A colored scanning electron microscope image of the SARS-CoV-2 virus. Image Credit: NIAID
Genetic analysis of sequences from more than 27,000 people infected with the coronavirus that causes COVID-19 shows the virus has been minimally mutated since December 2019, suggesting that a vaccine would be enough to fight global infections.
The study was carried out by a team of scientists from the Walter Reed Army Institute of Research led by Morgane Rolland, Head of Viral Genetics and Systems Serology for the WRAIR Military HIV Research Program, and Dr. Kayvon Modjarrad, director of the institute's Emerging Infectious Diseases Program. A manuscript detailing the results was published in Proceedings of the National Academy of Sciences.
To characterize the diversification of the SARS-CoV-2 coronavirus since the start of the pandemic, they aligned 18,514 independent virus genome sequences taken from individuals in 84 countries and scanned them for variations. Analyzes show low estimates of genetic differentiation after the first outbreak and show that the SARS-CoV-2 genome has so far evolved through a mostly random process rather than adaptation to the human hosts it encounters.
"As in other reports, we found that the frequency of the D614G mutation in the spike has increased rapidly since the epidemic began, but we have not been able to link this mutation to any specific adaptive forces," Rolland said. "When viruses multiply and spread through the population, we expect some mutations, some of which by chance can be fixed very quickly in an epidemic." Rolland noted that linking genotypes to phenotypes is complicated and further research is needed to fully understand the functional consequences of the D614G mutation in SARS-CoV-2.
Given the small amount of genetic variation, a promising vaccine candidate would likely be equally effective against all currently circulating strains of the COVID-19 coronavirus.
"Viral diversity has challenged vaccine development efforts for other viruses such as HIV, influenza and dengue. However, global samples show that SARS-CoV-2 is less diverse than these viruses," Rolland said. "We can therefore be cautiously optimistic that viral diversity should not be an obstacle to the development of a largely protective vaccine against COVID-19 infections."
Modjarrad is co-leading the institute's COVID-19 response efforts, including developing a vaccine for COVID-19. WRAIR's lead vaccine candidate is based on a spike ferritin nanoparticle platform and is expected to be used in human testing before 2021. The vaccine is combined with a proprietary adjuvant, also developed at WRAIR, the Army Liposome Formulation, to further boost the immune response.
"Scientists are working hard to accelerate the development of a COVID-19 vaccine that is safe and effective for the world now and for years to come. This data is critical to the field's collective effort to get a vaccine quickly at scale and universally applicable to all population groups, "said Modjarrad.
He added, "With WRAIR's extensive experience developing vaccines against other viruses and recent work on coronaviruses, we have been able to quickly accelerate research efforts to combat this pandemic that threatens global health and military readiness." WRAIR was founded 127 years ago to combat these types of health threats and has played a role in the development of nearly half of the vaccines in public use today.
Rolland, whose research normally focuses on the genetics of HIV viruses, has turned her attention to COVID-19 during the current global health emergency. "It is important that people in different fields come together when we focus on learning all about this virus," she said. "Teamwork will be vital to contain the tide of this pandemic." Rolland is with the Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. and has been a researcher at WRAIR since 2010.
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Bethany Dearlove et al., A SARS-CoV-2 Vaccine Candidate Would Likely Match All Variants Currently In Circulation, Proceedings of the National Academy of Sciences (2020). DOI: 10.1073 / pnas.2008281117
Walter Reed Army Institute of Research
Minimal SARS-CoV-2 diversity suggests a global vaccine is possible (2020, September 1).
accessed on September 1, 2020
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