RESUMEN
Rift Valley Fever virus Vaccine prepared using Binary Ethylen Imine [BEl] as a chemical inactivant was characterized than that prepared using Formalin which has been used for several decades for inactivation of both bacterial and viral antigens. Its inactivation efficacy was of somewhat shorter duration than that of Formalin as inactivant since RVFV infectivity titer was declined in order of 1.8 log [10] / hr post BEl treament and 1.6 log [10] post formalin treatment. The effective potency of BEl. inactivated vaccine was double that of formalin-treated one. This was evident from the dose that protected 50% [ED[50]] of infected mice which was 0.006 for the former and 0.011 for the latter concerning three types of antibodies [H.l. ab, S.N. ab., and PRN. ab.] these types showed about the same fluctuation during the time of the experiment [7 months] while its values were higher post Immunization with BEl inactivated vaccine and long durative than post Formalin inactivated vaccine immunization