Studies suggest that new California variants may be causing the virus to surge

In late December, California scientists began searching for coronavirus samples to find new and rapidly spreading variants that had just been identified in the United Kingdom.

They found it, but with a relatively small number of samples. But in the process, scientists made another unwelcome discovery. California has created its own variant.

The mutant, which belongs to a lineage known as CAL.20C, appeared to have appeared in July, but remained sluggish until November. Then it soon began to spread.

According to a new study that has not yet been published, CAL.20C accounted for more than half of the viral genome samples collected at the Los Angeles laboratory on January 13.

“We had our own problems not crossing from Europe,” said Jasmine Plummer, a research scientist at the Cedars Sinai Medical Center in Los Angeles. “It really started here, and it had the opportunity to appear during the holidays and start to surge.”

There is no evidence that CAL.20C is more deadly than other variants. Scientists also need to do more research to determine if CAL.20C is actually more contagious than other forms of the virus.

However, Eric Vail, director of molecular pathology at Cedars-Sinai, said CAL.20C could play a major role in the surge in incidents that overwhelmed hospitals in Southern California. “I’m pretty sure this is a more infectious strain of the virus,” said Dr. Bale.

Dr. Charles Chiu, a virologist at the University of California, San Francisco, said he and his colleagues found variants in about 20 to 30 percent of the sequenced samples throughout the state. “It just appeared under our nose and is now rising in multiple counties,” he said. “Overall, it’s no exaggeration to say that it extends outside California.”

Researchers are also looking for CAL.20C in other states, according to Dr. Plummer, and have been found in Arizona, Connecticut, Maryland, New Mexico, Nevada, New York, Texas, Utah, Washington, and Wyoming. .. District of Columbia. It’s not yet clear how common it is outside of California.

Last week, the US Centers for Disease Control and Prevention issued a formal warning about variants attacking the United Kingdom. The mutant, called B.1.1.7, is still relatively rare in the United States and accounts for less than half of the infection, officials said it could be. Responsible for most national cases By March.

An agency spokesman said the CDC would work with California to learn more about the new variant. “Currently, it is unclear whether this variant differs from other SARS-CoV-2 viruses, whether those differences may have contributed to its appearance, or whether this appearance was merely a random event. “He said.

“I think this particular variant is remarkable,” said Kristian Andersen, a virologist at the Scripps Research Institute, who discovered one of the first samples of B.1.1.7 in the United States. But he warned that it is still unclear whether CAL.C20 has become more common because of its biological benefits, or by chance.

If both B.1.1.7 and CAL.C20 are more contagious than the other variants, it is not clear how the conflict between the two will be resolved. “CAL.C20 is off to a great start,” said Dr. Bale. “Even if B.1.1.7 is generally highly infectious, we may not see a significant surge from B.1.1.7 here in LA.”

Since scientists first identified the new coronavirus in China a year ago, they occur randomly and new mutations that are inherited by the new generation of viruses as they replicate in our bodies. I have been tracking the appearance of.

Many mutations are harmful to the virus and exacerbate replication. Many others are neutral. However, researchers have found some of the concerns because the virus seems to help infect people more efficiently.

In the early months of the pandemic, mutations occurred in the lineage, which subsequently became dominant in many parts of the world.Known as D614G, Mutations are now believed to infect the virus more easily from person to person compared to mutants without it.

In December, British researchers discovered B.1.1.7. It is about 50% more infected than previous versions of the virus. This variant is currently driving a surge in cases and hospitalizations.

B.1.1.7 was in the United States in early November. Research Posted online Tuesday by biologists Brendan Larsen and Michael Worobey of the University of Arizona. This means that it was circulating for two months before the variant was detected.

In California, researchers looking for B.1.1.7 have begun to notice abnormal mutations in their samples. A mutation called L452R changes the shape of a protein called spikes that decorates the surface of the coronavirus.

“We came across this truly unexpected discovery and implemented it from there,” said Dr. Bale.

Mutations have appeared in various viral strains over the past year. Scientists have studied L452R because it may help the coronavirus attach to our cells and infect them.

In California, Dr. Bale, Dr. Plummer and his colleagues discovered that each time they encountered a mutant with the L452 mutation, they also had four other characteristic mutations. They said the combination showed that they were dealing with a single lineage that emerged at some point in California. Researchers have named the virus with all five mutations CAL.C20.

The California Department of Health held a press conference on Sunday night to announce that the L452 mutation is becoming more common in California. On Monday night, Cedars-Sinai released a news release on the study. This will soon be posted on the preprint website MedRxiv.

The Cedars-Sinai team is part of a state-wide network of researchers tracking coronavirus mutations. They randomly selected nasal swabs from Covid-19-positive patients and collected genetic material from the swabs.

Researchers stitched together fragments to reconstruct the entire viral genome and look for characteristic mutations. They then compared their findings to other viral genomes sequenced state and country-wide.

Researchers discovered the earliest sample of CAL.C20 in July in Los Angeles. They couldn’t find another sample until October. Subspecies became more common in November, reaching 36% of samples from Cedars Sinai in December and 50% last week.

External scientists are concerned about new discoveries, but say it’s still unclear whether mutations in California variants give it an edge, or whether it happens to be more common.

For example, the sample that scientists are looking at can be biased. It’s possible that CAL.C20 happened to be popular, thanks to some big superspreading events.

“I think we need to be careful before concluding that certain strains are spreading because of the benefits of transmission, not because of riding the waves caused by human behavior,” Dr. Wolobay said.

If it turns out to be more contagious, Dr. Plummer said CAL.C20 may prove to be partially responsible for the recent surge in catastrophic cases in Southern California hospitals. Told.

As the total number of cases increased, Dr. Plummer and her colleagues found that the proportion of CAL.C20 also increased. This is consistent with the idea that this is a more contagious variant. “That is, the numbers speak for themselves,” she said.

Dr. Chiu also said that this variant is involved in many outbreaks that have infected many people. “There are signs of concern that this variant may be highly contagious,” he said.

Dr. Chiu and his colleagues are currently multiplying mutants in cells to see how fast they grow compared to other mutants. Researchers will also observe how well the vaccine-produced antibodies work against CAL.C20.

Other scientists are also investigating the increased frequency of variants in California. They are looking for evidence that can determine if biology or chance is due to its rise.

“That’s the work that needs to be done,” said Dr. Bale. “We don’t have that information.”