[Show abstract][Hide abstract] ABSTRACT: Malaria remains a major global public health problem with an estimated 200 million cases detected in 2012. Although the most advanced candidate malaria vaccine (RTS,S) has shown promise in clinical trials, its modest efficacy and durability have created uncertainty about the impact of RTS,S immunization (when used alone) on global malaria transmission. Here we describe the development and characterization of a novel modified vaccinia virus Ankara (MVA)-based malaria vaccine which co-expresses the Plasmodium yoelii circumsporozoite protein (CSP) and IL-15. Vaccination/challenge studies showed that C57BL/6 mice immunized with the MVA-CSP/IL15 vaccine were protected significantly better against a P. yoelii 17XNL sporozoite challenge than either mice immunized with an MVA vaccine expressing only CSP or naïve controls. Importantly, the levels of total anti-CSP IgG were elevated about 100-fold for the MVA-CSP/IL15 immunized group compared to mice immunized with the MVA-CSP construct that does not express IL-15. Among the IgG subtypes, the IL-15 expressing MVA-CSP vaccine induced levels of IgG1 (8 fold) and IgG2b (80 fold) higher than the MVA-CSP construct. The significantly enhanced humoral responses and protection detected after immunization with the MVA-CSP/IL15 vaccine suggest that this IL-15 expressing MVA construct could be considered in the development of future malaria immunization strategies.
[Show abstract][Hide abstract] ABSTRACT: While formulating Mycobacterium bovis BCG in lipid-based adjuvants has been shown to increase the vaccine's protective immunity, the biological mechanisms responsible for the enhanced potency of lipid encapsulated BCG are unknown. To assess whether mixing BCG in adjuvant increases its immunogenicity by altering post-vaccination organ distribution and persistence, mice were immunized subcutaneously with conventional BCG Pasteur or BCG formulated in DDA/TDB adjuvant and the bio-distribution of BCG bacilli was evaluated in mouse lungs, spleens, lymph nodes, and livers for up to 1 year. Although BCG was rarely detected in mouse livers, mycobacteria were found in mouse lungs, spleens, and lymph nodes for at least 1 year post-vaccination. However, at various time points during the 1 year study, the frequency of lung and spleen infections and the number of mycobacteria in infected organs of individual mice were highly variable. In contrast, mycobacteria were nearly always detected in the lymph nodes of vaccinated mice. While the frequency and extent of lymph node infections generally were not significantly different between mice vaccinated with adjuvanted or nonadjuvanted BCG preparations, multiparameter flow cytometry analysis of lymph node cells showed significantly higher frequencies of CD4+ and CD8+ T cells expressing IFN-γ and IFN-γ/TNF-α in mice immunized with adjuvanted BCG. Overall, our data suggest that the relationship between lymph node infection and the generation of anti-tuberculosis protective responses following BCG vaccination should be further investigated.
[Show abstract][Hide abstract] ABSTRACT: Despite widespread usage of Mycobacterium bovis BCG, the only licensed vaccine against M. tuberculosis (TB), TB remains a global epidemic. To assess whether more direct targeting of the lung mucosa by respiratory immunization would enhance potency and longevity of BCG-induced anti-tuberculosis protective immunity, the long-term impact of intranasal (i.n.) BCG vaccination was compared to conventional subcutaneous (s.c.) immunization using a mouse model of pulmonary tuberculosis. Although significantly improved protection in the lung was seen at early time points (2 and 4 months post-vaccination) for i.n. BCG immunized mice, no differences in pulmonary protection were seen 8 and 10 months post-vaccination. In contrast, at all study periods, i.n. BCG vaccination induced significantly elevated protective splenic responses relative to s.c. immunization. At 5 of 9 time points, we observed a splenic protective response exceeding 1.9 log10 protection relative to the s.c. route. Furthermore, higher frequencies of CD4 T cells expressing IFN-γ and IFN-γ/TNF-α as well as CD8 T cells expressing IFN-γ were detected in the spleens of i.n. vaccinated mice. Using PCR arrays, significantly elevated levels of expression of IFN-γ, IL-9, IL-11 and IL-21 were also seen in the spleens at 8 months after the respiratory BCG immunization. Overall, while i.n. BCG vaccination provided short-term enhancement of protection in the lung relative to s.c immunization, potent and extremely persistent splenic protective responses were seen for at least 10 months following respiratory immunization.
