A flurry of recent research on lab animals as well as human tissues are giving the first clues as to the reason Omicron variant causes less severe disease than the previous versions of coronavirus.
In research studies of mice and Hamsters, Omicron produced less-damaging infections which are usually limited to the upper airways which includes the throat, nose and the windpipe. This variant caused less damage to the lungs, in contrast to previous variants that could result in severe scarring and breathing difficulties.
The month of November was when the initial report about the Omicron variant was reported from South Africa, scientists could only guess how it could behave from previous forms from the disease. The only thing they knew was that it was a distinct and alarming mix that included more than 50 mutations in the genome.
Research has previously revealed that certain modifications allowed coronaviruses to latch the cells more strongly. Some of them allowed the virus avoid antibodies, which serve as a first defense against the infection. However, how this new variant could behave inside the body is a mystery.
“You can’t predict the behaviour of virus from just the mutations,” said Dr. Ravindra Gupta, a viral specialist in Cambridge University. University of Cambridge.
In the last month over a dozen research teams including Dr Gupta’s have been observing the latest pathogen in the laboratory, infecting petri dish cells using Omicron as well as spraying it into the nasal passages of animals.
While they were working, Omicron surged across the world, quickly infecting those who had been vaccinated, and had recovered infection.
As cases increased the hospitalisation rate was only moderately up. The first studies on patients showed the possibility that Omicron is less likely to trigger severe disease than other varieties and was particularly effective in those who had been vaccinated. But, the findings came with some warnings.
In one way, the majority of the early Omicron cases were among younger people who are more likely to become seriously ill with all variants that the disease. The majority of these initial cases were occurring for people who have some degree of immunity from prior infections or vaccinations. It was not known if Omicron could be less serious for an older person who had not been vaccinated such as.
Animal studies can help clarify the ambiguities because scientists are able to examine Omicron on the same animals in the same conditions. More than a half-dozen studies published in recent days have all led to the similar result: Omicron appears to be less severe than Delta and the earlier forms of the virus.
This Wednesday (Dec 29) an extensive group composed of Japanese and American researchers published a report about mice and hamsters who were infected with Omicron or any of its earlier variants. The mice infected by Omicron suffered less damage to their lungs as well as lost weight less quickly and had a lower risk to be killed, according to the study.
The animals that were infected by Omicron typically experienced less symptoms, the scientists were struck by the findings in Syrian Hamsters, one species that is known to be extremely sick with earlier variants of Omicron.
“This was surprising, since every other variant has robustly infected these hamsters,” explained Dr. Michael Diamond, a virus specialist in Washington University and a co-author of the study.
A number of other studies conducted on mice and hamsters have come to the similar conclusion. (Like the most urgent Omicron research These studies have been made available on the internet, but haven’t yet been published in journals of science.)
The reason Omicron is less pronounced could be due to anatomical differences. Dr. Diamond and his coworkers discovered that the concentration of Omicron in the nasal passages of hamsters was identical to that in animals by an earlier variant of coronavirus. However, Omicron concentrations in the lungs was one tenth or less than that of the other varieties.
Similar findings were made by researchers from the University of Hong Kong who examined small pieces of tissue from the human airways during surgical procedures. The samples were taken from 12 lung tissues, researchers discovered that Omicron increased in size faster than Delta and other variants.
The study also found that the virus infected cells of the bronchi, which are the tubes that line the chest’s upper part which carry air from the windpipe into the lung. Inside those lung cells, in the initial two days following being infected, Omicron increased quicker then Delta or the coronavirus that caused it did.
The findings must be more research, including tests on monkeys or the examination of the airways in people who are infected by Omicron. If the results stand against scrutiny they could be the reason people with Omicron appear less likely be admitted to hospital than those suffering from Delta.
Coronavirus diseases begin in the nasal area or the mouth and can spread down the throat. In mild cases, they do not go far beyond the point of. However, when coronavirus gets to lung tissue, it may cause serious harm.
Lung immune cells are prone to overreact and kill not just infected ones but healthy ones too. They may cause a rash of inflammation that can damage the delicate lung wall. Furthermore, the virus could escape from damaged lungs and enter the bloodstream, creating blood clots, and then destroying the other organs.
Dr. Gupta believes that his team’s latest research provides a molecular explanation of the reason Omicron isn’t doing as well in lung.
The lung’s cells have a protein called TMPRSS2 on their surfaces that may inadvertently assist viruses to get into the cell. However, Dr Gupta’s group discovered that the protein doesn’t attach to Omicron effectively. In the end, Omicron is less effective of infecting cells in this way than Delta. A team from University of Glasgow University of Glasgow independently came to the similar conclusion.
In a different way coronaviruses also can slip into cells that don’t produce the TMPRSS2 protein. The airway is the highest, and cells do not tend to carry the protein. This could explain why Omicron is detected more frequently than in the lungs.
Dr. Gupta suggested that Omicron changed into a specialist for the upper airway and thrives in the nose and throat. If that’s the case it could mean that the virus has greater chance of being eliminated in tiny drops of the air around it and interacting with new hosts.
“It’s all about what happens in the upper airway for it to transmit, right?” He said. “It’s not really what happens down below in the lungs, where the severe disease stuff happens. So you can understand why the virus has evolved in this way.”
These studies can to explain how Omicron causes milder diseases however, they cannot explain why the Omicron variant is so successful in passing from one person to another. It is estimated that the United States logged more than 580,000 cases of the disease on Thursday alone most of which are believed to have been Omicron.