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Background: Mycolactone, the macrolide exotoxin produced by Mycobacterium ulcerans, causes extensive tissue destruction by inducing apoptosis of host cells. In this study, we aimed at the production of antibodies that could neutralize the cytotoxic activities of mycolactone. Methodology/Principal Findings: Using the B cell hybridoma technology, we generated a series of monoclonal antibodies with specificity for mycolactone from spleen cells of mice immunized with the protein conjugate of a truncated synthetic mycolactone derivative. L929 fibroblasts were used as a model system to investigate whether these antibodies can inhibit the biological effects of mycolactone. By measuring the metabolic activity of the fibroblasts, we found that anti-mycolactone mAbs can completely neutralize the cytotoxic activity of mycolactone. Conclusions/Significance: The toxin neutralizing capacity of anti-mycolactone mAbs supports the concept of evaluating the macrolide toxin as vaccine target. [ABSTRACT FROM AUTHOR]

At first glance, bacteria that belong to the two genera Streptomyces and Mycobacterium of the phylum Actinobacteria show no sign of similarity. Whereas Streptomyces species are generally classified as spore-forming, filamentous bacteria, species of the Mycobacterium genus have been considered non-sporulating, rod-like shaped. However, recent studies in genetics and cell biology of Streptomyces and Mycobacterium have revealed striking analogies in the developmental and morphological hallmarks of their life cycles. Understanding the mechanisms underlying these similarities, as well as variations in morphogenesis and development of these two groups of bacteria may not only provide important insights in the evolution of cell shapes in Actinobacteria, but also lead to medical interventions that impact human health. [Copyright &y& Elsevier]