Preview · Article · Aug 2014 · Clinical and vaccine Immunology: CVI
[Show abstract][Hide abstract] ABSTRACT: Clinical studies have suggested that the enumeration of mycobacteria by using automated liquid systems is a faster and simpler
alternative to quantitative cultures. Here, we show that the time to detection of M. tuberculosis growth as measured with the MGIT 320 liquid culture system inversely correlates with CFU determinations from culture on solid
media and that mycobacterial quantification using the MGIT system is faster and easier to perform than CFU plating.
Preview · Article · Dec 2013 · Clinical and vaccine Immunology: CVI
[Show abstract][Hide abstract] ABSTRACT: With tuberculosis continuing to be a major cause of global morbidity and mortality, a new vaccine is urgently needed. Tuberculosis subunit vaccines have been shown to induce robust immune responses in humans and are a potentially safer alternative to BCG for use in HIV-endemic areas. In this study, we investigated the protective efficacy of 16 different novel Mycobacterium tuberculosis antigens using an aerogenic mouse model of pulmonary tuberculosis. These antigens were tested as subunit vaccines formulated in dimethyl dioctadecyl ammonium bromide (DDA) - D(+) with trehalose 6,6 dibenenate (TDB) (DDA/TDB) adjuvant administered alone as monovalent vaccines or in combination. Six of these antigens (Rv1626, Rv1735, Rv1789, Rv2032, Rv2220, and Rv3478) were shown to consistently and significantly reduce bacterial burdens in the lungs of mice relative to nonvaccinated controls. Three of these six (Rv1789, Rv2220, and Rv3478) induced levels of protective immunity that were essentially equivalent to protection induced by the highly immunogenic antigen 85B (>0.5log10CFU reduction in the lungs relative to naïve mice). Importantly, when these three antigens were combined, protection essentially equivalent to that mediated by BCG was observed. When either Rv1626 or Rv2032 were combined with the highly protective E6-85 fusion protein (antigen 85B fused to ESAT-6), the protection observed was equivalent to BCG-induced protection at one and three months post-aerosol infection and was significantly greater than the protection observed when E6-85 was administered alone at 3 months post-infection. Using multiparameter flow cytometry, monofunctional IFNγ CD4T cells and different multifunctional CD4T cell subsets capable of secreting multiple cytokines (IFNγ, TNFα and/or IL-2) were shown to be induced by the three most protective antigens with splenocyte CD4T cell frequencies significantly greater than observed in naïve controls. The identification of these highly immunogenic TB antigens and antigen combinations should allow for improved immunization strategies against tuberculosis.
[Show abstract][Hide abstract] ABSTRACT: Although the effectiveness of BCG vaccination in preventing adult pulmonary tuberculosis (TB) has been highly variable, epidemiologic studies have suggested that BCG provides other general health benefits to vaccinees including reducing the impact of asthma, leprosy, and possibly malaria. To further evaluate whether BCG immunization protects against malarial parasitemia and to define molecular correlates of this non-specific immunity, mice were vaccinated with BCG and then challenged 2 months later with asexual blood stage Plasmodium yoelii 17XNL (PyNL) parasites. Following challenge with PyNL, significant decreases in parasitemia were observed in BCG vaccinated mice relative to naïve controls. To identify immune molecules that may be associated with the BCG-induced protection, gene expression was evaluated by RT-PCR in i) naïve controls, ii) BCG-vaccinated mice, iii) PyNL infected mice and iv) BCG vaccinated/PyNL infected mice at 0, 1, 5, and 9 days after the P. yoelii infection. The expression results showed that i) BCG immunization induces the expression of at least 18 genes including the anti-microbial molecules lactoferrin, eosinophil peroxidase, eosinophil major basic protein and the cathelicidin-related antimicrobial peptide (CRAMP); ii) an active PyNL infection suppresses the expression of important immune response molecules; and iii) the extent of PyNL-induced suppression of specific genes is reduced in BCG-vaccinated/PyNL infected mice. To validate the gene expression data, we demonstrated that pre-treatment of malaria parasites with lactoferrin or the cathelicidin LL-37 peptide decreases the level of PyNL parasitemias in mice. Overall, our study suggests that BCG vaccination induces the expression of non-specific immune molecules including antimicrobial peptides which may provide an overall benefit to vaccinees by limiting infections of unrelated pathogens such as Plasmodium parasites.
