Circa 2372, the Vos symbiont -- and Duhan Vos' identity -- was stolen by Verad, with the help of Bethan Roa. Posing as Duhan Vos, Verad ran for and was elected to the Trill Symbiosis Commission. His deception was discovered by Benjamin Sisko and Jadzia Dax, with the help of her sister, Ziranne Idaris. (DS9 short story: "Reflections")