RESUMEN
In this study, we characterized the role of Rv2617c in the virulence of Mycobacterium tuberculosis. Rv2617c is a protein of unknown function unique to M. tuberculosis complex (MTC) and Mycobacterium leprae. In vitro, this protein interacts with the virulence factor P36 (also named Erp) and KdpF, a protein linked to nitrosative stress. Here, we showed that knockout of the Rv2617c gene in M. tuberculosis CDC1551 reduced the replication of the pathogen in a mouse model of infection and favored the trafficking of mycobacteria to phagolysosomes. We also demonstrated that Rv2617c and P36 are required for resistance to in vitro hydrogen peroxide treatment in M. tuberculosis and Mycobacterium bovis, respectively. These findings indicate Rv2617c and P36 act in concert to prevent bacterial damage upon oxidative stress.
Asunto(s)
Proteínas Bacterianas/genética , Mycobacterium bovis/genética , Mycobacterium bovis/patogenicidad , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/patogenicidad , Estrés Oxidativo , Factores de Virulencia/genética , Animales , Pulmón/microbiología , Macrófagos/microbiología , Ratones , Ratones Endogámicos BALB C , VirulenciaRESUMEN
Mycobacterium bovis is the causative agent of bovine tuberculosis and is a member of Mycobacterium tuberculosis complex, which causes tuberculosis in a number of mammals including humans. Previous studies have shown that the genes encoding the two-component system PhoPR, which regulates several genes involved in the virulence of M. tuberculosis, are polymorphic in M. bovis, when compared to M. tuberculosis, which results in a dysfunctional two-component system. In this study we investigated the role of PhoPR in two M. bovis strains with differing degrees of virulence. We found that the deletion of phoP in an M. bovis isolate reduced its capacity of inducing phagosomal arrest in bovine macrophages. By gene expression analysis, we demonstrated that, in both M. bovis strains, PhoP regulates the expression of a putative lipid desaturase Mb1404-Mb1405, a protein involved in redox stress AhpC, the sulfolipid transporter Mmpl8 and the secreted antigen ESAT-6. Furthermore, the lack of PhoP increased the sensitivity to acidic stress and alteration of the biofilm/pellicle formation of M. bovis. Both these phenotypes are connected to bacterial redox homeostasis. Therefore, the results of this study suggest a role of PhoPR in M. bovis to be linked to the mechanisms that mycobacteria display to maintain their redox balance.
Asunto(s)
Proteínas Bacterianas/genética , Regulación Bacteriana de la Expresión Génica , Mycobacterium bovis/genética , Animales , Biopelículas/crecimiento & desarrollo , Bovinos , Homeostasis/genética , Humanos , Macrófagos/microbiología , Mycobacterium bovis/patogenicidad , Mycobacterium tuberculosis/genética , Oxidación-Reducción , Fenotipo , Estrés Fisiológico/genética , Tuberculosis Bovina , Virulencia/genéticaRESUMEN
In this study, a Mycobacterium bovis knockout strain in phoP-phoR and mce2 operons was tested as an antituberculosis experimental vaccine in animal models. The double mutant strain was significantly more attenuated than the wild type strain in inmunocompetent and inmunodeficient mice. Vaccination with the double mutant protected mice against challenge with a virulent M. bovis strain.