[Show abstract][Hide abstract] ABSTRACT: A new vaccination strategy is urgently needed for improved control of the global tuberculosis (TB) epidemic. Using a mouse aerosol Mycobacterium tuberculosis challenge model, we investigated the protective efficacy of a mmaA4 gene deletion mutant of Mycobacterium bovis BCG (ΔmmaA4BCG) formulated in dimethyl dioctadecyl ammonium bromide (DDA) - D(+) trehalose 6,6 dibenenate (TDB) (DDA/TDB) adjuvant. In previous studies, deletion of the mmaA4 gene was shown to reduce the suppression of IL-12 production often seen after mycobacterial infections. While the non-adjuvanted ΔmmaA4BCG strain did not protect mice substantially better than conventional BCG against a tuberculous challenge in four protection experiments, the protective responses induced by the ΔmmaA4BCG vaccine formulated in DDA/TDB adjuvant was consistently increased relative to nonadjuvanted BCG controls. Furthermore, the ΔmmaA4BCG-DDA/TDB vaccine induced significantly higher frequencies of multifunctional (MFT) CD4 T cells expressing both IFNγ and TNFα (double positive) or IFNγ, TNFα and IL-2 (triple positive) than CD4 T cells derived from mice vaccinated with BCG. These MFT cells were characterized by having higher IFNγ and TNFα median fluorescence intensity (MFI) values than monofunctional CD4 T cells. Interestingly, both BCG/adjuvant and ΔmmaA4BCG/adjuvant formulations induced significantly higher frequencies of CD4 T cells expressing TNFα and IL-2 than nonadjuvanted BCG or ΔmmaA4BCG vaccines indicating that BCG/adjuvant mixtures may be more effective at inducing central memory T cells. Importantly, when either conventional BCG or the mutant were formulated in adjuvant and administered to SCID mice or immunocompromised mice depleted of IFNγ, significantly lower vaccine-derived mycobacterial CFU were detected relative to immunodeficient mice injected with non-adjuvanted BCG. Overall, these data suggest that immunization with the ΔmmaA4BCG/adjuvant formulation may be an effective, safe, and relatively inexpensive alternative to vaccination with conventional BCG.
[Show abstract][Hide abstract] ABSTRACT: Given the considerable geographic overlap in the endemic regions for malaria and tuberculosis, it is probable that co-infections with Mycobacterium tuberculosis and Plasmodium species are prevalent. Thus, it is quite likely that both malaria and TB vaccines may be used in the same populations in endemic areas. While novel vaccines are currently being developed and tested individually against each of these pathogens, the efficacy of these vaccines has not been evaluated in co-infection models. To further assess the effectiveness of these new immunization strategies, we investigated whether co-infection with malaria would impact the anti-tuberculosis protection induced by four different types of TB vaccines in a mouse model of pulmonary tuberculosis.
[Show abstract][Hide abstract] ABSTRACT: The development of improved vaccines against Mycobacterium tuberculosis has been hindered by a limited understanding of the immune correlates of anti-tuberculosis protective immunity. In this study, we examined the relationship between long-term anti-tuberculosis protection and the mycobacterial-specific CD4 multifunctional T (MFT) cell responses induced by five different TB vaccines (live-attenuated, subunit, viral vectored, plasmid DNA, and combination vaccines) in a mouse model of pulmonary tuberculosis. In a 14-month experiment, we showed that TB vaccine-induced CD4 T cell responses were heterogenous. Antigen-specific monofunctional CD4 T cells expressing single cytokines and MFT CD4 T cells expressing multiple cytokines (IFN-γ and TNF-α, IFN-γ and IFN-γ, TNF-α, and IL-2, and all three cytokines) were identified after the immunizations. Interestingly, compared to the monofunctional cells, significantly higher median fluorescent intensities (MFIs) for IFN-γ and TNF-α were detected for triple-positive MFT CD4 T cells induced by the most protective vaccines while modest differences in relative MFI values were seen for the less protective preparations. Most importantly during the 14-month study, the levels of vaccine-induced pulmonary and splenic protective immunity correlated with the frequency and the integrated MFI (iMFI, frequency×MFI) values of triple-positive CD4 T cells that were induced by the same vaccines. These data support efforts to use MFT cell analyses as a measure of TB vaccine immunogenicity in human immunization studies.
