INACTIVATED VIRAL VACCINES
Although the initial results with inactivated vaccine were negative with high doses of formalin treatment (loss of antigenicity of the viral envelope proteins), it was quickly discovered that by using low doses of formalin, the antigenicity of the envelope proteins was preserved. This preparation was capable of inducing viral neutralizing antibodies in both mice and nonhuman primates. This area is presently being actively pursued, but the problem will be overcoming the rapidly changing antigens of the wild-type virus