Biodistribution of viable vs. non viable 35S labeled bacteria. As a mode to compare the localization of labeled bacteria, metabolic labeling was performed for F. tularensis subsp. novicida. The data represent an average of 3 mice per treatment and are expressed as cpm/g. Viable (unfixed) labeled F. tularensis subsp. novicida is found mainly in the lungs while there was an increase in non-viable (fixed) organisms localizing primarily to the gall bladder.