The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
Maria Cristina Roquebarreira - One of the best experts on this subject based on the ideXlab platform.
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oral administration of a live attenuated salmonella vaccine strain expressing the vapa protein induces protection against infection by rhodococcus equi
Microbes and Infection, 2007Co-Authors: Aline F. Oliveira, Luciana Colbachini Ferraz, Marcelo Brocchi, Maria Cristina RoquebarreiraAbstract:Abstract Rhodococcus equi remains one of the most important pathogens of foals and vaccination strategies to prevent Rhodococcosis are under increasing investigation. Attenuated Salmonella strains carrying heterologous antigens offer an advantageous alternative to conventional vaccines, especially because they induce mucosal and systemic immunity. In this work, we expressed the VapA antigen from R. equi in a Salmonella enterica Typhimurium strain, which was able to colonize and persist in the lymphoid tissue of BALB/c mice. Two days after being challenged, oral immunized mice presented a 3- to 7-fold increase in R. equi clearance. This was progressively enhanced during infection and, on the 10th day, a CFU value 50-fold lower than that recovered from non-immunized mice was attained. The number of hepatic granulomas was 2 times lower, and leukocyte infiltration was transiently detected in immunized mice, contrasting with the severe inflammation and necrosis presented by non-immunized mice. Infection with 1 × 107 R. equi CFU caused 100% mortality in the control groups, while all immunized mice survived. This protection was associated with the detection of high levels of anti-VapA IgG in the serum of the vaccinated mice, predominantly the IgG2a isotype. Our results suggest that attenuated Salmonella encoding VapA may be used in foals to prevent Rhodococcosis.
Aline F. Oliveira - One of the best experts on this subject based on the ideXlab platform.
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Vaccination of Mice with Virulence-Associated Protein G (VapG) Antigen Confers Partial Protection against Rhodococcus equi Infection through Induced Humoral Immunity
Frontiers Media S.A., 2017Co-Authors: Marcel M. Trevisani, Ebert S. Hanna, Aline F. Oliveira, Silvia A. Cardoso, Maria C. Roque-barreira, Sandro G. SoaresAbstract:Rhodococcus equi is a facultative intracellular bacterium causing severe pyogranulomatous pneumonia, ulcerative enterocolitis, and mesenteric lymphadenopathy in foals aged less than 6 months. Less frequently, this pathogen affects various other species, such as pigs, cattle, cats, and even humans. Although Rhodococcosis is treated with a combination of antimicrobial agents, resistance is developed in some cases, and thus, antimicrobial susceptibility must be monitored and managed. Considering these limitations of the current therapy and unavailability of a vaccine to prevent the disease, research is particularly focused on the development of an effective vaccine against Rhodococcosis. Most vaccines undergoing development utilize the virulence-associated protein (Vap) A antigen, which was identified previously as a key virulence factor of R. equi. Nevertheless, other proteins, such as VapG, present in most virulent R. equi strains, are also encoded by vap genes located on the R. equi bacterial virulence plasmid. In the present study, we evaluated the effect of VapG immunization on the survival of R. equi-challenged mice. We used attenuated Salmonella as a carrier for VapG (Salmonella-vapG+), a procedure previously adopted to develop a VapA-based vaccine. We observed that vaccination with Salmonella-vapG+ induced both an increased IFN-γ, IL-12, and TNF-α production, and a decreased bacterial burden in organs of the R. equi-challenged mice. Nevertheless, Salmonella-vapG+ vaccination protected only 50% of the mice challenged with a lethal dose of R. equi. Interestingly, we observed an increased frequency of B cells in the spleen of Salmonella-vapG+-vaccinated mice and showed that Salmonella-vapG+-vaccinated R. equi-challenged B-cell-knockout mice did not reduce the bacterial burden. Given these results, we discussed the potential role of the humoral immune response induced by Salmonella-vapG+ vaccination in conferring protection against R. equi infection, as well as the employment of VapG antigen for obtaining hyperimmune plasma to prevent rhodoccocosis in young foals
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oral administration of a live attenuated salmonella vaccine strain expressing the vapa protein induces protection against infection by rhodococcus equi
