The Reaction of Complement Fixation in Foot-and-Mouth Disease as a means of identifying the Different Types of Virus

Notwithstanding several efforts, a satisfactory method of serological diagnosis of foot-and-mouth disease has not been arrived at. This uncertainty of serological methods delayed the discovery of the plurality of type of the virus, although the observations of epizootics and the irregular results obtained by active and passive immunisation suggested multiplicity of type. Stimulated by such observations, Vallée and Carré (1922) experimented with two viruses of foot-and-mouth disease, one of which was of German and the other of French origin. They were able to show by experimental infection, confirmed by subsequent testing for active immunity, that cases of foot-and-mouth disease with the same clinical course and symptoms could be caused by two distinct types of virus. These they called A (Allemand) and O (Oise). The only difference between these two types was their inability to produce reciprocal immunity. The existence of more than one type of virus has been confirmed in England by Stockman and Minett (1926), and by Bedson, Maitland and Burbury (1927); in Germany, by Waldmann and Trautwein (1926), and Trautwein (1927); in France, by Lebailly (1926), Olitsky (1927), and in Sweden, by Magnusson and Hermansson (1926).