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PhoP: a missing piece in the intricate puzzle of Mycobacterium tuberculosis virulence.

Gonzalo-Asensio J, Mostowy S, Harders-Westerveen J, Huygen K, Hernández-Pando R, Thole J, Behr M, Gicquel B, Martín C - PLoS ONE (2008)

Bottom Line: Inactivation of the transcriptional regulator PhoP results in Mycobacterium tuberculosis attenuation.Preclinical testing has shown that attenuated M. tuberculosis phoP mutants hold promise as safe and effective live vaccine candidates.We focused this study to decipher the virulence networks regulated by PhoP.

View Article: PubMed Central - PubMed

Affiliation: Grupo de Genética de Micobacterias, Departamento de Microbiología, Facultad de Medicina, Universidad de Zaragoza, Zaragoza, Spain.

ABSTRACT
Inactivation of the transcriptional regulator PhoP results in Mycobacterium tuberculosis attenuation. Preclinical testing has shown that attenuated M. tuberculosis phoP mutants hold promise as safe and effective live vaccine candidates. We focused this study to decipher the virulence networks regulated by PhoP. A combined transcriptomic and proteomic analysis revealed that PhoP controls a variety of functions including: hypoxia response through DosR crosstalking, respiratory metabolism, secretion of the major T-cell antigen ESAT-6, stress response, synthesis of pathogenic lipids and the M. tuberculosis persistence through transcriptional regulation of the enzyme isocitrate lyase. We also demonstrate that the M. tuberculosis phoP mutant SO2 exhibits an antigenic capacity similar to that of the BCG vaccine. Finally, we provide evidence that the SO2 mutant persists better in mouse organs than BCG. Altogether, these findings indicate that PhoP orchestrates a variety of functions implicated in M. tuberculosis virulence and persistence, making phoP mutants promising vaccine candidates.

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Related in: MedlinePlus

Hsp65- and Ag85A-specific responses exhibited by mice immunised with M. tuberculosis phoP mutant and BCG.Cells from spleen, lungs and lymph nodes from mice immunised with either BCG or the phoP mutant were stimulated with Hsp65 or Ag85A (p 85) and IFNγ production was measured by ELISA. Bars represent mean and SD from two separate experiments. Asterisks indicate significant differences in IFN-γ production. A higher percentage of Hsp65-specific cells is found in spleen and lymph nodes from mice immunized with SO2 when compared with BCG-immunised mice. Lymph nodes from SO2-immunised mice contained a higher fraction of cell responding to Ag85 in comparison with BCG-immunised mice.
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pone-0003496-g006: Hsp65- and Ag85A-specific responses exhibited by mice immunised with M. tuberculosis phoP mutant and BCG.Cells from spleen, lungs and lymph nodes from mice immunised with either BCG or the phoP mutant were stimulated with Hsp65 or Ag85A (p 85) and IFNγ production was measured by ELISA. Bars represent mean and SD from two separate experiments. Asterisks indicate significant differences in IFN-γ production. A higher percentage of Hsp65-specific cells is found in spleen and lymph nodes from mice immunized with SO2 when compared with BCG-immunised mice. Lymph nodes from SO2-immunised mice contained a higher fraction of cell responding to Ag85 in comparison with BCG-immunised mice.

Mentions: In preclinical studies we have previously shown that the SO2 phoP mutant is more attenuated than BCG and confers protective immunity against tuberculosis in mice and guinea pigs [12]. In order to test whether SO2 was able to elicit antigen-specific responses comparable to the BCG vaccine, BALB/c mice were immunized with both strains and one month after the initial inoculation, Ag85A- and Hsp65-specific responses were measured by ELISA. We observed that even if both strains present similar antigenic capacity, mice immunised with the SO2 phoP mutant exhibit better anti-Hsp65 and anti-Ag85A responses than BCG-vaccinated mice (Figure 6). Additionally, given that a number of vaccine candidates in clinical and preclinical studies are based on Ag85-complex [44], immunity to this antigen is a substantial benefit for the SO2 vaccine candidate. Alternatively, given that persistence in the host could be a potential advantage for a live attenuated vaccine, together with the evidence that ICL is required for chronic persistence of M. tuberculosis in mice [42] led us to study the persistence of the SO2 phoP mutant. BALB/c mice were intravenously inoculated with either BCG or SO2. Both BCG and the phoP mutant could be readily detected in spleen and lungs at 1 month after immunization, but BCG was more rapidly cleared from spleen and particularly from lungs than SO2 after 3 months (Figure 7). The increased persistence exhibited by the SO2 phoP mutant could result in prolonged exposure to the immune system and consequently in long-term immunogenicity.


