Marine sponge microbe provides insights into evolution of tuberculosis

Amazing stuff!

"The surprising discovery of a bacterium in a marine sponge from the Great Barrier Reef with striking similarity to Mycobacterium tuberculosis, the pathogen responsible for tuberculosis (TB), could unlock and inform future TB research and treatment strategies. ...

However, the researchers found that, unlike M. tuberculosis, M. spongiae does not cause disease in mice, making it non-virulent. ..."

From the abstract:

"Reconstructing the evolutionary origins of Mycobacterium tuberculosis, the causative agent of human tuberculosis, has helped identify bacterial factors that have led to the tubercle bacillus becoming such a formidable human pathogen. Here we report the discovery and detailed characterization of an exceedingly slow growing mycobacterium that is closely related to M. tuberculosis for which we have proposed the species name Mycobacterium spongiae sp. nov., (strain ID: FSD4b-SM). The bacterium was isolated from a marine sponge, taken from the waters of the Great Barrier Reef in Queensland, Australia. Comparative genomics revealed that, after the opportunistic human pathogen Mycobacterium decipiens, M. spongiae is the most closely related species to the M. tuberculosis complex reported to date, with 80% shared average nucleotide identity and extensive conservation of key M. tuberculosis virulence factors, including intact ESX secretion systems and associated effectors. Proteomic and lipidomic analyses showed that these conserved systems are functional in FSD4b-SM, but that it also produces cell wall lipids not previously reported in mycobacteria. We investigated the virulence potential of FSD4b-SM in mice and found that, while the bacteria persist in lungs for 56 days after intranasal infection, no overt pathology was detected. The similarities with M. tuberculosis, together with its lack of virulence, motivated us to investigate the potential of FSD4b-SM as a vaccine strain and as a genetic donor of the ESX-1 genetic locus to improve BCG immunogenicity. However, neither of these approaches resulted in superior protection against M. tuberculosis challenge compared to BCG vaccination alone. The discovery of M. spongiae adds to our understanding of the emergence of the M. tuberculosis complex and it will be another useful resource to refine our understanding of the factors that shaped the evolution and pathogenesis of M. tuberculosis."

Marine sponge microbe provides insights into evolution of tb

TB under the sea: A marine sponge microbe provides insights into the evolution of tuberculosis (original news release) "The surprising discovery of a bacterium in a marine sponge from the Great Barrier Reef with striking similarity to Mycobacterium tuberculosis, the pathogen responsible for tuberculosis (TB), could unlock and inform future TB research and treatment strategies."

Marine sponge microbe provides insights into evolution and virulence of the tubercle bacillus (open access)

Mycobacterium spongiae under microscope