Overexpression of Adenylyl Cyclase Encoded by the Rv2212 Gene Confers Improved Fitness, Accelerated Recovery from Dormancy and Enhanced Virulence in Mice.

Earlier we demonstrated that the adenylyl cyclase (AC) encoded by the gene plays a key role in the resuscitation and growth of dormant and that overexpression of this gene leads to an increase in intracellular cAMP concentration and prevents the transition of from active growth to dormancy in an extended stationary phase accompanied by medium acidification. We surmised that the homologous gene of (), the main cAMP producer, plays similar physiological roles by supporting, under these conditions, the active state and reactivation of dormant bacteria. To test this hypothesis, we established strain overexpressing and compared its and growth characteristics with a control strain. , the AC-overexpressing pMind strain demonstrated faster growth in a liquid medium, prolonged capacity to form CFUs and a significant delay or even prevention of transition toward dormancy. AC-overexpressing cells exhibited easier recovery from dormancy. , AC-overexpressing bacteria demonstrated significantly higher growth rates (virulence) in the lungs and spleens of infected mice compared to the control strain, and, unlike the latter, killed mice in the TB-resistant strain before month 8 of infection. Even in the absence of selecting hygromycin B, all pMind CFUs retained the insert during growth, strongly suggesting that AC overexpression is beneficial for bacteria. Taken together, our results indicate that cAMP supports the maintenance of cells vitality under unfavorable conditions and their virulence .