Evidence of heterogeneity of lipopolysaccharides among Brucella biovars in relation to A and M specificities.

Sixteen smooth Brucella strains were lysed and digested by proteinase K, and the LPS fractions analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Two profiles were distinguished after periodic acid oxidation and silver staining. The first, present in biovars A greater than M, was a close succession of regularly spaced narrow bands; the second, present in biovars M greater than A, showed regularly spaced doublets separated by a barely visible band (B. abortus = A, melitensis = M).