frazer convinced zhou to join him at the university of queensland, brisbane, and in 1990 they began to use molecular biology to synthesize particles in vitro that could mimic the virus. in march 1991 zhou's wife and fellow researcher, xiao-yi sun, assembled by zhou's instructions two proteins into a virus-like particle (vlp), resembling the hpv shell, from which hpv vaccine would ultimately be made.