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Vaccination with an Attenuated Ferritin Mutant Protects Mice against Virulent Mycobacterium tuberculosis.

Subbian S, Pandey R, Soteropoulos P, Rodriguez GM - J Immunol Res (2015)

Bottom Line: The results show that the protection elicited by immunization with the bfrB mutant is comparable to BCG vaccination with respect to reduction of bacterial burden.However, significant distinctions in the disease pathology and host genome-wide lung transcriptome suggest improved containment of Mtb infection in animals vaccinated with the bfrB mutant, compared to BCG.We found that downmodulation of inflammatory response and enhanced fibrosis, compared to BCG vaccination, is associated with the protective response elicited by the bfrB mutant.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Mycobacterial Immunity and Pathogenesis, Rutgers, The State University of New Jersey, 225 Warren Street, Newark, NJ 07103, USA.

ABSTRACT
Mycobacterium tuberculosis the causative agent of tuberculosis affects millions of people worldwide. New tools for treatment and prevention of tuberculosis are urgently needed. We previously showed that a ferritin (bfrB) mutant of M. tuberculosis has altered iron homeostasis and increased sensitivity to antibiotics and to microbicidal effectors produced by activated macrophages. Most importantly, M. tuberculosis lacking BfrB is strongly attenuated in mice, especially, during the chronic phase of infection. In this study, we examined whether immunization with a bfrB mutant could confer protection against subsequent infection with virulent M. tuberculosis in a mouse model. The results show that the protection elicited by immunization with the bfrB mutant is comparable to BCG vaccination with respect to reduction of bacterial burden. However, significant distinctions in the disease pathology and host genome-wide lung transcriptome suggest improved containment of Mtb infection in animals vaccinated with the bfrB mutant, compared to BCG. We found that downmodulation of inflammatory response and enhanced fibrosis, compared to BCG vaccination, is associated with the protective response elicited by the bfrB mutant.

No MeSH data available.


Related in: MedlinePlus

Experimental design, lung bacillary burden, and gross pathology of vaccinated and uninfected or Mtb-infected mice. (a) Schema of the mice vaccination schedule and Mtb infection experiment. (b) Lung bacillary load in mice infected with virulent Mtb H37Rv after vaccination with PBS (sham) or BCG or ΔbfrB for 4 (∗P = 0.033) or 8 weeks (∗∗P = 0.035). Gross lung pathology of vaccinated and uninfected or Mtb-infected-mice. (c) H&E stained lung section of BCG vaccinated (for 8 weeks) and uninfected mice. (d) H&E stained lung section of ΔbfrB vaccinated (for 8 weeks) and uninfected mice. (e) H&E stained lung section of BCG vaccinated (for 8 weeks) and Mtb-infected (for 4 weeks) mice. The arrows in (e) show a multifocal, coalescent granuloma. (f) H&E stained lung section of ΔbfrB vaccinated (for 8 weeks) and Mtb-infected (for 4 weeks) mice. The arrows in (f) show multiple, small granulomas.
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fig1: Experimental design, lung bacillary burden, and gross pathology of vaccinated and uninfected or Mtb-infected mice. (a) Schema of the mice vaccination schedule and Mtb infection experiment. (b) Lung bacillary load in mice infected with virulent Mtb H37Rv after vaccination with PBS (sham) or BCG or ΔbfrB for 4 (∗P = 0.033) or 8 weeks (∗∗P = 0.035). Gross lung pathology of vaccinated and uninfected or Mtb-infected-mice. (c) H&E stained lung section of BCG vaccinated (for 8 weeks) and uninfected mice. (d) H&E stained lung section of ΔbfrB vaccinated (for 8 weeks) and uninfected mice. (e) H&E stained lung section of BCG vaccinated (for 8 weeks) and Mtb-infected (for 4 weeks) mice. The arrows in (e) show a multifocal, coalescent granuloma. (f) H&E stained lung section of ΔbfrB vaccinated (for 8 weeks) and Mtb-infected (for 4 weeks) mice. The arrows in (f) show multiple, small granulomas.

Mentions: We have shown previously that, after aerosol exposure, ΔbfrB replicates in the mice lungs during the first 4 weeks of infection but is unable to persist and establish a chronic infection. We postulated that the inability of ΔbfrB to persist in the infected mice lungs was due to the effects of the adaptive immune response and hypothesized that the transient replication of ΔbfrB might stimulate an immune response that could protect against subsequent infection with a fully virulent Mtb. To test this, groups of mice (n = 5) were vaccinated with a single dose of ΔbfrB or the standard BCG vaccine and at four or eight weeks postvaccination a group of mice were sacrificed to determine CFUs of each vaccine strain in the lungs whereas a second group of mice were challenged via aerosol infection with virulent wild type H37Rv (Figure 1(a)). Enumeration of lung CFUs from vaccinated, uninfected mice lungs show that at the high dose used for subcutaneous administration the attenuation of ΔbfrB and BCG was comparable (Supplementary Figure  1). Among the Mtb-infected mice, those vaccinated with ΔbfrB or BCG had significantly less number of bacilli in their lungs and spleen, compared to the sham (PBS-)vaccinated controls (Figure 1(b) and Supplementary Figure  2). A further reduction in bacillary load was observed in ΔbfrB compared to the BCG in the 8 weeks vaccinated, Mtb-infected mice lungs, though this difference was not statistically significant (P = 0.63). Thus, we conclude that ΔbfrB vaccinated mice controlled bacterial multiplication in the lungs to a similar extent as the BGC vaccinated mice. Since there was no significant difference in the level of protection between animals vaccinated for 4 or 8 weeks prior to challenge, we decided to focus on the longer lasting response of animals vaccinated for 8 weeks before infection, for subsequent analyses.


