[Purification and SDS-page analysis of axial filaments from leptospires]

A modified method, differential centrifugation followed by sucrose density centrifugation, was used to purify axial filaments from three strains of Leptospires. Ultrastructure of the axial filaments was studied and profiles of the axial filaments were characterized and compared. The results have shown that all the three strains of Leptospires, i.e., L. interrogsans serovar Lai strain 017, L. biflexa serovar patoc strain Patoc I and L. illini strain 3055, have two axial filaments in one cell. The axial filament is 20 nm in diameter. It is the first observation that the end which inserts the cytoplasms cylinder is wider in diameter than the free one. An insertion pore structure is observed. The new method yields 1.5mg axial filaments from 12 g leptospires cells. SDS-PAGE was first employed in the analysis of axial filaments of leptospires. The results have also shown that there are 6 proteins in the axial filaments of strain 017, MW 26,000-50,000 while 7 proteins in the axial filaments of strain Patoc I and strain 3055. MW 29,000-80,000 and 28,500-80,000 respectively. Interestingly, all the axial filaments of the three strains have a common protein band of MW 31,500. The possibility of using axial filament proteins as a new criterion for typing and a serodiagnosis antigen is discussed.