Microbes and Infection, 2007Co-Authors: Aline F. Oliveira, Luciana Colbachini Ferraz, Marcelo Brocchi, Maria Cristina RoquebarreiraAbstract:Abstract Rhodococcus equi remains one of the most important pathogens of foals and vaccination strategies to prevent Rhodococcosis are under increasing investigation. Attenuated Salmonella strains carrying heterologous antigens offer an advantageous alternative to conventional vaccines, especially because they induce mucosal and systemic immunity. In this work, we expressed the VapA antigen from R. equi in a Salmonella enterica Typhimurium strain, which was able to colonize and persist in the lymphoid tissue of BALB/c mice. Two days after being challenged, oral immunized mice presented a 3- to 7-fold increase in R. equi clearance. This was progressively enhanced during infection and, on the 10th day, a CFU value 50-fold lower than that recovered from non-immunized mice was attained. The number of hepatic granulomas was 2 times lower, and leukocyte infiltration was transiently detected in immunized mice, contrasting with the severe inflammation and necrosis presented by non-immunized mice. Infection with 1 × 107 R. equi CFU caused 100% mortality in the control groups, while all immunized mice survived. This protection was associated with the detection of high levels of anti-VapA IgG in the serum of the vaccinated mice, predominantly the IgG2a isotype. Our results suggest that attenuated Salmonella encoding VapA may be used in foals to prevent Rhodococcosis.
Marcelo Brocchi - One of the best experts on this subject based on the ideXlab platform.
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oral administration of a live attenuated salmonella vaccine strain expressing the vapa protein induces protection against infection by rhodococcus equi
Microbes and Infection, 2007Co-Authors: Aline F. Oliveira, Luciana Colbachini Ferraz, Marcelo Brocchi, Maria Cristina RoquebarreiraAbstract:Abstract Rhodococcus equi remains one of the most important pathogens of foals and vaccination strategies to prevent Rhodococcosis are under increasing investigation. Attenuated Salmonella strains carrying heterologous antigens offer an advantageous alternative to conventional vaccines, especially because they induce mucosal and systemic immunity. In this work, we expressed the VapA antigen from R. equi in a Salmonella enterica Typhimurium strain, which was able to colonize and persist in the lymphoid tissue of BALB/c mice. Two days after being challenged, oral immunized mice presented a 3- to 7-fold increase in R. equi clearance. This was progressively enhanced during infection and, on the 10th day, a CFU value 50-fold lower than that recovered from non-immunized mice was attained. The number of hepatic granulomas was 2 times lower, and leukocyte infiltration was transiently detected in immunized mice, contrasting with the severe inflammation and necrosis presented by non-immunized mice. Infection with 1 × 107 R. equi CFU caused 100% mortality in the control groups, while all immunized mice survived. This protection was associated with the detection of high levels of anti-VapA IgG in the serum of the vaccinated mice, predominantly the IgG2a isotype. Our results suggest that attenuated Salmonella encoding VapA may be used in foals to prevent Rhodococcosis.
Luciana Colbachini Ferraz - One of the best experts on this subject based on the ideXlab platform.
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oral administration of a live attenuated salmonella vaccine strain expressing the vapa protein induces protection against infection by rhodococcus equi
Microbes and Infection, 2007Co-Authors: Aline F. Oliveira, Luciana Colbachini Ferraz, Marcelo Brocchi, Maria Cristina RoquebarreiraAbstract:Abstract Rhodococcus equi remains one of the most important pathogens of foals and vaccination strategies to prevent Rhodococcosis are under increasing investigation. Attenuated Salmonella strains carrying heterologous antigens offer an advantageous alternative to conventional vaccines, especially because they induce mucosal and systemic immunity. In this work, we expressed the VapA antigen from R. equi in a Salmonella enterica Typhimurium strain, which was able to colonize and persist in the lymphoid tissue of BALB/c mice. Two days after being challenged, oral immunized mice presented a 3- to 7-fold increase in R. equi clearance. This was progressively enhanced during infection and, on the 10th day, a CFU value 50-fold lower than that recovered from non-immunized mice was attained. The number of hepatic granulomas was 2 times lower, and leukocyte infiltration was transiently detected in immunized mice, contrasting with the severe inflammation and necrosis presented by non-immunized mice. Infection with 1 × 107 R. equi CFU caused 100% mortality in the control groups, while all immunized mice survived. This protection was associated with the detection of high levels of anti-VapA IgG in the serum of the vaccinated mice, predominantly the IgG2a isotype. Our results suggest that attenuated Salmonella encoding VapA may be used in foals to prevent Rhodococcosis.
