STUDIES ON THE KEEPING QUALITY OF BINARY INACTIVATED RIFT VALLEY FEVER VACCINE

In this work, the keeping quality of binary inactivated Rift Valley Fever vaccine was compared with formalin inactivated Rift Valley Fever vaccine using two adjuvants (Alum hydroxide gel and alhydrogel). The prepared vaccines were kept at either room temperature or at 37°C for 4 weeks as well as at +4°C for a longer period up to 12 months. Also, the keeping quality of the vaccine prepared from binary inactivated RVF virus (RVF antigen) which
was kept at -20°C for 18 months was performed. Each batch of vaccine was evaluated, all of them were sterile, safe and potent. The ED50 of RVF virus inactivated by binary and immediately prepared were 0.0004/ml, 0.0006/ml and 0.0007/ml using alum hydroxide gel 50%, Alhydrogel 50% and Alhydrogel 25%, respectively, while that of the inactivated with formalin using alum hydroxide gel was 0.0007/ml. The ED50 of the vaccine inactivated by formalin using alum hydroxide gel and kept at +4°C was within the permissible limit (0.022/ml) after 6 months, while in case of binary inactivated vaccine kept at the same temperature, the ED so was 0.020 after 10 months. The ED so of the vaccines inactivated by binary using 50% or 25% alhydrogel were of the same value when preserved at the same temperature (+4°C) and it was within the permissible limit after 10 months. At room temperature, the ED50 of the vaccine was within the permissible limit after 2 weeks in all batches, while at 37°C it showed a sharp decrease and was higher than the permissible limit from the first week of storage. As regar the vaccine prepared from the RVF antigen which was inactivated by binary and kept at -20°C its ED50 was within the permissible limit.