Experimental COVID-19 vaccine prevents severe illness in mice

Experimental vaccines are effective in preventing pneumonia in mice infected with the COVID-19 virus, according to a study by the Washington University School of Medicine in St. Louis. The vaccine is made from a mild virus that has been genetically modified to carry a key gene in the COVID-19 virus and is listed in the journal Cell host and microorganism..

“Unlike many other vaccines in development, this vaccine is made from a virus that can spread in a limited way in the human body, which means it is likely to produce a strong immune response. Means S. Diamond, MD, Ph.D. , Professor Herbert S. Gasser, Professor of Molecular Microbiology, Pathology and Immunology. “Because the virus can replicate, it can be grown to high levels in the lab, so it should be easy to scale up and cost-effective than some others. Vaccine candidate.. So, what I have shown here is just a proof of concept, but I think it is very promising. Our vaccine candidates are currently being tested in additional animal models with the goal of entering clinical trials as soon as possible. “

Diamond and colleagues — co-author Sean Whelan, Ph.D., Marvin A. Brennecke Distinguished Professor and Dean of Molecular Microbiology. Co-author Dr. Brett Case, a post-doctoral fellow in the Diamond lab, and Paul W. Roslauf, a graduate student in the Whelan lab, genetically engineered an vaccine. Vesicular stomatitis virus (VSV), a livestock virus that causes mild, short-lived diseases in people. They replaced one gene from VSV with a spiked gene from SARS-CoV-2, the virus that causes COVID-19. The hybrid virus is called VSV-SARS-CoV-2.

Spike proteins are considered to be one of the keys to immunization against COVID-19. The COVID-19 virus uses spikes to latch and infect human cells, human body Protects itself by producing protective antibodies that target the spikes. By adding the spike gene to a fairly innocuous virus, researchers created a hybrid virus that, when given to humans, would ideally elicit antibodies against the spike that would prevent subsequent infection by the COVID-19 virus. ..

The same strategy was used to design the Ebola vaccine approved by the US Food and Drug Administration in 2019. The vaccine, made from VSV genetically engineered with the Ebola virus gene, has been safely administered to thousands of people in Africa, Ebola 2018-2020 in Europe, North America, and the Democratic Republic of the Congo. Helped end the outbreak.

As part of this research, researchers mouse Compare using VSV-SARS-CoV-2 or VSV laboratory strains. Four weeks after the first injection, a second dose of vaccine was added to the subgroup. Three weeks after each injection, researchers took blood from the mice and tested antibodies that could prevent SARS-CoV-2 from infecting the cells. They found high levels of such neutralizing antibodies after one dose, which levels increased 90-fold after the second dose.

The researchers then challenged the mice 5 weeks after the last dose by spraying the COVID-19 virus nasally. The vaccine completely prevented pneumonia. Four days after infection, no infectious virus was detected in the lungs of mice given one or two doses of the vaccine. In contrast, mice receiving placebo had high levels of virus in the lungs. Moreover, vaccinated mouse lungs showed less signs of inflammation and injury than those of placebo-treated mice.

of Experimental vaccine It is still in the early stages of development.

Because mice do not spontaneously become infected with the COVID-19 virus, we used genetically engineered mice or complicated techniques for unmodified mice to assess whether the vaccine elicited a protective immune response. Induced susceptibility to infection. Researchers are in the process of repeating experiments in other animal models that are naturally susceptible to COVID-19 Virus.. If the vaccine also protects these animals from COVID-19, the next step is to expand production under what the Food and Drug Administration calls “good manufacturing practice (GMP) conditions” and start clinical trials in people. is.

The data are promising, but the vaccine is still a few months behind in the race to develop a vaccine to end the pandemic. Six vaccines are in the final stages of trials in humans, and Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said he expects the vaccines to be ready for mass distribution early next year. ..

“It really will depend on how successful the first vaccine that comes out for COVID is,” Whelan said. “If you don’t generate a robust and durable immune response, or if you have safety issues, you might have a second generation opportunity vaccine This can induce bactericidal immunity and interfere with the cycle of infection. ”