In late December, scientists in California began searching for samples of coronavirus for a rapidly spreading new variant that had been identified in the UK.
He found it, although in relatively few specimens. But in the process, scientists made another unwanted discovery: California had produced a version of its own.
The mutant, who is of the lineage known as CAL.20C, appears to have popped up in July but was short until November. Then it started spreading rapidly.
CAL.20C accounted for more than half of the virus genome samples collected in the laboratories of Los Angeles on January 13, according to a new study, which has not yet been published.
“We had our own problems that did not cross Europe,” said Jasmine Plummer, a research scientist at Cedar-Sinai Medical Center in Los Angeles. “It really originated here, and it got a chance to grow and grow on vacation.”
There is no evidence that CAL.20C is more lethal than other variants. And scientists will have to do more research to determine if CAL.20C is actually more contagious than other forms of the virus.
But Eric Well, director of molecular pathology at Cedars-Sinai, said it was possible that CAL.20C was playing a big role in the increase of cases that have overwhelmed Southern California hospitals. “I am convinced that this is a more contagious strain of the virus,” Dr. Well said.
Dr. a virologist at the University of California at San Francisco. Charles Chiu said that across the state, he and his colleagues are getting versions of about 20 percent to 30 percent of the samples. “It popped up just under our noses, and now it’s growing in many counties,” he said. “Overall, it’s safe to say that it’s going to spread outside of California.”
Researchers are also looking in other states for CAL.20C, Drs. Plummer said, and so far has been found in Arizona, Connecticut, Maryland, New Mexico, Nevada, New York, Texas, Utah, Washington and Wyoming, as well as the District of Columbia. It is not yet clear how common this is outside of California.
Last week the Centers for Disease Control and Prevention formally warned Britain to swallow. Although that mutant, called B.1.1.7, is still relatively rare in the United States, accounting for less than one-half percent of infections, the agency said it should be responsible for most cases in the country by March Can.
An agency spokesman said the CDC is working with California to learn more about the new version. “Currently, it is not known whether this variant differs from other SARS-CoV-2 viruses, whether those differences may have contributed to its emergence, or whether this emergence was simply a random event,” he said .
Christian Anderson, a virologist at the Scripps Research Institute, said, “I am the one to see this in particular. I discovered one of the first specimens of B.1.1.7 in the United States. But he cautioned that it still It is unclear if CAL.20C is becoming more common because it has some biological benefit, or just by coincidence.
If both B.1.1.7 and CAL.20C are more contagious which are the other variants, then it is unclear how a competition between them will settle. “CAL.20C has a big start,” Dr. Well said. “Even though B.1.1.7 is more contagious overall, we can never see a bigger jump here than in LA”
Since scientists first identified the new coronovirus in China a year ago, they have been tracking the emergence of new mutations, which are randomly generated and reach new generations of viruses as they enter our bodies Let’s repeat.
Many mutations are harmful to the virus and make it worse in replication. Many others are neutral. But researchers have now made several discoveries that are worrying because they help people more efficiently infect the virus.
In the early months of the epidemic, a mutation originated in a lineage, which then became prominent in most parts of the world. Known as D614G, the mutation is now believed to allow the virus to be easily transported from one person to another, with variants without it.
In December, researchers in the UK found B.1.1.7, about 50 percent more infectious than previous versions of the virus. The variant is now a driving factor in the growth of cases and hospitals.
According to a study posted online Tuesday by University of Arizona biologists Brendan Larsen and Michael Warbey, B.1.1.7 was in the United States in early November. This would mean that the variant had been running for two months before being detected.
In California, researchers searching for B.1.1.7 began to notice an unusual mutation in their samples. The mutation, called L452R, changes the shape of a protein, called a spike, that decorates the surface of the coronovirus.
“We actually stumbled upon the unexpected discovery and went from there,” Dr. Well said.
Mutations have occurred in various viral lineages in the last one year. Scientists have studied L452R because it can help coronaviruses stick to our cells and infect them.
In California, Drs. Well, Dr. Plummer and his colleagues found that whenever they came across a variant with the L452 mutation, they also committed four other distinct mutations. That combination, he said, indicated that they were working with a single lineage that had emerged at some point in California. Researchers named all five mutations any virus carrying the CAL.20C.
The California Department of Health announced at a news conference Sunday night that the L452 mutation was becoming common in California. On Monday night, Cedars-Sinai released a news story about its study, which will soon be posted on the preprint website MedRxiv.
The Cedar-Sinai team is part of a statewide network of researchers that monitor mutations in coronoviruses. They randomly selected nasal swabs from patients who tested positive for Kovid-19, and then collected genetic material from the swab.
The researchers linked the fragments together to recreate the entire genome of the virus and then looked for specific mutations. They then compared their findings to other viral genomes sequenced in the state and country.
The researchers found the earliest sample CAL CALC in July in Los Angeles. He did not receive another specimen until October. The version became more common in November, reaching 36 percent of the samples from Cedar-Sinai in December and 50 percent the previous week.
External scientists are concerned about the new findings, but say it’s still unclear whether the California version’s mutations are giving it an edge – or whether it’s just coincidentally showing that.
For example, samples that scientists have observed may have a bias. It is also possible that CAL.20C became more common thanks to some large super-spreader events.
“I think we need to be careful before concluding that a particular lineage is spreading due to a transmission advantage, as it has happened to ride the wave caused by human behavior,” Dr. Vorobe said.
If it becomes more contagious, Drs. Plummer said, CAL.20C may be partially responsible for recent crippling cases in hospitals in Southern California.
As the total number of cases increased, Drs. Plummer and his colleagues found, the percentage of CAL.20C also increased. This would be consistent with the idea that it is the more infectious version. “I mean, the numbers speak for themselves,” she said.
Dr. Chiu also mentioned that this version was involved in several outbreaks, where a large number of people were infected. “There are worrying signs that this version may be highly variable,” he said.
Dr. Chiu and his colleagues are now increasing fractions in cells to see how quickly they multiply with other variants. Researchers are also going to observe how well the antibodies produced by the vaccine work against CAL.20C.
Other scientists are also looking more closely at the increase in version frequency in California. They are searching for evidence that can determine whether biology or chance is to blame for its rise.
“That’s the work that needs to be done,” Dr. Well said. “We don’t have that information.”