Oligoadenylate synthetases (OASs) are a family of double-stranded RNA (dsRNA)-activated nucleotidyltransferases involved in pathogen sensing and innate immune response. In this issue of Molecular Cell, Merold et al. define a mechanism of OAS2 activation by dsRNA-length discrimination and its deficiency associated with autoimmune disorder.

A decades-long search culminated in 2013 with the discovery of cGAS – a molecular switch that plays a key role in the human immune system. Carina Baer de Oliveira Mann was a doctoral student with the ...