RESUMO
Cattle vaccination is an attractive approach in compliance with control and eradication programs against Bovine Tuberculosis (bTB). Today, there is no anti bTB vaccine licensed. Two vaccine candidates, MbΔmce2 and MbΔmce2-phoP previously designed were evaluated in BALB/c mice, including the parental M. bovis NCTC10772 and a M. bovis hypervirulent Mb04-303 strains as controls. Sentinel mice (non-inoculated) cohoused with subcutaneous inoculated mice. Persistence, visible tuberculosis lesions (VTL) in lungs and spleens and bacillary load were investigated subcutaneously delivered at 60 and 90 days after inoculation (dpi) as well as their potential transmission to naïve mice. While a 100% survival was observed at 90 dpi without VTL in all groups, transmission was not evidenced in the sentinels mice. Vaccine candidates and control strains were isolated from the spleen of all inoculated mice, while Mb04-303 was isolated from the lungs of one inoculated mouse. Vaccine candidate's attenuation considering survival, lung bacillary load and VTL was confirmed, administrated by the subcutaneous route. Future experiments are necessary to demonstrate whether the persistence of both mutants in the spleen, with low CFU, remains over time to increase the potential increasing risk of dissemination to organs and subsequent transmission to other animals by airborne or other routes.
Assuntos
Mycobacterium bovis , Mycobacterium tuberculosis , Tuberculose Bovina , Tuberculose , Animais , Vacina BCG , Bovinos , Modelos Animais de Doenças , Camundongos , Camundongos Endogâmicos BALB C , Tuberculose/prevenção & controle , Tuberculose Bovina/prevenção & controleRESUMO
Background: The fusion protein H65, composed of Mycobacterium tuberculosis (TB) ESX-secreted antigens, has improved the bacillus Calmette-Guerin-induced immune protection in a mouse model of bovine TB when formulated in the liposomal adjuvant CAF01. In this study, we aimed to evaluate the protective efficacy of an attenuated Mycobacterium bovis strain - a mutant in mce2 and phoP genes - combined with H65+CAF01 immunization. We evaluated the protection of MbΔmce2-phoP alone or combined with H65+CAF01 against M. bovis challenge in mice. Methods: Groups of BALBc mice were inoculated with the vaccine candidates or phosphate buffered saline (PBS), and 6 weeks after the last immunization, the animals were aerogenically challenged with virulent M. bovis. Bacterial load in organs was counted after 45 days of the challenge. One-way analysis of variance and Bonferroni's posttest were used for statistical analysis. Results: All vaccinated mice showed reduced bacterial loads in lungs compared to unvaccinated animals. However, the protection level was similar between vaccinated groups. Conclusions: The MbΔmce2-phoP strain combined with three doses of H65+CAF01 induced equivalent protection than the MbΔmce2-phoP strain alone. Thus, the use of combined vaccination strategies requires a careful analysis of the potential interactions of each of their components with the host's immune system.
Assuntos
Mycobacterium bovis , Mycobacterium tuberculosis , Vacinas contra a Tuberculose , Tuberculose Bovina , Tuberculose , Animais , Vacina BCG , Bovinos , Modelos Animais de Doenças , Humanos , Pulmão/microbiologia , Camundongos , Mycobacterium bovis/genética , Mycobacterium tuberculosis/genética , Tuberculose/prevenção & controle , Vacinas contra a Tuberculose/genética , Tuberculose Bovina/prevenção & controle , Vacinas AtenuadasRESUMO
H65, a fusion protein of three pairs of ESX-secreted antigens of Mycobacterium tuberculosis and Mycobacterium bovis, formulated with the liposomal adjuvant CAF01 has been shown to confer protection against M. tuberculosis infection in mice. In this study, we evaluated the impact of combining BCG with H65 + CAF01 immunization in a M. bovis mouse model of infection. We found that a BCG-H65 + CAF01/ H65 + CAF01 prime-boost scheme induced higher protection than BCG and H65 + CAF01 alone. Altogether, H65 antigen formulated in liposomal adjuvant improved the BCG-induced immune protection, thus making this vaccine strategy a promising tool to control bovine tuberculosis.
