Omicron mutations signal vaccine breakout, similar symptoms

This colorized scanning electron micrograph of a cell heavily infected with SARS-CoV-2 viral particles (orange / red) was captured at the NIAID Integrated Research Facility in 2020. (NIAID via ZUMA Wire / TNS)

(Tribune News Service) – As fears of a new global wave of COVID-19 cases rock global markets, spur a new round of travel bans and push Americans to rethink their vacation plans, scientists who study the omicron variant are getting the first clues of what to expect in the months to come.

Mutations in the new variant suggest that it is likely to evade vaccine protections to some extent, but that it is unlikely to cause more severe disease than previous versions of the coronavirus.

These early assumptions seem consistent with real-world observations in places like South Africa, where infections have included vaccinated and previously ill people, but so far appear largely benign. These data, however, are so far extremely limited, so much of the current evidence comes from computer modeling and comparing the physical structure of omicron to past variants.

A lot of mystery remains about the omicron, which has more than twice as many mutations as the delta variant, most of it in the peak, the crown-shaped protein on the surface of the virus that vaccines cause. our body to attack. The emergence of such a highly mutated virus almost two years after the start of the pandemic surprised the scientific community, as many had speculated that the ultra-contagious delta variant could mark the last major wave, peaking then s ‘extinguishing, much like the 1918 influenza pandemic.

It will take scientists weeks of careful laboratory testing and studies to unravel exactly what mutations in omicron mean and definitively determine just how more contagious it is and what the implications are for those infected. But the first observations have already allowed scientists to make educated guesses about what is to come.

The location of the omicron mutations suggests two things. The first is that the virus is likely to escape vaccines to some extent. Some of the peak mutations are found in the same locations as those seen in other variants that spread rapidly. In past variants, these mutations have led to what is known as antibody leakage, in which the virus is able to escape attack from antibodies generated by vaccines or a previous infection with COVID-19.

The second idea is that it seems likely that the omicron is not impermeable to the body’s second line of defense, the T cells. They work hand in hand with antibodies to prevent infection and disease development. . If a virus manages to escape attack by the antibodies, the T cells then go to work, killing the infected cells.

“A lot of mutations occur in the hotspots of the spike protein, which we know are important for antibody binding,” said Wendy Burgers, immunologist at the University of Cape Town. “What we are predicting is that a large part of the T cell response will still be active against the omicron.”

His lab is awaiting samples from patients infected with omicron and advanced omicron-based proteins to begin experiments to confirm this suspicion. But the first computer analyzes confirmed the theory.

The antibodies have tight attack targets on the spike protein, targeting only two specific regions known as the receptor binding domain and the N-terminal domain. This means that a handful of mutations in these regions can have a significant impact on the ability of antibodies to attack.

T cells, on the other hand, target the entire tip. A handful of changes are less likely to impact their effectiveness.

“What we need to confirm with our lab experiments is to what extent the T cell response is affected?” she said.

While some of the dozens of omicron mutations have already been seen in previous variants, many are completely new. This means that more time and data will be needed to fully understand the full impact of omicron with certainty.

At Rockefeller University in New York, Theodora Hatziioannou’s lab spent the last year experimenting with a synthetic, safe version of the virus to see what might happen if there were a significant number of spike protein mutations. COVID-19, many in the same locations as omicron.

“We can be quite confident that this new peak is going to be quite resistant to neutralization by antibodies,” she said. “I hope that this omicron spike doesn’t escape every response from our immune system and that vaccines will always offer some protection against serious illness.”

In the long run, what these mutations highlight is that predictions about the pandemic are difficult to make.

Charles Chiu, a microbiologist at the University of California at San Francisco whose lab sequenced the first known U.S. case of omicron, said he was on the side of scientists who suspected the delta variant was the beginning of the end. of the pandemic.

“I was surprised by omicron,” he said. “It’s a virus that has constantly surprised us.”

Even though omicron doesn’t lead to more serious infections for most people, he said, an increase in the number of cases would lead to more hospitalizations and deaths simply because of the number of infections. And as long as there are large numbers of unvaccinated people in the world, the virus will continue to spread and mutate.

Omicron also presents further evidence that SARS-CoV-2 is highly adaptable and can be difficult to eradicate completely. Public health policy may need to move away from the goal of trying to get the virus out of circulation through vaccination and instead focus on preventing serious illness, Chiu said.

“It is very possible that this virus is here to stay,” he said.


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