The Omicron subvariants BA.4 and BA.5 are the most prevalent coronavirus strains globally, according to the World Health Organization (WHO).
Recent studies on Covid-19, including preliminary research results, indicate that reinfections and serious conditions may be more common with BA.5 infection.
Compared with the earlier Ômicron subvariant, BA.2, BA.5 is associated with greater odds of causing a second SARS-CoV-2 infection, regardless of vaccination status, a study from Portugal suggests.
From late April to early June, researchers evaluated 15,396 adults infected with the BA.2 variant and 12,306 infected with BA.5. Vaccines and boosters were equally effective against both substrains, according to a report published Monday on medRxiv ahead of the peer review.
However, 10% of BA.5 cases were reinfections, compared to 5.6% of BA.2 cases, suggesting a reduction in the protection afforded by previous infection against BA.5 compared to BA.2, said the researchers. researchers.
In addition, vaccines appeared to be less effective in reducing the risk of serious outcomes for BA.5 compared to BA.2.
“Among those infected with BA.5, booster vaccination was associated with a 77% and 88% reduction in the risk of hospitalization and death from Covid-19, respectively, while greater risk reduction was found for cases of BA.2, with 93% and 94%, respectively,” the researchers wrote.
While “Covid-19 booster vaccination still offers substantial protection against serious outcomes following BA.5 infection,” they said, their findings provide “evidence for adjusting public health measures during the BA.5 outbreak.”
Virus Spike protein damages heart muscle cells
The Spike protein, present on the surface of the coronavirus, used to invade heart muscle cells, also triggers a harmful attack by the immune system, according to new research.
The Spike protein of SARS-CoV-2 interacts with other proteins in heart myocytes (muscle tissue cells) to cause inflammation, researchers said Wednesday in a presentation at the American Heart Association’s 2022 Basic Cardiovascular Science Scientific Sessions .
In experiments with mouse hearts, comparing the effects of Spike from SARS-CoV-2 and the same protein from a different and relatively harmless type of coronavirus, researchers found that only the protein from the Covid-19 virus caused cardiac dysfunction, increase and inflammation.
Furthermore, they identified that, in infected heart muscle cells, only Spike interacted with so-called TLR4 (Toll-like receptor-4) proteins that recognize invaders and trigger inflammatory responses.
In a deceased patient with Covid-19 inflammation, researchers found SARS-CoV-2 Spike protein and TLR4 protein in heart muscle cells and other cell types. Both were absent in a biopsy from a healthy human heart.
“This means that once the heart is infected with SARS-CoV-2, it will activate TLR4 signaling,” Zhiqiang Lin of the Masonic Medical Research Institute in Utica, New York, said in a statement.
“We provided direct evidence that Spike protein is toxic to heart muscle cells and reduced the underlying mechanism as Spike protein directly inflames heart muscle cells,” he told Reuters. “More work is being done in my lab to test whether and how Spike protein kills heart muscle cells.”
Omicron-targeted antibody combination approaches human trials
A new combination of monoclonal antibodies can prevent and treat Omicron infections in monkeys, researchers reported Monday in Nature Microbiology.
The antibodies, called P2G3 and P5C3, recognize specific regions of the Spike protein that the SARS-CoV-2 virus uses to enter cells.
“P5C3 alone can block all SARS-CoV-2 variants that dominated the pandemic up to BA.2 from Omicron,” said Didier Trono of the Swiss Institute of Technology in Lausanne.
“P2G3 comes to the rescue as not only can it neutralize all of the earlier variants of concern of SARS-CoV-2, but it can also block BA.4 and BA.5,” he said. “P2G3 is still effective against some BA.2 or BA.4/BA.5 mutations capable of escaping bebtelovimab, the only clinically approved antibody still exhibiting activity against the dominant BA.4/BA.5 subvariants.”
In lab experiments, mutations that can make SARS-CoV-2 variants resistant to P2G3 did not allow P5C3 to escape, and P5C3 escape mutants were still blocked by P2G3, Trono said. “In essence, the two antibodies cover each other, one filling in the other’s gaps and vice versa.”
Aerium Therapeutics plans to start testing the combination in humans next month, said Trono, who is among the company’s founders. If larger trials eventually confirm its effectiveness, the P5C3/P2G3 combination will be given by injection every three to six months in immunocompromised people who do not have a strong response to Covid-19 vaccines, the company said.
(Editor: Bill Berkrot)
Source: CNN Brasil