[Show abstract][Hide abstract] ABSTRACT: Novel immunization strategies are needed to enhance the global control of tuberculosis (TB). In this study, we assessed the immunizing activity of a recombinant modified vaccinia Ankara (MVA) construct (MVA/IL-15/5Mtb) which overexpresses five Mycobacterium tuberculosis antigens (antigen 85A, antigen 85B, ESAT6, HSP60, and Mtb39), as well as the molecular adjuvant interleukin-15 (IL-15). Homologous prime/boost studies showed that the MVA/IL-15/5Mtb vaccine induced moderate but highly persistent protective immune responses for at least 16 months after the initial vaccination and that the interval between the prime and boost did not significantly alter vaccine-induced antituberculosis protective immunity. At 16 months, when the Mycobacterium bovis BCG and MVA/IL-15/5Mtb vaccine-induced protection was essentially equivalent, the protective responses after a tuberculous challenge were associated with elevated levels of gamma interferon (IFN-gamma), IL-17F, Cxcl9, and Cxcl10. To amplify the immunizing potential of the MVA/IL-15/5Mtb vaccine, a heterologous prime/boost regimen was tested using an ESAT6-antigen 85B (E6-85) fusion protein formulated in dimethyldiotacylammonium bromide/monophosphoryl lipid A (DDA/MPL) adjuvant as the priming vaccine and the MVA/IL-15/5Mtb recombinant virus as the boosting agent. When MVA/IL-15/5Mtb vaccine boosting was done at 2 or 6 months following the final fusion protein injections, the prime/boost regimen evoked protective responses against an aerogenic M. tuberculosis challenge which was equivalent to that induced by BCG immunization. Long-term memory after immunization with the E6-85-MVA/IL-15/5Mtb combination regimen was associated with the induction of monofunctional CD4 and CD8 IFN-gamma-producing T cells and multifunctional CD4 and CD8 T cells expressing IFN-gamma/tumor necrosis factor alpha (TNF-alpha), TNF-alpha/IL-2, and IFN-gamma/TNF-alpha/IL-2. In contrast, BCG-induced protection was characterized by fewer CD4 and CD8 monofunctional T cells expressing IFN-gamma and only IFN-gamma/TNF-alpha and IFN-gamma/TNF-alpha/IL-2 expressing multifunctional T (MFT) cells. Taken together, these results suggest that a heterologous prime/boost protocol using an MVA-based tuberculosis vaccines to boost after priming with TB protein/adjuvant preparations should be considered when designing long-lived TB immunization strategies.
Full-text · Article · Mar 2010 · Clinical and vaccine Immunology: CVI
[Show abstract][Hide abstract] ABSTRACT: New vaccines and novel immunization strategies are needed to improve the control of the global tuberculosis epidemic. To facilitate vaccine development, we have been creating in vitro mycobacterial intra-macrophage growth inhibition assays. Here we describe the development of an in vitro assay designed for BSL-2 laboratories which measures the capacity of vaccine-induced immune splenocytes to control the growth of isoniazid-resistant Mycobacterium bovis BCG (INH(r) BCG). The use of the INH(r) BCG as the infecting organism allows the discrimination of BCG bacilli used in murine vaccinations from BCG used in the in vitro assay. In this study, we showed that protective immune responses evoked by four different types of Mycobacterium tuberculosis vaccines [BCG, an ESAT6/Antigen 85B fusion protein formulated in DDA/MPL adjuvant, a DNA vaccine expressing the same fusion protein, and a TB Modified Vaccinia Ankara construct expressing four TB antigens (MVA-4TB)] were detected. Importantly, the levels of vaccine-induced protective immunity seen in the in vitro assay correlated with the results from in vivo protection studies in the mouse model of pulmonary tuberculosis. Furthermore, the growth inhibition data for the INH(r) BCG assay was similar to the previously reported results for a M. tuberculosis infection assay. The cytokine expression profiles at day 7 of the INH(r) BCG growth inhibition studies were also similar but not identical to the cytokine patterns detected in earlier M. tuberculosis co-culture assays. Overall, we have shown that a BSL-2 compatible in vitro growth inhibition assay using INH(r) BCG as the intra-macrophage target organism should be useful in developing and evaluating new TB immunization strategies.
