Protein complex from human milk enhances the activity of antibiotics and drugs against Mycobacterium tuberculosis.

Mycobacterium tuberculosis, the causative agent of human tuberculosis (TB), has surpassed HIV/AIDS as the leading cause of death from a single infectious agent. The increasing occurrence of drug-resistant strains has become a major challenge for health care systems and, in some cases, has rendered TB untreatable. However, the development of new TB drugs has been plagued with high failure rates and costs. Alternative strategies to increase the efficacy of current TB treatment regimens include host-directed therapies or agents that make M. tuberculosis more susceptible to existing TB drugs. In this study, we show that HAMLET, an α-lactalbumin-oleic acid complex derived from human milk, has bactericidal activity against M. tuberculosis HAMLET consists of a micellar oleic acid core surrounded by a shell of partially denatured α-lactalbumin molecules and unloads oleic acid into cells upon contact with lipid membranes. At sublethal concentrations, HAMLET potentiated a remarkably broad array of TB drugs and antibiotics against M. tuberculosis For example, the minimal inhibitory concentrations of rifampin, bedaquiline, delamanid, and clarithromycin were decreased by 8- to 16-fold. HAMLET also killed M. tuberculosis and enhanced the efficacy of TB drugs inside macrophages, a natural habitat of M. tuberculosis Previous studies showed that HAMLET is stable after oral delivery in mice and nontoxic in humans and that it is possible to package hydrophobic compounds in the oleic acid core of HAMLET to increase their solubility and metabolic stability. The potential of HAMLET and other liprotides as drug delivery and sensitization agents in TB chemotherapy is discussed here.Microbiology and Molecular Genetic

Use of touch-down polymerase chain reaction to enhance the sensitivity of Mycobacterium bovis detection

The confirmatory diagnosis of Mycobacterium bovis (M. bovis) in animal samples is carried out by culture in Stonebrink media. However, culture is very slow because of the extremely long duplication time of the bacillus and difficult because of the scarcity of bacilli in diagnostic samples. This study describes the development of a single-tube touch-down polymerase chain reaction (PCR) protocol for the detection of M. bovis using primers that target the IS6110 element. Spiked water and milk as well as routine diagnostic samples (milk and nasal swabs) from M. bovis–positive cattle were tested. This protocol allows the rapid and sensitive detection of M. bovis in bovine samples by enhancing the sensitivity of standard PCR amplification.Instituto de BiotecnologíaFil: Zumarraga, Martin Jose. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Biotecnología; ArgentinaFil: Meikle, Virginia. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Biotecnología; ArgentinaFil: Bernardelli, Amelia. Servicio Nacional de Sanidad y Calidad Agroalimentaria. Dirección de Laboratorios y Control Técnico; ArgentinaFil: Abdala, Alejandro Ariel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Tarabla, Hector Dante. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Romano, Maria Isabel. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Biotecnología; ArgentinaFil: Cataldi, Angel Adrian. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Biotecnología; Argentin

Assessment of the Immune Responses Induced in Cattle after Inoculation of a Mycobacterium bovis Strain Deleted in Two mce2 Genes

The generation of efficient candidate vaccines against bovine tuberculosis will contribute to the control of this zoonotic disease. Rationally attenuated Mycobacterium bovis strains generated by knockout of virulence genes are promising candidate vaccines. However, to be effective, these candidate vaccines should at least maintain the immunological properties of their virulent parental M. bovis strains. Therefore, the aim of this study was to obtain an M. bovis strain deleted in the mce2 genes and evaluate the effect of the mutation on the immunological profile elicited by the bacteria in cattle. We showed that the activation of CD4+ T cells in cattle inoculated with the mutant strain was equivalent to that in animals inoculated with the parental strain. Moreover, after in vitro stimulation, peripheral blood mononuclear cells from animals inoculated with the mutant produced higher levels of mRNA Th-1 cytokines than the parental strain. Therefore, these results indicate that the mce2 mutant is a promising candidate vaccine against bovine tuberculosis

Evaluation of pathogenesis caused in cattle and guinea pig by a Mycobacterium bovis strain isolated from wild boar

<p>Abstract</p> <p>Background</p> <p>In many regions of the world, wild mammals act as reservoir of <it>Mycobacterium bovis</it>, a situation that prevents the eradication of bovine tuberculosis. In order to observe whether a strain isolated from a wild boar, previously tested as highly virulent in a mice model, is also virulent in cattle, we performed cattle experimental inoculation with this strain</p> <p>Results</p> <p>Groups of Friesian calves were either infected with the wild boar strain <it>M. bovis </it>04-303 or with the bovine strain NCTC10772 as a control. We found that antigen-specific IFN-γ release in whole blood samples occurred earlier in animals infected with <it>M. bovis </it>04-303. Both <it>M. bovis </it>strains resulted in a positive skin test, with animals infected with the wild boar isolate showing a stronger response. These results and the presence of more severe organ lesions, with granuloma and pneumonic areas in cattle demonstrate that the wild boar isolate is more virulent than the NCTC10772 strain. Additionally, we tested the infectivity of the <it>M. bovis </it>strains in guinea pigs and found that <it>M. bovis </it>04-303 had the highest pathogenicity.</p> <p>Conclusions</p> <p><it>M. bovis </it>strains isolated from wild boars may be pathogenic for cattle, producing TB lesions.</p

