A vaccine developed by the U.S. military shows promise for providing wide-ranging protection against SARS-CoV-2 variants, as well as other types of coronavirus.
Nonhuman primate studies also indicate that the Spike Ferritin Nanoparticle (SpFN) COVID-19 vaccine, which was developed by researchers at the Walter Reed Army Institute of Research (WRAIR), also elicits a potent immune response.
The SpFN nanoparticle vaccine is based on a ferritin platform. The researchers explain that it is part of the United States' "pan-SARS" strategy to address the current pandemic while also preparing for variants of concern and similar viruses that could emerge in the future.
"The accelerating emergence of human coronaviruses throughout the past two decades and the rise of SARS-CoV-2 variants, including most recently Omicron, underscore the continued need for next-generation preemptive vaccines that confer broad protection against coronavirus diseases," noted Kayvon Modjarrad, MD, PhD, director of the Emerging Infectious Diseases Branch at WRAIR, coinventor of the vaccine and the U.S. Army lead for SpFN. "Our strategy has been to develop a "pan-coronavirus" vaccine technology that could potentially offer safe, effective and durable protection against multiple coronavirus strains and species."
The preclinical studies were published in Science Translational Medicine. They suggested that the SpFN vaccine protects nonhuman primates from disease caused by the original strain of SARS-CoV-2 while inducing highly potent and broadly neutralizing antibody responses against major SARS-CoV-2 variants of concern, including the SARS-CoV-1 virus that emerged in 2002.
"High-dose (50-mcg) SpFN vaccine, given twice 28 days apart, induced a T helper cell 1 (TH1)-biased CD4 TH response and elicited neutralizing antibodies against SARS-CoV-2 wild type and variants of concern, as well as against SARS-CoV-1," the researchers wrote. "These potent humoral and cell-mediated immune responses translated into rapid elimination of replicating virus in the upper and lower airways and lung parenchyma of nonhuman primates after high-dose SARS-CoV-2 respiratory challenge. The immune response elicited by SpFN vaccination and resulting efficacy in nonhuman primates support the utility of SpFN as a vaccine candidate for SARS-causing betacoronaviruses."
SpFN entered phase I human trials in April 2021, with early analyses expected to conclude soon. That will add information about SpFN's potency and breadth in humans and allow researchers to compare SpFN's immune profile to that of other COVID-19 vaccines already authorized for emergency use.
"This vaccine stands out in the COVID-19 vaccine landscape," Dr. Modjarrad added in an Army press release. "The repetitive and ordered display of the coronavirus spike protein on a multi-faced nanoparticle may stimulate immunity in such a way as to translate into significantly broader protection."
"The threat from COVID-19 continues as it evolves, and eventually there will be other emerging disease threats," said Nelson Michael, MD, PhD, director of the CDC at WRAIR. "Our investment in developing a next-generation vaccine is an important step towards getting ahead of COVID-19 and future disease threats."
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