With new COVID variants and subvariants evolving faster and faster, each chipping away at the effectiveness of the leading vaccines, the hunt is on for a new kind of vaccine–one that works equally well on current and future forms of the novel-coronavirus.
Now researchers at the National Institutes of Health in Maryland think they’ve found a new approach to vaccine-design that could lead them to a long-lasting jab. As a bonus, it also might work on other coronaviruses, not just the SARS-CoV-2 virus that causes COVID.
The NIH team reported its findings in a peer-reviewed study that appeared in the journal Cell Host & Microbe earlier this month.
The key to the NIH’s potential vaccine design is a part of the virus called the “spine helix.” It’s a coil-shaped structure inside the spike protein, the part of the virus that helps it grab onto and infect our cells.
Lots of current vaccines target the spike protein. But none of them specifically target the spine helix. And yet, there are good reasons to focus on that part of the pathogen. Whereas many regions of the spike protein tend to change a lot as the virus mutates, the spine helix doesn’t.
That gives scientists “hope that an antibody targeting this region will be more durable and broadly effective,” Joshua Tan, the lead scientist on the NIH team, told The Daily Beast.
Vaccines that target and “bind,” say, the receptor-binding domain region of the spike protein might lose effectiveness if the virus evolves within that region. The great thing about the spine helix, from an immunological standpoint, is that it doesn’t mutate. At least, it hasn’t mutated yet, three years into the COVID pandemic.
So a vaccine that binds the spine helix in SARS-CoV-2 should hold up for a long time. And it should also work on all the other coronaviruses that also include the spine helix–and there are dozens of them, including several such as SARS-CoV-1 and MERS that have already made the leap from animal populations and caused outbreaks in people.
To test their hypothesis, the NIH researchers extracted antibodies from 19 recovering COVID patients and tested them on samples of five different coronaviruses, including SARS-CoV-2, SARS-CoV-1 and MERS. Of the 55 different antibodies, most zeroed in on parts of the virus that tend to mutate a lot. Just 11 targeted the spine helix.
But those 11 that went after the spine helix worked better, on average, on four of the coronaviruses. (A fifth virus, HCoV-NL63, shrugged off all the antibodies.) The NIH team isolated the best spine-helix antibody, COV89-22, and also tested it on hamsters infected with the latest subvariants of the Omicron variant of COVID. “Hamsters treated with COV89-22 showed a reduced pathology score,” the team found.
The results are promising. The researchers stated that they have identified a new class of antibodies that can broadly neutralize [coronaviruses] and target the stem helix.
Don’t break out the champagne quite yet. The NIH team cautioned that, although these data can be useful in vaccine design, they haven’t performed vaccine experiments and therefore cannot draw any conclusive conclusions regarding the effectiveness of stem helix vaccines.
It’s one thing to test a few antibodies on hamsters. But it’s quite another thing to create, test and receive approval for a new type of vaccine. “It is really hard and most things that start out as good ideas fail for one reason or another,” James Lawler, an infectious disease expert at the University of Nebraska Medical Center, told The Daily Beast.
And while the spine-helix antibodies appear to be broadly effective, it’s unclear how they stack up against antibodies that are more specific. A spine-helix vaccine might be effective against many viruses but not all. It will work differently against specific viruses than one that is tailored for it. Tan stated that further experiments are needed to determine if the spine-helix antibody will provide sufficient protection in humans.
There’s a lot of work to do before a spine-helix vaccine might be available at the corner pharmacy. And there are a lot of things that could derail that work. Additional studies could contradict the NIH team’s results. It is possible that the new vaccine design does not work on humans as it did on hamsters.
The new jab could also turn out to be unsafe, impractical to produce or too expensive for widespread distribution. Barton Haynes from Duke University, an immunologist said that he reviewed spine-helix vaccine designs last spring and decided they were too expensive to justify major investments. The main problem, he said, is that the spine-helix antibodies are less potent and “tough to induce” from their parent B-cells.
The harder the pharmaceutical industry has to work to produce a vaccine, and the more vaccine it has to pack into a single dose in order to compensate for lower potency, the less cost-effective a vaccine becomes for mass-production.
Maybe a spine-helix jab is in our future. Or maybe not. It doesn’t matter. Scientists are still making progress towards a universal coronavirus vaccine .. One that could work for many years on a wide array of related viruses.
COVID for one isn’t going anywhere. And with each mutation, it risks becoming unrecognizable to the current vaccines. We need a vaccine that is mutation-proof.
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