> "We generated chimeric recombinant SARS-CoV-2 encoding the S gene of Omicron in the backbone of an ancestral SARS-CoV-2 isolate and compared this virus with the naturally circulating Omicron variant. The Omicron S-bearing virus robustly escapes vaccine-induced humoral immunity, mainly due to mutations in the receptor-binding motif (RBM), yet unlike naturally occurring Omicron, efficiently replicates in cell lines and primary-like distal lung cells. In K18-hACE2 mice, while Omicron causes mild, non-fatal infection, the Omicron S-carrying virus inflicts severe disease with a mortality rate of 80%. This indicates that while the vaccine escape of Omicron is defined by mutations in S, major determinants of viral pathogenicity reside outside of S."
https://www.biorxiv.org/content/10.1101/2022.10.13.512134v1....
See russfink comment above for the relative mortality compared to the original Wuhan strain (100% for Wuhan compared to 80% for this hybrid). So this researcher-generated strain appears to be intermediate in mortality between the original Wuhan strain and Omicron, BUT it escapes vaccination relative to the Wuhan strain, making it more dangerous in that regard and more likely to spread through a vaccinated population causing significant mortality. I'd classify this as reckless and irresponsible research.
As far as the original Wuhan strain, we have about four theories of origin. (1) natural wild type with no lab research involvement, (2) natural wild type collected by a lab and accidentally released from that lab, (3) wild type 'heated up' by serial passage through mice and cloned human-type cells without explicit genetic engineering, and (4) deliberate engineering using a CRISPR system to insert a furan cleavage site in a collected wild-type virus, which allowed a bat virus to leap to a human host.
Really (4) has the most evidence at this point, and note that this is not entirely the fault of the Chinese Wuhan Institute of Virology as the research concept was partially developed in the USA and continued (despite an Obama-era ban on gain-of-function research) in China with Ecohealth Alliance funding.
As far as why doing gain-of-function research to predict 'emerging disease outbreaks' is a godawfully stupid idea, it's that it appears that almost any infectious animal virus can be converted to a human pathogen by selective transfer of human-receptor-binding motifs, even though such transfer would never take place under natural conditions. An immediate global ban on this kind of research (under the Biological Warfare Convention) is needed.