RESUMEN
Translation engineering and bioinformatics have accelerated the rate at which gene sequences can be improved to generate multi-epitope proteins. Strong antigenic proteins for tuberculosis diagnosis include individual ESAT6 and CFP10 proteins or derived peptides. Obtention of heterologous multi-component antigens in E. coli without forming inclusion bodies remain a biotechnological challenge. The gene sequence for ESAT6-CFP10 fusion antigen was optimized by codon bias adjust for high-level expression as a soluble protein. The obtained fusion protein of 23.7 kDa was observed by SDS-PAGE and Western blot analysis after Ni-affinity chromatography and the yield of expressed soluble protein reached a concentration of approximately 67 mg/L in shake flask culture after IPTG induction. Antigenicity was evaluated at 4 µg/mL in whole blood cultures from bovines, and protein stimuli were assessed using a specific in vitro IFN-γ release assay. The hybrid protein was able to stimulate T-cell specific responses of bovine TB suspects. The results indicate that improved E. coli codon usage is a good and cost-effective strategy to potentialize large scale production of multi-epitope proteins with sustained antigenic properties for diagnostic purposes.
Asunto(s)
Antígenos Bacterianos/genética , Proteínas Bacterianas/genética , Mycobacterium bovis/inmunología , Fragmentos de Péptidos/genética , Proteínas Recombinantes de Fusión/administración & dosificación , Vacunas contra la Tuberculosis/administración & dosificación , Tuberculosis Bovina/prevención & control , Secuencia de Aminoácidos , Animales , Antígenos Bacterianos/inmunología , Proteínas Bacterianas/inmunología , Bovinos , Clonación Molecular , Codón , Escherichia coli/genética , Escherichia coli/metabolismo , Expresión Génica , Vectores Genéticos/química , Vectores Genéticos/metabolismo , Histidina/genética , Histidina/metabolismo , Inmunogenicidad Vacunal , Interferón gamma/biosíntesis , Mycobacterium bovis/química , Mycobacterium bovis/genética , Mycobacterium tuberculosis/química , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/inmunología , Oligopéptidos/genética , Oligopéptidos/metabolismo , Fragmentos de Péptidos/inmunología , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/inmunología , Alineación de Secuencia , Vacunas contra la Tuberculosis/genética , Vacunas contra la Tuberculosis/inmunología , Tuberculosis Bovina/inmunología , Tuberculosis Bovina/microbiología , Vacunación/métodosRESUMEN
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.