[Neuraminidase activity in representatives of the genus Francisella].

In two Francisella species (F. tularensis and F. novicida) neuraminidase activity, heretofore unknown, was detected. The enzyme exhibited specificity with respect to the substrates used in the investigation, neutralizing natural mucins, but not other compounds (glycoproteins and glycoproteins). All F. tularensis strains were found to have enzymatic activity irrespective of their subspecies, but neuraminidase activity was higher in the strains belonging to the American subspecies. Experimentally obtained F. tularensis noncapsular variants possessed higher neuraminidase activity than the capsular parent strains. The conclusion on the possible role of this enzyme in F. tularensis colonization of the host body was made.