Correlation of bacterial viability with uptake of (14C) acetate into phenolic glycolipid-1 of Mycobacterium leprae within Schwannoma cells

The viability of Mycobacterium leprae, maintained within 33B Schwannoma cells, was estimated in terms of incorporation of (14C) acetate into its specific phenolic glycolipid-1. This measure of viability was correlated with two other assays, viz., fluorescein diacetate/ethidium bromide staining and mouse footpad growth. Observation of a 2-fold increase in the number of intracellular Mycobacterium leprae over an experimental period of 12 days also corroborated this contention. Furthermore, on addition of anti-leprosy drugs to these intracellular Mycobacterium leprae there was significant decrease in phenolic glycolipid-1 synthesis indicative of loss of viability of the organisms. This study also established the importance of the host cell for active bacillary metabolism, as Mycobacterium leprae maintained in cell-free conditions showed no incorporation into phenolic glycolipid-1. Moreover, compromising the host's protein synthesis capacity with cycloheximide, also led to reduction in bacillary metabolism. As this system measures the metabolic synthesis of a unique Mycobacterium leprae component, it would be useful for development and screening of compounds acting against specific bacillary targets. (author). 19 refs., 5 tabs