Infection
Omicron Sub-Variant ‘BA.5’ Shows Higher Virulence in Early Infection: Study
Sep
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(IANS)
Omicron sub-variant BA.5 is more virulent due to its ability to rapidly replicate early during infection, according to research.
Since the start of the COVID-19 pandemic in 2019, the SARS-CoV-2 virus has produced several variants, including Alpha, Beta, Delta, and Omicron, each with its own sub-variants.
Researchers from Cornell University in the US used genetically engineered mice to compare SARS-CoV-2 omicron sub-variants.
The genetically modified mice, known as K18-hACE2 mice, were used in the research to express a human receptor that allowed SARS-CoV-2 to enter otherwise inaccessible mouse cells.
“One of the findings is that the strain causing more pathology, BA.5, replicates much faster early on during infection,” said Avery August, Professor of Microbiology and Immunology in the College of Veterinary Medicine (CVM).
“By doing that, the virus generates a very strong immune response, which then leads to increased pathology and symptoms compared to sub-variants that don’t replicate as fast,” August said.
In the research, published in the journal Science Advances, the team found that early Omicron BA.1 and BA.2 subvariants also replicated and spread in the K-18 mice, but they caused minimal illness and death.
On the other hand, BA.5-infected mice exhibited significant weight loss, high pathology in lungs, high levels of inflammatory cells, and cytokines, signalling proteins associated with inflammation.
While some 3-month-old mice survived, all 5 to 8-month-old BA.5-infected mice died. The animal model makes it possible for researchers to begin to dissect components of the immune system that could be focused on or blocked to potentially reduce or eliminate the disease.
Some scientists believe that targeting cytokines with drugs could provide a potential treatment that moderates the immune response and lessens symptoms. The researchers found many similarities between the mouse model and how these sub-variants behave in humans, with BA.5 being more virulent in both.
One significant difference was that most people who developed illness from BA.5 didn’t die, but in K-18 mice, the sub-variant was particularly pathogenic and lethal.
An advantage of the mouse model is that all the mice are identical with the same genetic background. When studying humans, many variables, such as previous conditions, genetics, and whether someone has previously been immunised or infected, can affect the pathological outcome of the disease.
Also, the mouse model allowed the researchers to examine disease in the lungs over time. “With BA.5, we see more pathology early on during the infection compared to mice infected with other strains or the control mice,” August said.
They also found higher viral loads in the strain that caused more infection, he said. Older mice were more affected by the virus than younger mice as well.
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The above article has been published from a wire source with minimal modifications to the headline and text.
