Mycoplasma capricolum subsp. capripneumoniae, the cause of contagious caprine pleuropneumonia, comprises two distinct biochemical groups

Mycoplasma capricolum subsp. capripneumoniae, the cause of the World Organisation of Animal Health- listed contagious caprine pleuropneumonia, is a member of the Mycoplasma mycoides cluster which comprises five pathogenic mycoplasmas of ruminants. These mycoplasmas are closely related immunologically and genetically which can lead to difficulties for differential diagnosis. The patterns of substrate metabolism of strains of M. c. capripneumoniae, gathered from diverse geographic regions, were studied by measurement of oxygen uptake rates. The strains fell into two major biochemical groups: one which only oxidised organic acids and glycerol and the other which could additionally metabolise sugars. Furthermore when DNA-DNA hybridisation tests were carried out these two groups of strains could be separated by their degree of DNA homology, the mean hybridisation value between members of the two groups was 86% well above the value of 70% normally used to indicate separate species. DNA-DNA hybridisation was also carried out between M. c. capripneumoniae strains and other members of the M. mycoides cluster. These experiments used labelled DNA from two representative subsp. capripneumoniae strains; these were 7/1a (organic acid-oxidising) and 4/2 LC (glucose-oxidising). The results showed a particularly close relationship of the glucose-oxidising strain to M. leachii strains.Keywords: Mycoplasma capricolum subsp. capripneumoniae, Contagious caprine pleuropneumonia, Substrate metabolism, DNA-DNA hybridisation

Mycoplasma capricolum subsp. capripneumoniae, the cause of contagious caprine pleuropneumonia, comprises two distinct biochemical groups

Mycoplasma capricolum subsp. capripneumoniae, the cause of the World Organisation of Animal Health- listed contagious caprine pleuropneumonia, is a member of the Mycoplasma mycoides cluster which comprises five pathogenic mycoplasmas of ruminants. These mycoplasmas are closely related immunologically and genetically which can lead to difficulties for differential diagnosis. The patterns of substrate metabolism of strains of M. c. capripneumoniae, gathered from diverse geographic regions, were studied by measurement of oxygen uptake rates. The strains fell into two major biochemical groups: one which only oxidised organic acids and glycerol and the other which could additionally metabolise sugars. Furthermore when DNA-DNA hybridisation tests were carried out these two groups of strains could be separated by their degree of DNA homology, the mean hybridisation value between members of the two groups was 86% well above the value of 70% normally used to indicate separate species. DNA-DNA hybridisation was also carried out between M. c. capripneumoniae strains and other members of the M. mycoides cluster. These experiments used labelled DNA from two representative subsp. capripneumoniae strains; these were 7/1a (organic acid-oxidising) and 4/2 LC (glucose-oxidising). The results showed a particularly close relationship of the glucose-oxidising strain to M. leachii strains

Genetic and Biochemical Characterization of Glycerol Uptake in Mycoplasma mycoides subsp. mycoides SC: Its Impact on H(2)O(2) Production and Virulence

Highly virulent strains of Mycoplasma mycoides subsp. mycoides SC belonging to the African cluster contain an operon with the genes gtsA, gtsB, and gtsC, encoding membrane ATP binding cassette transporter proteins GtsA, GtsB, and GtsC, which are involved in glycerol transport. Strain Afadé from the African cluster incorporated [U-(14)C]glycerol with a time-dependent increase. The less virulent strain L2 of the European cluster, which lacks gtsB and gtsC, failed to incorporate glycerol. Antibodies against GtsB noncompetitively inhibited glycerol uptake. l-α-Glycerophosphate was not transported by M. mycoides subsp. mycoides SC. It is postulated to be synthesized by phosphorylation of glycerol during transport and subsequently metabolized further to dihydroxyacetone phosphate accompanied by release of H(2)O(2). Peroxide production in glycerol-containing growth medium was high for the African strain Afadé but very low for the European strain L2. Virtually no H(2)O(2) was produced by both strains without glycerol. Hence, the efficient glycerol uptake system found in the virulent strain of the African cluster leads to a strong release of peroxide, a potential virulence factor which is lacking in the less virulent European strains. M. mycoides subsp. mycoides SC might have adopted, as a strategy for virulence, a highly efficient uptake system for glycerol which allows the production of an active metabolic intermediate that damages host cells

Molecular mechanisms of pathogenicity of Mycoplasma mycoides subsp. mycoides SC

Mycoplasma mycoides subsp. mycoides SC, the aetiological agent of contagious bovine pleuropneumonia (CBPP), is considered the most pathogenic of the Mycoplasma species. Its virulence is probably the result of a coordinated action of various components of an antigenically and functionally dynamic surface architecture. The different virulence attributes allow the pathogen to evade the host’s immune defence, adhere tightly to the host cell surface, persist and disseminate in the host causing mycoplasmaemia, efficiently import energetically valuable nutrients present in the environment, and release and simultaneously translocate toxic metabolic pathway products to the host cell where they cause cytotoxic effects that are known to induce inflammatory processes and disease. This strategy enables the mycoplasma to exploit the minimal genetic information in its small genome, not only to fulfil the basic functions for its replication but also to damage host cells in intimate proximity thereby acquiring the necessary bio-molecules, such as amino acids and nucleic acid precursors, for its own biosynthesis and survival