evidence: The BA.2.86 variant of omicron is the ancestor of the currently dominating JN.1 and has about 60 more spike protein mutations than the original, or parent, coronavirus, including over 30 more than its close omicron relatives – the early BA.2 variant and the recently dominant XBB.1.5 variant among them. These mutations led scientists to worry that so many changes would make the variant as tough to contain as the initial omicron outbreak in 2021-22. [...] "But BA.2.86 appears to have increased infectivity of human lung epithelial cells compared to all omicron variants, so that’s a little worrisome. And, consistent with infectivity, it also has increased fusion activity with human lung epithelial cells," said Liu, also a professor in the Department of Microbial Infection and Immunity. "That raises a potential concern about whether or not this virus is more pathogenic compared to recent omicron variants." [...] Additional experiments pointed to the potential for BA.2.86 to be more likely to cause severe disease than its omicron relatives. Researchers found BA.2.86 was more efficient at infecting a cell line derived from the human lower airway epithelium in the lung. Infection of these cells is greatly facilitated through a cell surface protein, known as TMPRSS2, to promote membrane fusion, and this protein is a known contributor to SARS-CoV-2 infection and disease symptoms in the respiratory tract.