COVID-19 Vaccine: Washington University’s Genetically Modified Virus Based Vaccine Shows Promise In Mice And Prevents Severe Disease Progression
Source: COVID-19 Vaccine Aug 13, 2020 4 years, 3 months, 1 week, 3 days, 21 minutes ago
COVID-19 Vaccine: A new vaccine made from a mild virus genetically modified to carry a key gene from the SARS-CoV-2 coronavirus is effective at preventing pneumonia in mice infected with the COVID-19 virus, according to research findings from Washington University School of Medicine in St. Louis.
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Co-senior author Dr Michael S. Diamond, MD, PhD, the Herbert S. Gasser Professor of Medicine and a Professor of molecular microbiology, and of pathology and immunology told Thailand Medical News, “Unlike many of the other vaccines under development, this vaccine is made from a virus that is capable of spreading in a controlled manner inside the human body, which means it is likely to generate a strong immune response.”
He further added, “Since the virus is capable of replicating, it can be grown to high levels in the lab, so it’s easy to scale up and should be more cost-effective than some of the other vaccine candidates. So while what we have shown is just the proof of concept, I think it’s very promising. Our vaccine candidate is now being tested in additional animal models with the goal of getting it into clinical trials as soon as possible.”
The research development and research findings or the vaccine are published in the journal: Cell Host and Microbe.
https://www.sciencedirect.com/science/article/pii/S1931312820304212?via%3Dihub
Dr Diamond and colleagues including co-senior author Dr Sean Whelan, PhD, the Marvin A. Brennecke Distinguished Professor and head of the Department of Molecular Microbiology; and co-first authors Dr Brett Case, PhD, a postdoctoral researcher in Diamond’s laboratory, and Dr Paul W. Rothlauf, a graduate student in Whelan’s laboratory created the experimental vaccine by genetically modifying vesicular stomatitis virus (VSV), a virus of livestock that causes only a mild, short-lived illness in people.
The researchers swapped out one gene from the vesicular stomatitis virus (VSV ) for the gene from the spike from SARS-CoV-2, the virus that causes COVID-19.
The new hybrid virus is called VSV-SARS-CoV-2.
The Spike protein is thought to be one of the keys to immunity against COVID-19. The COVID-19 virus uses spike to latch onto and infect human cells, and the human body defends itself by generating protective antibodies targeting spike.
Simply by incorporating the gene for spike to a fairly harmless virus, the researchers created a hybrid virus that, when given to individuals, ideally would elicit antibodies against spike that protect against later infection with the COVID-19 virus.
It should be noted that the same strategy was used to design the Ebola vaccine that was approved by the U.S. FDA in 2019. That vaccine which is made from VSV genetically modified with a gene from Ebola virus.
To date that vaccine has been safely administered to thousands of people in Africa, Europe and North America, and helped end the 2018 to 2020 Ebola outbreak in the Democratic Republic of the Congo.
The researchers also inj
ected mice with VSV-SARS-CoV-2 or a lab strain of VSV for comparison. A subgroup was boosted with a second dose of the experimental vaccine four weeks after the initial injections. Three weeks after each injection, the researchers drew blood from the mice to test for antibodies capable of preventing SARS-CoV-2 from infecting cells. They found high levels of such neutralizing antibodies after one dose, and the levels increased 90-fold after a second dose.
Importantly, the researchers challenged the mice five weeks after their last dose by spraying the COVID-19 virus into their noses. The vaccine completely protected against pneumonia. At four days post infection, there was no infectious virus detectable in the lungs of mice that had been given either one or two doses of the vaccine. In contrast, mice that had received the placebo had high levels of virus in their lungs. In addition, the lungs of vaccinated mice showed fewer signs of inflammation and damage than those of mice that had received the placebo.
The newly created vaccine is still in the early stages of development.
Since mice do not naturally become infected with the COVID-19 virus, in order to assess whether the vaccine elicited a protective immune response in them, the researchers used genetically modified mice or, in unmodified mice, employed a complicated technique to induce susceptibility to infection.
The study team are in the process of repeating the experiments in other animal models that are naturally susceptible to the COVID-19 virus. If the vaccine also protects those animals from COVID-19, the next step would be to scale up production under what the Food and Drug Administration refers to as “good manufacturing practice (GMP) conditions” and launch a clinical trial in humans.
Although the data are promising, this vaccine is still months behind in the race to develop a pandemic-ending vaccine.
To date, six vaccines are in the final stage of testing in humans, and Dr Anthony Fauci, MD, director of the U.S. National Institute of Allergy and Infectious Diseases, has said he expects a vaccine to be ready for mass distribution early next year.
D Whelan added, “It is really going to depend on how successful the first vaccines that come out for COVID are. If they do not produce a robust, durable immune response or there are safety issues, there might be the opportunity for a second-generation vaccine that could induce sterilizing immunity and interrupt the cycle of transmission.”
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