Preliminary findings for an inactivated African horsesickness vaccine using binary ethyleneimine

Investigation studies on inactivated African horsesickness vaccine using binary ethyleneimine were conducted. The inactivation process of virulent type-9 strain using the above inactivant revealed complete virus inactivation at 18, 48 and 84 h post-treatment with inactivant concentrations of 0.004, 0.003 and 0.002M, respectively, without detection of residual virus. An inactivant concentration of 0.003M is recommended and no changes in viral antigenic properties were noticed in complement fixation test. The physical parameters in oil-emulsion vaccine using the incomplete Freund's adjuvant, were studied. Emulsification time of 25 s was recommended which resulted in a 100% emulsion phase, creamy consistency, flow time of 2.2 s/0.1 ml and a stability at 4 degrees C and 37 degrees C for six months and 15 days, respectively. An experimental application of the oil vaccine in two horses (which was followed by a booster oil vaccine inoculation at 2 months post-vaccination) gave an acceptable immunity during the 6-month observation period with a maximum decline of the neutralizing antibody titer of 0.2 log10 at end of this period. Challenge of the vaccinated horses with the virulent virus strain at 2 months post-vaccination did not bring about any clinical symptoms.