Vaccination with an Attenuated Ferritin Mutant Protects Mice against Virulent Mycobacterium tuberculosis.

Subbian S, Pandey R, Soteropoulos P, Rodriguez GM - J Immunol Res (2015)

Experimental design, lung bacillary burden, and gross pathology of vaccinated and uninfected or Mtb-infected mice. (a) Schema of the mice vaccination schedule and Mtb infection experiment. (b) Lung bacillary load in mice infected with virulent Mtb H37Rv after vaccination with PBS (sham) or BCG or ΔbfrB for 4 (∗P = 0.033) or 8 weeks (∗∗P = 0.035). Gross lung pathology of vaccinated and uninfected or Mtb-infected-mice. (c) H&E stained lung section of BCG vaccinated (for 8 weeks) and uninfected mice. (d) H&E stained lung section of ΔbfrB vaccinated (for 8 weeks) and uninfected mice. (e) H&E stained lung section of BCG vaccinated (for 8 weeks) and Mtb-infected (for 4 weeks) mice. The arrows in (e) show a multifocal, coalescent granuloma. (f) H&E stained lung section of ΔbfrB vaccinated (for 8 weeks) and Mtb-infected (for 4 weeks) mice. The arrows in (f) show multiple, small granulomas.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig1: Experimental design, lung bacillary burden, and gross pathology of vaccinated and uninfected or Mtb-infected mice. (a) Schema of the mice vaccination schedule and Mtb infection experiment. (b) Lung bacillary load in mice infected with virulent Mtb H37Rv after vaccination with PBS (sham) or BCG or ΔbfrB for 4 (∗P = 0.033) or 8 weeks (∗∗P = 0.035). Gross lung pathology of vaccinated and uninfected or Mtb-infected-mice. (c) H&E stained lung section of BCG vaccinated (for 8 weeks) and uninfected mice. (d) H&E stained lung section of ΔbfrB vaccinated (for 8 weeks) and uninfected mice. (e) H&E stained lung section of BCG vaccinated (for 8 weeks) and Mtb-infected (for 4 weeks) mice. The arrows in (e) show a multifocal, coalescent granuloma. (f) H&E stained lung section of ΔbfrB vaccinated (for 8 weeks) and Mtb-infected (for 4 weeks) mice. The arrows in (f) show multiple, small granulomas.
Mentions: We have shown previously that, after aerosol exposure, ΔbfrB replicates in the mice lungs during the first 4 weeks of infection but is unable to persist and establish a chronic infection. We postulated that the inability of ΔbfrB to persist in the infected mice lungs was due to the effects of the adaptive immune response and hypothesized that the transient replication of ΔbfrB might stimulate an immune response that could protect against subsequent infection with a fully virulent Mtb. To test this, groups of mice (n = 5) were vaccinated with a single dose of ΔbfrB or the standard BCG vaccine and at four or eight weeks postvaccination a group of mice were sacrificed to determine CFUs of each vaccine strain in the lungs whereas a second group of mice were challenged via aerosol infection with virulent wild type H37Rv (Figure 1(a)). Enumeration of lung CFUs from vaccinated, uninfected mice lungs show that at the high dose used for subcutaneous administration the attenuation of ΔbfrB and BCG was comparable (Supplementary Figure  1). Among the Mtb-infected mice, those vaccinated with ΔbfrB or BCG had significantly less number of bacilli in their lungs and spleen, compared to the sham (PBS-)vaccinated controls (Figure 1(b) and Supplementary Figure  2). A further reduction in bacillary load was observed in ΔbfrB compared to the BCG in the 8 weeks vaccinated, Mtb-infected mice lungs, though this difference was not statistically significant (P = 0.63). Thus, we conclude that ΔbfrB vaccinated mice controlled bacterial multiplication in the lungs to a similar extent as the BGC vaccinated mice. Since there was no significant difference in the level of protection between animals vaccinated for 4 or 8 weeks prior to challenge, we decided to focus on the longer lasting response of animals vaccinated for 8 weeks before infection, for subsequent analyses.

Bottom Line: The results show that the protection elicited by immunization with the bfrB mutant is comparable to BCG vaccination with respect to reduction of bacterial burden.However, significant distinctions in the disease pathology and host genome-wide lung transcriptome suggest improved containment of Mtb infection in animals vaccinated with the bfrB mutant, compared to BCG.We found that downmodulation of inflammatory response and enhanced fibrosis, compared to BCG vaccination, is associated with the protective response elicited by the bfrB mutant.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Mycobacterial Immunity and Pathogenesis, Rutgers, The State University of New Jersey, 225 Warren Street, Newark, NJ 07103, USA.

ABSTRACT
Mycobacterium tuberculosis the causative agent of tuberculosis affects millions of people worldwide. New tools for treatment and prevention of tuberculosis are urgently needed. We previously showed that a ferritin (bfrB) mutant of M. tuberculosis has altered iron homeostasis and increased sensitivity to antibiotics and to microbicidal effectors produced by activated macrophages. Most importantly, M. tuberculosis lacking BfrB is strongly attenuated in mice, especially, during the chronic phase of infection. In this study, we examined whether immunization with a bfrB mutant could confer protection against subsequent infection with virulent M. tuberculosis in a mouse model. The results show that the protection elicited by immunization with the bfrB mutant is comparable to BCG vaccination with respect to reduction of bacterial burden. However, significant distinctions in the disease pathology and host genome-wide lung transcriptome suggest improved containment of Mtb infection in animals vaccinated with the bfrB mutant, compared to BCG. We found that downmodulation of inflammatory response and enhanced fibrosis, compared to BCG vaccination, is associated with the protective response elicited by the bfrB mutant.

No MeSH data available.


Related in: MedlinePlus