Electron-microscopic evidence for reactions of axial filaments of Leptospira with IgM and IgG antibodies.

Serological identifications of structural components of leptospires have not previously been reported although morphological and antigenic studies have been carried out extensively.The antigenic activity of isolated axial filaments was characterized by direct electron-microscopic visualization of immune precipitates with fractionated antisera. The precipitates were composed of axial filament with IgM or IgG antibodies attached.The axial filament is the first structural component of leptospires to be identified serologically. Knowledge of the pattern of cross-reactivity of this axial filament antigen among various serotypes may be of value in helping to establish a new system of classification based on specific antigens rather than the current system using reciprocal agglutinin-absorption tests, which measures the resultant of many antigens.