[Characteristics of attenuated immunogenic mutants of shigella flexneri selected from phosphomycin-resistant clones].

Sh. flexneri mutants No. 2a, resistant to phosphomycin (25 microgram/ml), differ in their fermentability in respect to glucose, mannitol, mannose and fructose. The mutants fall into 7 groups by this characteristic. All the resistant mutants, irrespective of the type of hydrocarbon fermentation, have lost their ability of causing keratoconjunctivitis. The decreased virulence of the phosphomycin-resistant mutants is linked with the loss of their penetration properties, although their adhesiveness and proliferative capacity on the surface HeLa cells is retained. A change in the virulence of the mutants under study is not connected with disturbances in the synthesis of O-antigen LPS. Most of these mutants are highly immunogenic.