Nv. Pavlovich et al., PREPARATION OF FRANCISELLA-TULARENSIS NONCAPSULAR VARIANTS, Zurnal mikrobiologii, epidemiologii i immunobiologii, (2), 1993, pp. 7-11
New methods (selection in medium T with 20% Tween-80, inducing mutatio
ns leading to the appearance of resistance to triphenyl tetrazolium ch
loride or indoxyl phosphate) helped create a collection of F. tularens
is stable noncapsular variants from strains of different subspecies. T
he characteristic features of all F. tularensis cap- variants include
inability to serologic tests with erythrocytic diagnosticums, the abse
nce of capsular antigens, sensitivity to normal human serum.