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Disruption of the SapM locus in Mycobacterium bovis BCG improves its protective efficacy as a vaccine against M. tuberculosis.

Festjens N, Bogaert P, Batni A, Houthuys E, Plets E, Vanderschaeghe D, Laukens B, Asselbergh B, Parthoens E, De Rycke R, Willart MA, Jacques P, Elewaut D, Brouckaert P, Lambrecht BN, Huygen K, Callewaert N - EMBO Mol Med (2011)

Bottom Line: We studied the vaccine potential of BCG mutants deficient in the secreted acid phosphatase, SapM, or in the capping of the immunomodulatory ManLAM cell wall component with α-1,2-oligomannoside.Persistence of the SapM-mutated BCG in vivo resembled that of the parental BCG indicating that this mutation will likely not compromise the safety of the BCG vaccine.The SapM mutant BCG vaccine was more effective than the parental vaccine in inducing recruitment and activation of CD11c(+) MHC-II(int) CD40(int) dendritic cells (DCs) to the draining lymph nodes.

View Article: PubMed Central - PubMed

Affiliation: Unit for Medical Biotechnology, Department for Molecular Biomedical Research, Ghent, Belgium. nele.festjens@dmbr.vib-ugent.be

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Bacterial replication of M. bovis BCG WT versus SapM mutant in spleen and lungs of mice and immune response in the lungs following infectionA,B. BALB/c mice were intravenously infected with M. bovis BCG WT or with SapM mutant and sacrificed after 2 weeks (black bars), 4 weeks (dark grey bars) or 12 weeks (light grey bars; 5 mice/group). Lung and spleen homogenates were plated in duplicates on 7H10 agar for counting CFUs. The mean and standard errors (SEM) of each group are shown. No difference was detected between the SapM mutant and the WT (p > 0.1, Mann–Whitney U-test).C. C57BL/6 mice were infected intratracheally with M. bovis BCG WT or with SapM mutant. After 4 weeks, five mice/group were killed and BAL was performed. The mean levels of TNF and IFN-γ in the BALF and SEM of each group are representative of two independent experiments. (p > 0.05, Mann–Whitney U-test).D. C57BL/6 mice were infected intravenously with M. bovis BCG WT or with mutants. After 3 weeks, five mice/group were killed and livers were removed aseptically. Quantitative studies on H&E-stained paraffin sections to identify and count granuloma were performed by direct microscopic examination (3.5× magnification) and analysed with ImageJ software. The SEM of each group are shown.
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fig02: Bacterial replication of M. bovis BCG WT versus SapM mutant in spleen and lungs of mice and immune response in the lungs following infectionA,B. BALB/c mice were intravenously infected with M. bovis BCG WT or with SapM mutant and sacrificed after 2 weeks (black bars), 4 weeks (dark grey bars) or 12 weeks (light grey bars; 5 mice/group). Lung and spleen homogenates were plated in duplicates on 7H10 agar for counting CFUs. The mean and standard errors (SEM) of each group are shown. No difference was detected between the SapM mutant and the WT (p > 0.1, Mann–Whitney U-test).C. C57BL/6 mice were infected intratracheally with M. bovis BCG WT or with SapM mutant. After 4 weeks, five mice/group were killed and BAL was performed. The mean levels of TNF and IFN-γ in the BALF and SEM of each group are representative of two independent experiments. (p > 0.05, Mann–Whitney U-test).D. C57BL/6 mice were infected intravenously with M. bovis BCG WT or with mutants. After 3 weeks, five mice/group were killed and livers were removed aseptically. Quantitative studies on H&E-stained paraffin sections to identify and count granuloma were performed by direct microscopic examination (3.5× magnification) and analysed with ImageJ software. The SEM of each group are shown.

Mentions: To evaluate the safety of the mutant BCG strains, we tested them for parameters related to chronic mycobacterial infection. To analyse bacterial persistence in vivo, BALB/c mice were infected intravenously with M. bovis BCG or M. bovis BCG mutants (Mb2203, Mb1661c or SapM). The bacterial load in the lungs and spleen was determined 2, 4, and 12 weeks post-infection. Two weeks after infection, the load of the parental strain in the lung was slightly higher than the loads of the mutants. Four weeks post-infection, the mutants reached similar numbers of CFU in the lungs and spleen as the WT M. bovis BCG (Fig 2A and B, Suppl. Fig 2A and B). Overall, bacterial numbers in lung and spleen decreased over time, indicating partial clearance.


