Background: Rift Valley Fever (RVF) is a mosquito-borne viral zoonotic disease that is endemic in
Africa and the Arabian Peninsula. Outbreaks of RVF resulted in severe losses to the animal industry
and major threats to the public health. Control of RVF in Egypt is dependent on vector control and
yearly vaccination of livestock using an aluminum hydroxide gel-adjuvanted inactivated Rift Valley
fever virus (RVFV) vaccine.
Objective: Herein, we aimed to enhance the immunogenicity of the conventional vaccine by
developing a smaller particle size vaccine formulation through ultrasonic dispersion of aluminum
Methods: This was achieved by ultrasonication of aluminum hydroxide gel in the presence of
trehalose as dispersant and measuring different physical characters including particle size, Zeta
potential, loading capacity and imaging of adjuvant before and after formulation.
Results: Ultrasonication of aluminum hydroxide gel resulted in generation of 120-200 nm gel
structures followed by vaccine formulation showed enhancement of vaccine loading capacity. Animals
vaccinated using the enhanced formula were completely protected against RVF challenge virus and
produced higher RVFV neutralizing antibody titers.
Conclusion: The vaccine developed based on small particle vaccine formulation is an economic
solution that can be added inline to existing production platforms to enhance immunogenicity.