Assuntos
Vacina BCG/imunologia , Mycobacterium bovis/imunologia , Tuberculose Bovina/prevenção & controle , Adjuvantes Imunológicos/farmacologia , Animais , Bovinos , Modelos Animais de Doenças , Feminino , Camundongos , Camundongos Endogâmicos BALB C , Mycobacterium tuberculosis/imunologia , Tuberculose Bovina/imunologia , Vacinas de Subunidades Antigênicas/imunologia , Vacinas Sintéticas/imunologiaRESUMO
Background: Bovine tuberculosis (bTB) is a zoonotic disease caused by Mycobacterium bovis that mainly affects cattle. Although vaccination is the most effective strategy to control bTB, it may interfere with the diagnosis of the infection. Therefore, ancillary tests to differentiate vaccinated from infected animals (DIVA) are essential in a cattle vaccination scenario. ESAT-6 and CFP-10 are the most promissory DIVA antigens. Method: In this study, we deleted esat6 and cfp10 genes from the M. bovis Δ mce2 live-attenuated vaccine candidate and evaluated its protection level against bTB in BALBc mice. Results: We found that the M. bovis strain mutant in mce2, esat-6 and cfp-10 failed to confer protection against virulent M. bovis challenge in a mouse model of tuberculosis. Conclusions: This result highlights the relevant role of ESAT-6 and CFP-10 in the induction of protective immune response against M. bovis infection and reveals the need of evaluating different strategies to compensate for the lack of these DIVA antigens in new vaccine formulations.
Assuntos
Mycobacterium bovis , Tuberculose Bovina , Vacinas , Animais , Antígenos de Bactérias , Proteínas de Bactérias , Bovinos , Camundongos , TuberculoseRESUMO
BACKGROUND: The identification and characterization of antigens expressed in Trypanosoma cruzi stages that parasitize mammals are essential steps for the development of new vaccines and diagnostics. Genes that are preferentially expressed in trypomastigotes may be involved in key processes that define the biology of trypomastigotes, like cell invasion and immune system evasion. METHODOLOGY/PRINCIPAL FINDINGS: With the initial aim of identifying trypomastigote-specific expressed tags, we constructed and sequenced an epimastigote-subtracted trypomastigote cDNA library (library TcT-E). More than 45% of the sequenced clones of the library could not be mapped to previously annotated mRNAs or proteins. We validated the presence of these transcripts by reverse northern blot and northern blot experiments, therefore providing novel information about the mRNA expression of these genes in trypomastigotes. A 280-bp consensus element (TcT-E element, TcT-Eelem) located at the 3' untranslated region (3' UTR) of many different open reading frames (ORFs) was identified after clustering the TcT-E dataset. Using an RT-PCR approach, we were able to amplify different mature mRNAs containing the same TcT-Eelem in the 3' UTR. The proteins encoded by these ORFs are members of a novel surface protein family in T. cruzi, (which we named TcTASV for T. cruzi Trypomastigote, Alanine, Serine and Valine rich proteins). All members of the TcTASV family have conserved coding amino- and carboxy-termini, and a central variable core that allows partitioning of TcTASV proteins into three subfamilies. Analysis of the T. cruzi genome database resulted in the identification of 38 genes/ORFs for the whole TcTASV family in the reference CL-Brener strain (lineage II). Because this protein family was not found in other trypanosomatids, we also looked for the presence of TcTASV genes in other evolutionary lineages of T. cruzi, sequencing 48 and 28 TcTASVs members from the RA (lineage II) and Dm28 (lineage I) T. cruzi strains respectively. Detailed phylogenetic analyses of TcTASV gene products show that this gene family is different from previously characterized mucin (TcMUCII), mucin-like, and MASP protein families. CONCLUSIONS/SIGNIFICANCE: We identified TcTASV, a new gene family of surface proteins in T. cruzi.