[Show abstract][Hide abstract] ABSTRACT: The development and characterization of new tuberculosis (TB) vaccines has been impeded by the lack of reproducible and reliable in vitro assays for measuring vaccine activity. In this study, we developed a murine in vitro mycobacterial growth inhibition assay for evaluating TB vaccines that directly assesses the capacity of immune splenocytes to control the growth of Mycobacterium tuberculosis within infected macrophages. Using this in vitro assay, protective immune responses induced by immunization with five different types of TB vaccine preparations (Mycobacterium bovis BCG, an attenuated M. tuberculosis mutant strain, a DNA vaccine, a modified vaccinia virus strain Ankara [MVA] construct expressing four TB antigens, and a TB fusion protein formulated in adjuvant) can be detected. Importantly, the levels of vaccine-induced mycobacterial growth-inhibitory responses seen in vitro after 1 week of coculture correlated with the protective immune responses detected in vivo at 28 days postchallenge in a mouse model of pulmonary tuberculosis. In addition, similar patterns of cytokine expression were evoked at day 7 of the in vitro culture by immune splenocytes taken from animals immunized with the different TB vaccines. Among the consistently upregulated cytokines detected in the immune cocultures are gamma interferon, growth differentiation factor 15, interleukin-21 (IL-21), IL-27, and tumor necrosis factor alpha. Overall, we have developed an in vitro functional assay that may be useful for screening and comparing new TB vaccine preparations, investigating vaccine-induced protective mechanisms, and assessing manufacturing issues, including product potency and stability.
Full-text · Article · Jun 2009 · Clinical and vaccine Immunology: CVI
[Show abstract][Hide abstract] ABSTRACT: In this study, the early pulmonary cytokine and chemokine responses in mice immunized with either BCG vaccine, a DeltasecA2 mutant of Mycobacterium tuberculosis, or a DNA vaccine expressing an ESAT6-antigen 85B fusion protein and then aerogenically challenged with a low dose of M. tuberculosis were evaluated by PCR array. The cellular immune responses at day 10 postchallenge were essentially equivalent in the lungs of mice immunized with either the highly immunogenic BCG vaccine or the DeltasecA2 M. tuberculosis mutant strain. Specifically, 12 immune biomolecules (including gamma interferon [IFN-gamma], interleukin-21 [IL-21], IL-27, IL-17f, CXCL9, CXCL10, and CXCL11) were differentially regulated, relative to the levels for naïve controls, in the lungs of vaccinated mice at this time point. Although the vaccine-related immune responses evoked in mice immunized with the DNA vaccine were relatively limited at 10 days postinfection, upregulation of IFN-gamma RNA synthesis as well as increased expression levels of CXCL9, CXCL10, and CXCL11 chemokines were detected.
Full-text · Article · Dec 2008 · Clinical and vaccine Immunology: CVI
[Show abstract][Hide abstract] ABSTRACT: New post-exposure tuberculosis vaccination strategies are being developed to prevent disease in individuals latently infected with Mycobacterium tuberculosis. However, concerns about the potential induction of deleterious Koch-like reactions after immunization of persons with latent tuberculosis has limited progress in assessing the effectiveness of post-exposure vaccination. To evaluate the safety of immunization after M. tuberculosis infection, two mouse models were established, a drug treatment low bacterial burden model and an active disease model. Twelve different M. tuberculosis antigen preparations and vaccines (including DNA, subunit, viral vectored, and live, attenuated vaccines) were evaluated using these mouse models. In the low bacterial burden model, post-exposure vaccination did not induce significant reactivational disease and only injection of BCG evoked increases in lung inflammatory responses at 1 month after the immunizations. Additionally, although significant increases in lung inflammation were seen for animals injected with the hps65 DNA vaccine or a M. tuberculosis culture supernatant preparation, no differences in the survival periods were detected between vaccinated and non-vaccinated mice at 10 months post-immunization using the low bacterial burden model. For the active disease model, significantly more lung inflammation was observed at 1 month after administration of the hsp65 DNA vaccine but none of the antigen preparations tested increased the lung bacterial burdens at this early time point. Furthermore, vaccination of diseased mice with BCG or TB DNA vaccines did not significantly affect mortality rates compared to non-vaccinated controls at 10 months post-immunization. Overall, these data suggest that while the potential risk of inducing Koch-like reactions is low after immunization of persons with latent tuberculosis, extreme caution is still needed as post-exposure vaccines progress from pre-clinical experiments into the initial phases of clinical testing.
