New York: Researchers have identified why Omicron sub-variants are better, than previous Covid-19 variants, at escaping detection by the human body's immune cells. In addition to antibodies produced either by vaccines or exposure to earlier versions of the virus, these viral variants must also avoid 'killer' T cells, to sicken people. T cells are immune cells that are unleashed when the immune system detects foreign pathogens.
To understand how Omicron breaks all these barriers, a team from the Yale University in the US, measured activity of MHC (major histocompatibility complex) molecules that present fragments of viruses for recognition by appropriate T cells. These MHC molecules alert the T cells of foreign pathogens that then become targets for the T cells. The researchers found that the activity of these MHC molecules was substantially lower in cells exposed to five Omicron sub-variants of SARS-CoV-2 as well as earlier versions of the virus.