PhoP: a missing piece in the intricate puzzle of Mycobacterium tuberculosis virulence.

Gonzalo-Asensio J, Mostowy S, Harders-Westerveen J, Huygen K, Hernández-Pando R, Thole J, Behr M, Gicquel B, Martín C - PLoS ONE (2008)

Hsp65- and Ag85A-specific responses exhibited by mice immunised with M. tuberculosis phoP mutant and BCG.Cells from spleen, lungs and lymph nodes from mice immunised with either BCG or the phoP mutant were stimulated with Hsp65 or Ag85A (p 85) and IFNγ production was measured by ELISA. Bars represent mean and SD from two separate experiments. Asterisks indicate significant differences in IFN-γ production. A higher percentage of Hsp65-specific cells is found in spleen and lymph nodes from mice immunized with SO2 when compared with BCG-immunised mice. Lymph nodes from SO2-immunised mice contained a higher fraction of cell responding to Ag85 in comparison with BCG-immunised mice.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2566814&req=5

pone-0003496-g006: Hsp65- and Ag85A-specific responses exhibited by mice immunised with M. tuberculosis phoP mutant and BCG.Cells from spleen, lungs and lymph nodes from mice immunised with either BCG or the phoP mutant were stimulated with Hsp65 or Ag85A (p 85) and IFNγ production was measured by ELISA. Bars represent mean and SD from two separate experiments. Asterisks indicate significant differences in IFN-γ production. A higher percentage of Hsp65-specific cells is found in spleen and lymph nodes from mice immunized with SO2 when compared with BCG-immunised mice. Lymph nodes from SO2-immunised mice contained a higher fraction of cell responding to Ag85 in comparison with BCG-immunised mice.
Mentions: In preclinical studies we have previously shown that the SO2 phoP mutant is more attenuated than BCG and confers protective immunity against tuberculosis in mice and guinea pigs [12]. In order to test whether SO2 was able to elicit antigen-specific responses comparable to the BCG vaccine, BALB/c mice were immunized with both strains and one month after the initial inoculation, Ag85A- and Hsp65-specific responses were measured by ELISA. We observed that even if both strains present similar antigenic capacity, mice immunised with the SO2 phoP mutant exhibit better anti-Hsp65 and anti-Ag85A responses than BCG-vaccinated mice (Figure 6). Additionally, given that a number of vaccine candidates in clinical and preclinical studies are based on Ag85-complex [44], immunity to this antigen is a substantial benefit for the SO2 vaccine candidate. Alternatively, given that persistence in the host could be a potential advantage for a live attenuated vaccine, together with the evidence that ICL is required for chronic persistence of M. tuberculosis in mice [42] led us to study the persistence of the SO2 phoP mutant. BALB/c mice were intravenously inoculated with either BCG or SO2. Both BCG and the phoP mutant could be readily detected in spleen and lungs at 1 month after immunization, but BCG was more rapidly cleared from spleen and particularly from lungs than SO2 after 3 months (Figure 7). The increased persistence exhibited by the SO2 phoP mutant could result in prolonged exposure to the immune system and consequently in long-term immunogenicity.

Bottom Line: Inactivation of the transcriptional regulator PhoP results in Mycobacterium tuberculosis attenuation.Preclinical testing has shown that attenuated M. tuberculosis phoP mutants hold promise as safe and effective live vaccine candidates.We focused this study to decipher the virulence networks regulated by PhoP.

View Article: PubMed Central - PubMed

Affiliation: Grupo de Genética de Micobacterias, Departamento de Microbiología, Facultad de Medicina, Universidad de Zaragoza, Zaragoza, Spain.

ABSTRACT
Inactivation of the transcriptional regulator PhoP results in Mycobacterium tuberculosis attenuation. Preclinical testing has shown that attenuated M. tuberculosis phoP mutants hold promise as safe and effective live vaccine candidates. We focused this study to decipher the virulence networks regulated by PhoP. A combined transcriptomic and proteomic analysis revealed that PhoP controls a variety of functions including: hypoxia response through DosR crosstalking, respiratory metabolism, secretion of the major T-cell antigen ESAT-6, stress response, synthesis of pathogenic lipids and the M. tuberculosis persistence through transcriptional regulation of the enzyme isocitrate lyase. We also demonstrate that the M. tuberculosis phoP mutant SO2 exhibits an antigenic capacity similar to that of the BCG vaccine. Finally, we provide evidence that the SO2 mutant persists better in mouse organs than BCG. Altogether, these findings indicate that PhoP orchestrates a variety of functions implicated in M. tuberculosis virulence and persistence, making phoP mutants promising vaccine candidates.

Show MeSH
Related in: MedlinePlus