Boston University scientists have created a hybrid version of the coronavirus that causes COVID-19. Their experiments sparked controversy, with heated headlines claiming that the researchers made the virus more lethal and university officials denouncing these claims as "false and inaccurate."
The new omicron spike-carrying virus — built by attaching the spike protein from an omicron version of the virus to the original SARS-CoV-2 virus — killed 80% of lab mice infected with it, making it more severe than the original omicron variant which didn’t kill any infected mice. Yet the hybrid virus was still less deadly than the original Wuhan variant of the virus, which killed 100% of infected lab mice.
Scientists at Boston University's National Emerging Infectious Diseases Laboratories (NEIDL) created the chimeric virus to study how omicron versions of the virus, which first appeared in 2021, evade immunity built up against past strains and yet cause a lower rate of severe infections. After exposing mice either to the chimeric virus or to the naturally-occuring omicron BA.1 virus, the researchers found that the mutated spike protein of the omicron virus did enable it to dodge immunity, but that the mutated spike wasn't responsible for making omicron less severe.