[Infectious, immunogenic, and protective characteristics of the Rift Valley fever virus depending on the passage level and storage conditions].

The report discusses the research into the impact of some factors, especially the passage in a suspension of continuous cells BHK-21/13 and storage at different temperatures, upon immunobiological characteristics of the Rift Valley fever (RVF) virus strain 1974-VNIIVViM. The limits for the passage levels and optimal storage conditions providing maximal infectious and immunogenic activity, as well as protection of the attenuated RVF strain 1974- VNIIVViM, were determined. It was found that the RVF virus growth in VHK-21123 cell suspension in the course of 20 consecutive passages and storage at -50 degrees C for 1 to 2 years did not reduce any infectious, immunogenic or protective characteristics of the virus, It was also shown that the RVF virus strain 1974-VNIIVViM could be stored at the following temperature ranges: 1 month at 4 to 6 degrees C, 4 months at -10 to -12 degrees C, 6 months at -20 degrees C, and up to 2 years at -50 degrees C.