[Show abstract][Hide abstract] ABSTRACT: Recent preclinical and epidemiologic studies have suggested that certain Mycobacterium tuberculosis genotypes (in particular, Beijing lineage strains) may be resistant to Mycobacterium bovis BCG vaccine-induced antituberculosis protective immunity. To investigate the strain specificity of BCG-induced protective responses in a murine model of pulmonary tuberculosis, C57BL/6 mice were vaccinated with BCG vaccine and then challenged 2 months later with one of nine M. tuberculosis isolates. Four of these strains were from the W-Beijing lineage (HN878, N4, NHN5, and ChS) while four were non-Beijing-type isolates (C913, CDC1551, NY669, and NY920). As a control, the WHO standard M. tuberculosis Erdman strain was evaluated in these vaccination/challenge experiments. To assess the protective responses evoked by BCG immunization, organ bacterial burdens and lung pathology were assessed in vaccinated and naïve mice at 4, 12, and 20 weeks postchallenge as well as during the day of infection. At 4 weeks after the aerosol challenge with each of these strains, significantly reduced bacterial growth in the lungs and spleens and significantly improved lung pathology were seen in all vaccinated animals compared to naïve controls. After 12 weeks, reduced organ bacterial burdens were detected in vaccinated animals infected with six of nine challenge strains. Although lung CFU values were lower in vaccinated mice for only three of nine groups at 20 weeks postchallenge, significantly decreased lung inflammation was seen in all immunized animals relative to controls at 20 weeks postchallenge. Taken together, these data demonstrate that BCG vaccination protects against infection with diverse M. tuberculosis strains in the mouse model of pulmonary tuberculosis and suggest that strain-specific resistance to BCG-induced protective immunity may be uncommon.
Full-text · Article · Sep 2008 · Infection and immunity
[Show abstract][Hide abstract] ABSTRACT: Although vaccination against tuberculosis (TB) was initiated more than 80 years ago, the correlates of protective immunity against infection by Mycobacterium tuberculosis have still not been well defined. To investigate the vaccine-induced immune responses against TB, we evaluated the early pulmonary cytokine responses elicited by a low dose M. tuberculosis aerogenic challenge in mice that had been immunized with either BCG or a TB DNA vaccine cocktail, two vaccine preparations that induce long-term protection in the mouse model of pulmonary TB. Using three different assays, we showed that specific cytokine responses were elevated in the lungs of vaccinated mice (relative to naïve controls) during the second week post-challenge. By measuring cytokine levels in the bronchoalveolar lavage fluid (BAL) and cytokine mRNA concentrations in pulmonary cells, the levels of IFN-gamma, IL-12, and RANTES were shown to be elevated from days 7-14 post-challenge in the lungs. By intracellular cytokine staining (ICS), increased numbers of lung CD4 and CD8 cells expressing IFN-gamma were also seen at days 10 and 14 after the infection. Moreover, increased post-challenge IFN-gamma levels were detected using the ICS and cytokine mRNA assays in aging BCG-immunized mice that had been effectively boosted with a TB DNA vaccine. Taken together, these data suggest that the post-infection induction of early type 1 cytokine responses correlate with the induction of long-term protective immunity in vaccinated mice.
