Cell wall glycolipids from Corynebacterium pseudotuberculosis strains with different virulences differ in terms of composition and immune recognition.

Caseous lymphadenitis (CLA) is an infectious disease caused by Corynebacterium pseudotuberculosis in small ruminants and is characterized by the development of granulomas in the lymph nodes, spleen, liver, and lungs. Although little is known about the host-pathogen relationship of this bacterium, it was previously reported that the pathogen's lipids are important for its taxonomic classification and survival inside macrophages. However, there are no studies regarding the composition of these molecules. In this study, cell wall glycolipids from two C. pseudotuberculosis strains presenting different virulence profiles were purified and its composition was characterized. A difference was observed between the electrophoretic and chromatogram profiles for cell wall components from the two strains, mainly among molecules with low molecular weights. IgM from sheep with acute CLA recognized antigens with an estimated molecular weight of 11 kDa of the low-pathogenicity strain, while low-molecular weight antigens from the high-pathogenicity strain presented a lower recognition by these antibodies. Mass spectrometry analysis showed that the cell wall of the high-pathogenicity strain contained glycolipids with high amounts of unsaturated fatty acids and glycerophosphoinositols, which may contribute to the capacity of this strain to cause severe disease. In conclusion, it is indicated that cell wall non-protein antigens can play a key role in C. pseudotuberculosis virulence.