The Spike Ferritin Nanoparticle (SpFN) vaccine is a protein subunit vaccine candidate developed by scientists at the Walter Reed Army Institute of Research (WRAIR). It was created to develop a “pan-coronavirus” technology that could offer protection against multiple coronavirus strains. The vaccine uses a well-studied ferritin platform and is designed to address the challenge of new and emerging coronavirus variants that can reduce the effectiveness of existing vaccines.
The Pan-Coronavirus Goal
The emergence of variants such as Delta and Omicron demonstrated how genetic changes could allow the virus to partially evade the immunity generated by previous infection or vaccination. This constant viral evolution necessitates the development of next-generation vaccines that can provide broader and more durable protection. The goal is to move beyond reactionary vaccine updates for each new variant.
Researchers at WRAIR are pursuing a “pan-SARS” strategy aimed at creating a single vaccine that is effective against a wide range of coronaviruses. The objective is to develop a preemptive tool that could defend against future SARS-CoV-2 variants as well as other related coronaviruses that might transfer from animals to humans in the future. The aim is to create a vaccine that offers safe and effective protection against multiple coronavirus species and strains.
How the Nanoparticle Platform Works
The SpFN vaccine’s technology is based on a protein called ferritin, which naturally assembles into a spherical nanoparticle shape with 24 distinct faces. This structure acts as a versatile platform, much like a soccer ball. Scientists attach fragments of the coronavirus spike protein, the part of the virus that it uses to enter human cells, onto these multiple faces. The spike protein used is derived from the original Wuhan strain and is modified to be more stable.
This design allows the vaccine to present the immune system with numerous copies of the spike protein in a highly organized and repetitive pattern. Unlike vaccines that present a single version of the spike protein, the multi-faceted display on the nanoparticle may stimulate a more potent and broader immune response. This method is intended to train the immune system to recognize a wider array of coronavirus threats, including different variants and potentially other coronaviruses like SARS-CoV-1. The vaccine is also mixed with an adjuvant, a substance that helps enhance the immune response to make it stronger and longer-lasting.
Clinical Trial Findings and Safety
The SpFN vaccine entered a Phase 1 human clinical trial in April 2021 to evaluate its safety and ability to generate an immune response. The study enrolled healthy adults between the ages of 18 and 55 who had not been previously infected with COVID-19 or vaccinated against it. This first-in-human trial was sponsored by the U.S. Army Medical Research and Development Command.
Results from preclinical studies in nonhuman primates were promising, showing the vaccine elicited a strong immune response. It generated effective neutralizing antibodies against the original SARS-CoV-2 strain and major variants of concern, as well as the SARS-CoV-1 virus. The early human trial data is intended to show whether this broad protection seen in animal studies translates to humans.
Future Development and Availability
The SpFN vaccine is still in the clinical development phase and is not yet available to the public. Following the completion of the Phase 1 trial, the next steps involve larger, later-stage trials to continue to assess its effectiveness and safety in a broader population. The initial analyses from the first human trial were anticipated to conclude and provide insights into the vaccine’s performance in humans.
The development of this vaccine is part of a long-term strategy to build a platform that can be adapted for future disease threats. The investment in a next-generation vaccine technology is seen as a foundational step toward preparing for and potentially preventing future pandemics caused by coronaviruses. WRAIR’s work on this candidate contributes to a global effort to create more universal vaccine solutions that are not limited to a single, specific viral strain.