The story
From Vero cell + toxin. Vero is in turn from Esperanto verda "green" + reno "kidney," as the Vero cell line is derived from kidney cells of the African green monkey.
Etymology from Wiktionary, CC BY-SA 4.0.
verotoxin
Today it means: Any of various toxins produced by some strains of Escherichia coli that are similar to those produced by Shigella. Full definition →