[Show abstract][Hide abstract] ABSTRACT: To improve DNA vaccination against Mycobacterium tuberculosis, we evaluated the effectiveness of a Sindbis virus-based DNA construct expressing the tuberculosis antigen 85B (Sin85B). The protective efficacy of Sin85B was initially assessed by aerogenically challenging immunized C57BL/6 mice with virulent Mycobacterium tuberculosis. At 1 and 7 months postinfection, the lung bacterial burdens were considerably reduced and the lung pathology was improved in vaccinated mice compared to naive controls. Furthermore, the mean survival period for Sin85B-immunized mice (305 +/- 9 days) after the tuberculous challenge was extended 102 days relative to the naive mice (203 +/- 13 days) and was essentially equivalent to the survival time of Mycobacterium bovis BCG-vaccinated mice (294 +/- 15 days). The essential role of gamma interferon (IFN-gamma) in Sin85B-mediated protection was established by showing that significantly increased levels of IFN-gamma mRNA were present postinfection in lung cells from vaccinated mice relative to control mice and by demonstrating that IFN-gamma depletion prior to challenge abolished the vaccine-induced protection. The substantial antituberculosis protective responses induced by Sin85B immunization of CD4-/- mice strongly suggested that CD8 cells partially mediate Sin85B-induced protective immunity. Interestingly, Sin85B vaccination did not protect RNase L-/- (a key enzyme in the innate antiviral response) mice while significant protection was detected in RNase L-/- mice immunized with either BCG or a conventional DNA plasmid expressing antigen 85B. These data show that immunization with Sin85B offers protection similar to BCG in a murine model of pulmonary tuberculosis and suggest that Sin85B-induced protection is dependent upon both innate and acquired immune mechanisms.
Full-text · Article · Dec 2005 · Infection and Immunity
[Show abstract][Hide abstract] ABSTRACT: In this study, we evaluated the protective efficacy of a DNA vaccine (pE6/85) expressing an ESAT6-Ag85B fusion protein against a primary Mycobacterium tuberculosis infection in mice. In short-term studies, vaccination with pE6/85 protected as well as Mycobacterium bovis BCG immunization with similar lung pathology and bacterial burdens detected 28 days after a low dose aerogenic challenge (>1.0 log(10) reduction relative to naïves). In a survival experiment, the protection induced by pE6/85 immunization was also not significantly different than that elicited by BCG vaccination with the mean-times-to-death (+/-standard error of the mean) being 102+/-20, 271+/-32 and 299+/-14 days for naïve, pE6/85 and BCG-vaccinated mice, respectively. Furthermore, boosting with pE6/85 but not BCG or a DNA vaccine cocktail at 1 year after an initial BCG immunization (when BCG-induced protection was declining), augmented protection in the lung at 15 and 18 months to levels detected at 3 months post-BCG vaccination.
[Show abstract][Hide abstract] ABSTRACT: Tuberculosis (TB) is the most common opportunistic disease and a potentially fatal complication among immunocompromised individuals
infected with human immunodeficiency virus (HIV). Effective vaccination against TB in persons with HIV has been considered
unlikely because of the central role that CD4 cells play in controlling tuberculous infections. Here we show that the vaccination
of CD8−/− mice with a TB DNA vaccine cocktail did not significantly enhance protective responses to a Mycobacterium tuberculosis infection. In contrast, immunization with a DNA vaccine cocktail or with the current TB vaccine, Mycobacterium bovis BCG, induced considerable antituberculosis protective immunity in immune-deficient mice lacking CD4 cells. In vaccinated
CD4−/− animals, substantially reduced bacterial burdens in organs and much improved lung pathology were seen 1 month after an aerogenic
M. tuberculosis challenge. Importantly, the postchallenge mean times to death of vaccinated CD4−/− mice were significantly extended (mean with DNA cocktail, 172 ± 7 days; mean with BCG, 156 ± 22 days) compared to that of
naïve CD4−/− mice (33 ± 6 days). Furthermore, the treatment of DNA-vaccinated CD4−/− mice with an anti-CD8 or anti-gamma interferon (IFN-γ) antibody significantly reduced the effect of immunization, and neither
IFN-γ−/− nor tumor necrosis factor receptor-deficient mice were protected by DNA immunization; therefore, the primary vaccine-induced
protective mechanism in these immune-deficient mice likely involves the secretion of cytokines from activated CD8 cells. The
substantial CD8-mediated protective immunity that was generated in the absence of CD4 cells suggests that it may be possible
to develop effective TB vaccines for use in HIV-infected populations.
Full-text · Article · Apr 2004 · Infection and Immunity