This is a randomized , controlled phase I trial , enrolling 60 healthy ( previously vaccinated ) male human volunteers , aged 19-23 years to receive one dose of either Sabin IPV ( 20:32:64 DU/dose ) , adjuvanted Sabin IPV ( 10:16:32 DU/dose ) , or conventional Salk IPV ( 40:8:32 DU/dose ) .