Pathogenicity of the subspecies mycoides of Mycoplasma mycoides for cattle, sheep and goats

Abstract

Recent work has shown that strains classified as M. mycoides subsp. mycoides may be separated into 2 types according to their growth rate and their behaviour in certain biochemical tests. The large colony (LC) types, most of which are from goats, are pathogenic for sheep and goats but apparently not for cattle. The small colony (SC) types include the classical contagious bovine pleuropneumonia (CBPP) strains from cattle and four strains from goats. These SC types are potentially pathogenic for cattle, sheep and goats. Strains of M. mycoides subsp. mycoides from CBPP differ in their virulence in cattle. The degree of virulence is correlated with the quantity of galactan produced in cultures of the organism, suggesting an important role for galactan in pathogenicity. This is consistent with the production by galactan of physiological effects in calves and in the enhancement of infection in cattle given galactan at the same time as cultures of the organism. Contagious caprine pleuropneumonia (CCPP) can be produced experimentally in goats using cultures of M. mycoides subsp. capri. Whether the glucan produced in such cultures is a factor in pathogenicity of this organism has not been determined. Hydrogen peroxide demonstrated in tracheal organ cultures of M. mycoides subsp. capri may contribute to its pathogenicity.