A Japanese study on Corona: The ghost Omicron strain is more dangerous than the original

The basic reproductive number of the PA2 strain is 1.4 times higher than that of the original Omicron strain PA1.

A recent study has found that the stealth omicron strain BA 2 may be more dangerous than the original omicron strain, known as BA1.

The study, which was published Wednesday in preprint on bioRxiv , was conducted by researchers in Japan and has not yet been reviewed by other scientists.

What is the difference between the original Omicron Corona strain, the ghost strain and the Corona Virus New Cove Infographic

Brenda Goodman, in a report on CNN, wrote that the " PA2 " virus - one of the strains of the Omicron virus - not only spreads faster than the Omicron, but may also cause a more serious disease.

New lab experiments from Japan show that PA2 may have properties that make it capable of causing serious illness, such as older variants of Covid-19, including Delta.

'Ghost' escapes vaccine immunity

Like Omicron, the ghost strain appears to largely escape vaccine-induced immunity. PA2 also does not respond to some treatments, including sotrovimab, the monoclonal antibody currently used against Omicron.

Usually, before a study is published in medical journals, it is examined by independent experts. Pre-prints allow research to be shared more quickly, and are published before further review.

In the study, the researchers wrote that the basic reproductive number of the "PA2" strain is 1.4 times higher than that of the original Omicron strain "PA1".

And the basic reproductive number - its symbol (R0) and pronounced "R-naught" or "R-zero" - indicates the average number to whom an infected person is expected to transmit the disease, so if a particular virus (R0) equals 3, This means that each patient will pass the disease on to 3 other people.

And more able to reproduce

Cell culture experiments showed that the ghost strain was more capable of replicating or reproducing in human nasal epithelial cells.

Furthermore, hamster infection experiments have shown that PA2 is more pathogenic than PA1.

"Our multiscale investigations indicate that the public health risk of PA2 strain is potentially higher than PA1," the researchers said.

"It may be, from a human perspective, that there is a virus worse than PA1 and it may be able to transmit better and cause worse disease," said Dr. Daniel Rhodes, chief of microbiology at the Cleveland Clinic in Ohio, USA.

Rhodes reviewed the study but was not involved in the research.

PA2 is highly mutated compared to COVID-19

The director of the US Centers for Disease Control and Prevention, Dr. Rochelle Walinsky, said the CDC is closely monitoring PA2.

"There is no evidence that PA2 is more dangerous than PA1," she said on Friday. She added that they continue to monitor variables that are circulated locally and internationally, and "monitor data arising from disease severity in humans and findings from papers such as these conducted in laboratory conditions."

PA2 is highly mutated compared to the original virus that causes Covid-19, which appeared in Wuhan, China. It also has dozens of genetic changes that differ from the original Omicron strain, making it distinct from the Alpha, Beta, Gamma and Delta variants.

Is PA2 a new species?

Kei Sato, the researcher at the University of Tokyo who conducted the study, argues that these results prove that PA2 should not be considered a type of omicron and that it needs to be closely monitored.

He told CNN that creating a method for specifically detecting PA2 would be the first thing many countries would have to do.

The BA2 strain has genetic mutations that researchers worry may make it more difficult to identify than the BA1 strain.

The PA1 version of the Omicron strain is relatively easier to track than the previous strains, due to the fact that it does not have one of the 3 genes targeted by the PCR test.

PA2 (the original omicron) does not have this missing target gene. Instead, scientists monitor them the way they did previous strains, including the Delta strain, by tracing the genetic maps of viruses submitted to public databases.

PA2 has been estimated to be 30% more prepared than Omicron. According to the World Health Organization, it has been detected in 74 countries and 47 US states.

Monoclonal resistance

The new study found that PA2 can replicate itself in cells more quickly than PA1 - the original version of Omicron. It is also more adept at making cells stick together. This allows the virus to form larger clumps of cells, called syncytia, than PA1.

This is worrying because these blocks then become factories to produce more copies of the virus. Delta was also good at creating syncytial creatures, which is thought to be one reason why they are described as so destructive to the lungs.

When the researchers infected hamsters with BA2 and BA1, the animals infected with BA2 became sick and had worse lung function.In tissue samples, the lungs of hamsters infected with BA2 were more damaged than Those infected with PA1.

Similar to the original Omicron, PA2 was able to penetrate the antibodies into the blood of people who had been vaccinated against corona.

It was also resistant to the antibodies of those infected with COVID-19 early in the epidemic, including alpha and delta. PA2 was almost completely resistant to some monoclonal antibody treatments.

Bright spot

But there was a bright spot, as it appears that antibodies in the blood of those recently exposed to Omicron offer some protection against PA2, especially if they have also been vaccinated.

This raises an important point, says Deborah Fuller, a virologist at the University of Washington School of Medicine who reviewed the study, but was not part of the research.

Fuller says that although PA2 appears to be more contagious and pathogenic than Omicron, it may not cause a more harmful wave of Covid-19 infection.

"One caveat that we have to think about, when we get new variants that may seem more dangerous, is the fact that there are two sides of the story: our immune system is developing as well, and that makes things go backwards."

A race against Corona and its variants

Right now, says Fuller, "we're in a race against the virus, and the main question is: Who's on top?

"What we ultimately want is for the host to be ahead of the virus. In other words: our immunity is one step ahead of the next strain that emerges, and I don't know we've come that far yet."

That's why, Fuller says, she feels it's not yet time for communities to lift the masks.

"We were about 10 feet from the finish line. It's not a good idea to take the masks off now. It's just going to extend it. Let's get to the finish line."