, which should prolong their potential prophylactic benefit, and decrease Fc effector functionin order to decrease the potential risk of antibody-dependent enhancement of disease.”
Antibodies are little Y-shaped proteins that lock on to a particular section – called an antigen – of a virus, bacterium or other pathogen, and either ‘tag‘ it to be attacked by the immune system, or directly block the pathogen from invading our cells. Normal antibodies are produced by your body after an infection, while monoclonal antibodies are cloned in a lab and can be injected into a person already infected, to give the immune system a hand in the fight.
The researchers are hoping that AZD7442 – which is just starting the Storm Chaser study (the name for its phase 3 trial) – provides protection for those that have been exposed to the virus but do not yet have symptoms. Effectively, they’re trying to stop COVID-19 happening in the first place. “If you are dealing with outbreaks in settings such as care homes, or if you have got patients who are particularly at risk of getting severe COVID, such as the elderly, then this could well save a lot of lives,” said University of East Anglia infectious disease expert Paul Hunter.
As the COVID-19 pandemic continues to spread across the world, testing remains a key strategy for tracking and containing the virus. Bioengineering graduate student, Maha Alafeef, has co-developed a rapid, ultrasensitive test using a paper-based electrochemical sensor that can detect the presence of the virus in less than five minutes. The team led by professor Dipanjan Pan reported their findings in ACS Nano.
“Currently, we are experiencing a once-in-a-century life-changing event,” said Alafeef. “We are responding to this global need from a holistic approach by developing multidisciplinary tools for early detection and diagnosis and treatment for SARS-CoV-2.”
There are two broad categories of COVID-19 tests on the market. The first category uses reverse transcriptase real-time polymerase chain reaction (RT-PCR) and nucleic acid hybridization strategies to identify viral RNA. Current FDA-approved diagnostic tests use this technique. Some drawbacks include the amount of time it takes to complete the test, the need for specialized personnel and the availability of equipment and reagents. The second category of tests focuses on the detection of antibodies. However, there could be a delay of a few days to a few weeks after a person has been exposed to the virus for them to produce detectable antibodies.
n recent years, researchers have had some success with creating point-of-care biosensors using 2D nanomaterials such as graphene to detect diseases. The main advantages of graphene-based biosensors are their sensitivity, low cost of production and rapid detection turnaround. “The discovery of graphene opened up a new era of sensor development due to its properties. Graphene exhibits unique mechanical and electrochemical properties that make it ideal for the development of sensitive electrochemical sensors,” said Alafeef. The team created a graphene-based electrochemical biosensor with an electrical read-out setup to selectively detect the presence of SARS-CoV-2 genetic material.
There are two components to this biosensor: a platform to measure an electrical read-out and probes to detect the presence of viral RNA. To create the platform, researchers first coated filter paper with a layer of graphene nanoplatelets to create a conductive film. Then, they placed a gold electrode with a predefined design on top of the graphene as a contact pad for electrical readout. Both gold and graphene have high sensitivity and conductivity which makes this platform ultrasensitive to detect changes in electrical signals.
Pfizer Inc. (NYSE: PFE) and BioNTech SE (Nasdaq: BNTX) today announced their mRNA-based vaccine candidate, BNT162b2, against SARS-CoV-2 has demonstrated evidence of efficacy against COVID-19 in participants without prior evidence of SARS-CoV-2 infection, based on the first interim efficacy analysis conducted on November 8, 2020 by an external, independent Data Monitoring Committee (DMC) from the Phase 3 clinical study.
After discussion with the Food and Drug Administration (FDA), the companies recently elected to drop the 32-case interim analysis and conduct the first interim analysis at a minimum of 62 cases. Upon the conclusion of those discussions, the evaluable case count reached 94 and the DMC performed its first analysis on all cases. The case split between vaccinated individuals and those who received the placebo indicates a vaccine efficacy rate above 90%, at 7 days after thed second dose. This means that protection is achieved 28 days after the initiation of the vaccination, which consists of a 2-dose schedule. As the study continues, the final vaccine efficacy percentage may vary. The DMC has not reported any serious safety concerns.
“Today is a great day for science and humanity. The first set of results from our Phase 3 COVID-19 vaccine trial provides the initial evidence of our vaccine’s ability to prevent COVID-19,” said Dr. Albert Bourla, Pfizer Chairman and CEO. “We are reaching this critical milestone in our vaccine development program at a time when the world needs it most with infection rates setting new records, hospitals nearing over-capacity and economies struggling to reopen. With today’s news, we are a significant step closer to providing people around the world with a much-needed breakthrough to help bring an end to this global health crisis. We look forward to sharing additional efficacy and safety data generated from thousands of participants in the coming weeks.”