Inactivated African horse sickness virus cell culture vaccine.

Immunogenic killed vaccine against African Horse Sickness can ce prepared from a neurotropic vaccine strain or a virulent strain of virus, type 9, grown in a monkey kidney stable cell line. Virus was inactiv:ttd with either formaldehyde in a final concentration of 1 :8000 or j3-propiolactone at 0.2 per cent. In order to enhance the immunogenicty of the product, aluminium hydroxide was added to the vaccine as an adjuvant. After inoculation of a single dme of either vaccine, neutralizing antibodies developed within 4 wee~(s, and ail horses resistd challenge with homologous virulent virus. When two in;e:tions of inactivated vaccine were administered at an interval of 4 weeks, much higher neutralizing antibodies were preœnt in sera and 6 months later al! hor~es were still resistant to a challenge dose of virulent virus. Under the conditions of these experiments a significantly higher degree of antigenicity was demonstrated with form:tlin-inactivatd vaccine than with j3-propiolactone-inactivated vaccine.