Disruption of the SapM locus in Mycobacterium bovis BCG improves its protective efficacy as a vaccine against M. tuberculosis.

Festjens N, Bogaert P, Batni A, Houthuys E, Plets E, Vanderschaeghe D, Laukens B, Asselbergh B, Parthoens E, De Rycke R, Willart MA, Jacques P, Elewaut D, Brouckaert P, Lambrecht BN, Huygen K, Callewaert N - EMBO Mol Med (2011)

Bacterial replication of M. bovis BCG WT versus SapM mutant in spleen and lungs of mice and immune response in the lungs following infectionA,B. BALB/c mice were intravenously infected with M. bovis BCG WT or with SapM mutant and sacrificed after 2 weeks (black bars), 4 weeks (dark grey bars) or 12 weeks (light grey bars; 5 mice/group). Lung and spleen homogenates were plated in duplicates on 7H10 agar for counting CFUs. The mean and standard errors (SEM) of each group are shown. No difference was detected between the SapM mutant and the WT (p > 0.1, Mann–Whitney U-test).C. C57BL/6 mice were infected intratracheally with M. bovis BCG WT or with SapM mutant. After 4 weeks, five mice/group were killed and BAL was performed. The mean levels of TNF and IFN-γ in the BALF and SEM of each group are representative of two independent experiments. (p > 0.05, Mann–Whitney U-test).D. C57BL/6 mice were infected intravenously with M. bovis BCG WT or with mutants. After 3 weeks, five mice/group were killed and livers were removed aseptically. Quantitative studies on H&E-stained paraffin sections to identify and count granuloma were performed by direct microscopic examination (3.5× magnification) and analysed with ImageJ software. The SEM of each group are shown.
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Related In: Results  -  Collection

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fig02: Bacterial replication of M. bovis BCG WT versus SapM mutant in spleen and lungs of mice and immune response in the lungs following infectionA,B. BALB/c mice were intravenously infected with M. bovis BCG WT or with SapM mutant and sacrificed after 2 weeks (black bars), 4 weeks (dark grey bars) or 12 weeks (light grey bars; 5 mice/group). Lung and spleen homogenates were plated in duplicates on 7H10 agar for counting CFUs. The mean and standard errors (SEM) of each group are shown. No difference was detected between the SapM mutant and the WT (p > 0.1, Mann–Whitney U-test).C. C57BL/6 mice were infected intratracheally with M. bovis BCG WT or with SapM mutant. After 4 weeks, five mice/group were killed and BAL was performed. The mean levels of TNF and IFN-γ in the BALF and SEM of each group are representative of two independent experiments. (p > 0.05, Mann–Whitney U-test).D. C57BL/6 mice were infected intravenously with M. bovis BCG WT or with mutants. After 3 weeks, five mice/group were killed and livers were removed aseptically. Quantitative studies on H&E-stained paraffin sections to identify and count granuloma were performed by direct microscopic examination (3.5× magnification) and analysed with ImageJ software. The SEM of each group are shown.
Mentions: To evaluate the safety of the mutant BCG strains, we tested them for parameters related to chronic mycobacterial infection. To analyse bacterial persistence in vivo, BALB/c mice were infected intravenously with M. bovis BCG or M. bovis BCG mutants (Mb2203, Mb1661c or SapM). The bacterial load in the lungs and spleen was determined 2, 4, and 12 weeks post-infection. Two weeks after infection, the load of the parental strain in the lung was slightly higher than the loads of the mutants. Four weeks post-infection, the mutants reached similar numbers of CFU in the lungs and spleen as the WT M. bovis BCG (Fig 2A and B, Suppl. Fig 2A and B). Overall, bacterial numbers in lung and spleen decreased over time, indicating partial clearance.

Bottom Line: We studied the vaccine potential of BCG mutants deficient in the secreted acid phosphatase, SapM, or in the capping of the immunomodulatory ManLAM cell wall component with α-1,2-oligomannoside.Persistence of the SapM-mutated BCG in vivo resembled that of the parental BCG indicating that this mutation will likely not compromise the safety of the BCG vaccine.The SapM mutant BCG vaccine was more effective than the parental vaccine in inducing recruitment and activation of CD11c(+) MHC-II(int) CD40(int) dendritic cells (DCs) to the draining lymph nodes.

View Article: PubMed Central - PubMed

Affiliation: Unit for Medical Biotechnology, Department for Molecular Biomedical Research, Ghent, Belgium. nele.festjens@dmbr.vib-ugent.be

Show MeSH
Related in: MedlinePlus