New research led by Penn State reveals that mutations led to the stem of the SARS-CoV-2 spike protein becoming progressively tighter over time, which may have improved the virus’s ability to transmit through nasal droplets and infect host cells once in the body. Credit: Ganesh Anand, Penn State
Key points:
- The stem of SARS-CoV-2 spike proteins have become tighter over time, increasing the virus’ ability to spread.
- The Omicron variants have the strongest stem yet, explaining why vaccines based on older variants are not as effective.
- Researchers believe the spike proteins are now twisted so tightly that it’s unlikely to structurally change.
A research team from Penn State recently discovered that a 6-pack of abs not only makes humans stronger, but viruses as well.
In a new study, scientists have shown that the stem region of the spike protein on SARS-CoV-2 became progressively tighter over time, improving the virus’s ability to transmit through nasal droplets. For example, the stem region of the protein in the most recent Omicron variant is as rigid as it can get.
Studying the virus in vitro using a technique called amide hydrogen/deuterium exchange mass spectrometry, the researchers discovered that the spike protein stem first became more rigid with the D614G mutation, which is common to all SARS-CoV-2 variants. The stem became progressively more twisted with the emergence of new mutations in subsequent variants, and the Omicron BA.1 variant showed the largest magnitude increase in stabilization relative to preceding variants.
“A tighter core could likely make the virus more stable in nasal droplets and faster at binding to and entering host cell,” said Ganesh Anand, associate professor of chemistry at Penn State.”
So, for example, what initially took about 11 days to develop an infection after exposure now takes only about four days.”
One of the reasons the vaccines have not been able to fully neutralize the virus, Anand said, is because they were generated against the spike protein of the original wild-type variant.
“The latest bivalent booster—which targets newer variants—helps, but people who never got this booster aren’t receiving this more targeted protection,” the chemistry professor explained. “Future vaccines that focus specifically on Omicron are likely to be effective for longer.”
According to Anand, the spike protein has now become so tightly twisted that it is unlikely to structurally change further at the stem region.
“There are limits to how much it can tighten,” he said. “I think that we can have some cautious optimism, in that we’re not going to continuously have variants emerging, at least tightening is not going to be a mechanism.”