Preliminary findings for an inactivated African horsesickness vaccine using binary ethyleneimine.

The research article describes the development of a potential vaccine for African horsesickness using binary ethyleneimine and tests its effectiveness in horses.

Objective and Method

• The researchers were seeking to develop a vaccine for African horsesickness, a highly infectious and deadly virus that affects horses. The disease is caused by orbiviruses and there is currently no effective treatment available.
• To experiment with potential vaccines, the research team used a technique involving binary ethyleneimine, a strong inactivant that has been used in the production of vaccines for other diseases. They applied different concentrations of this inactivant to a virulent strain of the African horsesickness virus (type-9 strain) and monitored the inactivation process — the time it took for the virus to be completely neutralized.

Observations and Results

• The process of inactivating the virus was successful at different time points and concentrations: complete virus inactivation was observed at 18 hours with a 0.004M inactivant concentration, 48 hours with a 0.003M concentration, and 84 hours with a 0.002M concentration.
• The researchers recommend a concentration of 0.003M. Importantly, they detected no residual virus and no changes in the virus’s antigenic properties during the process, which is a positive sign for the potential use of this method in vaccine production.

Physical Parameters and Vaccine Application

• The team then studied the physical parameters of an oil-emulsion vaccine created using the inactivated virus and an incomplete Freund’s adjuvant — a substance used to enhance the body’s immune response to the vaccine.
• They found that an emulsification time of 25 seconds resulted in a 100% emulsion phase, a creamy consistency, and a flow rate of 2.2 seconds per 0.1 ml. The vaccine showed a stability of six months at 4 degrees Celsius and 15 days at 37 degrees Celsius.

Experimental Application and Immunity

• An experimental application of the vaccine was performed on two horses, followed by a booster dose two months post-vaccination.
• The horses showed an acceptable immune response, with the neutralizing antibody titer (the concentration of antibodies in the blood that can neutralize a virus) declining by just 0.2 log10 over a six-month observation period.
• When the vaccinated horses were challenged with the virulent virus strain two months post-vaccination, they displayed no clinical symptoms, suggesting that the vaccine was effective in preventing disease.