Julien Cauchard - One of the best experts on this subject based on the ideXlab platform.
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In vitro potential of equine DEFA1 and eCATH1 as alternative antimicrobial drugs in Rhodococcosis treatment
Antimicrobial agents and chemotherapy, 2012Co-Authors: Margot Schlusselhuber, Sascha Jung, Oliver Bruhn, Didier Goux, Matthias Leippe, Roland Leclercq, Claire Laugier, Joachim Grötzinger, Julien CauchardAbstract:ABSTRACT Rhodococcus equi, the causal agent of Rhodococcosis, is a severe pathogen of foals but also of immunodeficient humans, causing bronchopneumonia. The pathogen is often found together with Klebsiella pneumoniae or Streptococcus zooepidemicus in foals. Of great concern is the fact that some R. equi strains are already resistant to commonly used antibiotics. In the present study, we evaluated the in vitro potential of two equine antimicrobial peptides (AMPs), eCATH1 and DEFA1, as new drugs against R. equi and its associated pathogens. The peptides led to growth inhibition and death of R. equi and S. zooepidemicus at low micromolar concentrations. Moreover, eCATH1 was able to inhibit growth of K. pneumoniae. Both peptides caused rapid disruption of the R. equi membrane, leading to cell lysis. Interestingly, eCATH1 had a synergic effect together with rifampin. Furthermore, eCATH1 was not cytotoxic against mammalian cells at bacteriolytic concentrations and maintained its high killing activity even at physiological salt concentrations. Our data suggest that equine AMPs, especially eCATH1, may be promising candidates for alternative drugs to control R. equi in mono- and coinfections.
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Mucosal co-immunization of mice with recombinant lactococci secreting VapA antigen and leptin elicits a protective immune response against Rhodococcus equi infection
Vaccine, 2011Co-Authors: Séverine Cauchard, Claire Laugier, Luis G. Bermúdez-humarán, S. Blugeon, Philippe Langella, Julien CauchardAbstract:Rhodococcus equi causes severe pneumonia in foals and has recently gained attention as a significant opportunistic pathogen in immunocompromised humans. However, no effective vaccine to prevent Rhodococcosis is currently available. In this study, we have engineered the food-grade bacterium Lactococcus lactis to secrete the virulence-associated protein A from R. equi (LL-VapA). The immunogenic potential of LL-VapA strain was then evaluated after either intragastric or intranasal immunization in mice either alone or in combination with LL-Lep, a recombinant strain of L. lactis secreting biologically active leptin, a pleiotropic hormone with significant immunomodulatory properties. Intragastric administration of LL-VapA led to the highest VapA-specific mucosal response whereas intranasal administration led to the highest systemic immune responses. Cytokines released from in vitro-stimulated spleen cells show both a strong IFN-γ response and an increase of IL-4 level in all immunized groups, except for the group intranasally co-administered with both LL-VapA and LL-Lep. Strikingly, a significant reduction in R. equi viable counts in liver and spleen was observed four days after intravenous challenge with a virulent strain of R. equi in all immunized groups except for the group vaccinated by intragastric route with LL-VapA. Altogether, our results demonstrate that LL-VapA can evoke a TH1-based protective immune response in intranasally immunized mice. This response is enhanced when co-administered with LL-Lep strain, whereas only co-administration of LL-VapA and LL-Lep can induce a protective immune response in intragastric vaccinated mice, associated with a TH1/TH2 cytokine response.