Assessment of the Immune Responses Induced in Cattle after Inoculation of a Mycobacterium bovis Strain Deleted in Two mce2 Genes

The generation of efficient candidate vaccines against bovine tuberculosis will contribute to the control of this zoonotic disease. Rationally attenuated Mycobacterium bovis strains generated by knockout of virulence genes are promising candidate vaccines. However, to be effective, these candidate vaccines should at least maintain the immunological properties of their virulent parental M. bovis strains. Therefore, the aim of this study was to obtain an M. bovis strain deleted in the mce2 genes and evaluate the effect of the mutation on the immunological profile elicited by the bacteria in cattle. We showed that the activation of CD4+ T cells in cattle inoculated with the mutant strain was equivalent to that in animals inoculated with the parental strain. Moreover, after in vitro stimulation, peripheral blood mononuclear cells from animals inoculated with the mutant produced higher levels of mRNA Th-1 cytokines than the parental strain. Therefore, these results indicate that the mce2 mutant is a promising candidate vaccine against bovine tuberculosis

Identification of M. bovis antigens and their application in bovine tuberculosis

El objetivo fundamental del desarrollo de esta tesis es la obtención de nuevas proteínas que mejoren el diagnóstico de la tuberculosis bovina dado que el test intradérmico de tuberculina, como única prueba diagnóstica de esta enfermedad, da reacción cruzada con otras micobacterias no tuberculosas -MNT- o sea baja especificidad además de tener también baja sensibilidad. Se le suma a ello el inconveniente operativo de la necesidad de inmovilizar los animales dos veces en 72 hs. para la realización de esta prueba.Información extraída de: SIDALC (Sistema de Información y Documentación Agropecuario de las Américas)Facultad de Ciencias Veterinaria

Identification of M. bovis antigens and their application in bovine tuberculosis

El objetivo fundamental del desarrollo de esta tesis es la obtención de nuevas proteínas que mejoren el diagnóstico de la tuberculosis bovina dado que el test intradérmico de tuberculina, como única prueba diagnóstica de esta enfermedad, da reacción cruzada con otras micobacterias no tuberculosas -MNT- o sea baja especificidad además de tener también baja sensibilidad. Se le suma a ello el inconveniente operativo de la necesidad de inmovilizar los animales dos veces en 72 hs. para la realización de esta prueba.Información extraída de: SIDALC (Sistema de Información y Documentación Agropecuario de las Américas)Facultad de Ciencias Veterinaria

A protein complex from human milk enhances the activity of antibiotics and drugs against Mycobacterium tuberculosis

Mycobacterium tuberculosis, the causative agent of human tuberculosis (TB), has surpassed HIV/AIDS as the leading cause of death from a single infectious agent. The increasing occurrence of drug-resistant strains has become a major challenge for health care systems and, in some cases, has rendered TB untreatable. However, the development of new TB drugs has been plagued with high failure rates and costs. Alternative strategies to increase the efficacy of current TB treatment regimens include host-directed therapies or agents that make M. tuberculosis more susceptible to existing TB drugs. In this study, we show that HAMLET, an -lactalbumin–oleic acid complex derived from human milk, has bactericidal activity against M. tuberculosis. HAMLET consists of a micellar oleic acid core surrounded by a shell of partially denatured -lactalbumin molecules and unloads oleic acid into cells upon contact with lipid membranes. At sublethal concentrations, HAMLET potentiated a remarkably broad array of TB drugs and antibiotics against M. tuberculosis. For example, the minimal inhibitory concentrations of rifampin, bedaquiline, delamanid, and clarithromycin were decreased by 8- to 16-fold. HAMLET also killed M. tuberculosis and enhanced the efficacy of TB drugs inside macrophages, a natural habitat of M. tuberculosis. Previous studies showed that HAMLET is stable after oral delivery in mice and nontoxic in humans and that it is possible to package hydrophobic compounds in the oleic acid core of HAMLET to increase their solubility and metabolic stability. The potential of HAMLET and other liprotides as drug delivery and sensitization agents in TB chemotherapy is discussed here

Comprehensive analysis of iron utilization by Mycobacterium tuberculosis.

Iron is essential for nearly all bacterial pathogens, including Mycobacterium tuberculosis (Mtb), but is severely limited in the human host. To meet its iron needs, Mtb secretes siderophores, small molecules with high affinity for iron, and takes up iron-loaded mycobactins (MBT) and carboxymycobactins (cMBT), from the environment. Mtb is also capable of utilizing heme and hemoglobin which contain more than 70% of the iron in the human body. However, many components of these iron acquisition pathways are still unknown. In this study, a high-density transposon mutagenesis coupled with deep sequencing (TnSeq) showed that Mtb exhibits nearly opposite requirements for 165 genes in the presence of heme and hemoglobin versus MBT and cMBT as iron sources. The ESX-3 secretion system was assessed as essential for siderophore-mediated iron uptake and, surprisingly, also for heme utilization by Mtb. Predictions derived from the TnSeq analysis were validated by growth experiments with isogenic Mtb mutants. These results showed that (i) the efflux pump MmpL5 plays a dominant role in siderophore secretion, (ii) the Rv2047c protein is essential for growth of Mtb in the presence of mycobactin, and (iii) the transcriptional repressor Zur is required for heme utilization by Mtb. The novel genetic determinants of iron utilization revealed in this study will stimulate further experiments in this important area of Mtb physiology