Natural Spillovers Over Pre-Adaptation, UCSD Study Finds
UC San Diego researchers analyzed genomes from influenza A, Ebola, Marburg, mpox, SARS-CoV and SARS-CoV-2 and found that most zoonotic viruses do not show adaptive evolution before jumping to humans; SARS-CoV-2 shows no lab-adaptation signal, consistent with natural spillover, while the 1977 H1N1 pandemic shows lab-adaptation signatures—together providing a framework to distinguish natural outbreaks from laboratory manipulation and guiding future outbreak surveillance.