Antibody reactivity to Mycobacterium tuberculosis-specific regions of differences 1 and regions of differences 9 proteins and peptides in rabbits, mice, and humans.

Background: The major antigens encoded by Mycobacterium tuberculosis-specific genomic regions of differences (RDs) could be useful in the development of new vaccines and/or diagnostic reagents using T-cell and/or antibody assays. In particular, RD1 proteins PE35, PPE68, ESXA, ESXB, and RD9 protein ESXV and their peptides have been identified as major T-cell antigens. However, little is known about their antibody reactivities in different mammalian species. This study aims to determine the antigen-specific antibody reactivities to the above antigens and their peptides in three different mammalian species, i.e., rabbits, mice, and humans. Methods: Sera were obtained from (i) rabbits immunized with purified recombinant proteins PE35, PPE68, ESXA, ESXB, and ESXV; (ii) mice immunized with recombinant DNA vaccine constructs of pUMVC6 and pUMVC7 containing RD1 and RD9 genes; and (iii) tuberculosis (TB) patients and healthy humans. Enzyme-linked immunosorbent assays (ELISAs) were performed with the sera to determine the antibody reactivity to purified recombinant proteins, peptide pools, and individual peptides of RD1 and RD9 proteins. Results: The ELISA results with sera from rabbits immunized with pure recombinant proteins showed positive antibody reactivity with all of the immunizing proteins and their synthetic peptide pools. Testing of the sera with individual peptides showed positive antibody reactivity with PE35 peptides P1 (aa 1-25), P2 (aa 16-40), P5 (aa 61-85), and P6 (aa 76-99); PPE68 peptides P9 (aa 121-145), P11 (aa 151-175), P14 (aa 196-220), P22 (aa 316-340), P23 (aa 331-355), and P24 (aa 346-371); all peptides (P1 to P6) of ESXA and ESXB; and ESXV peptides P1 (aa 1-25), P2 (aa 16-40), P3 (aa 31-55), P5 (aa 61-85), and P6 (aa 76-94). The sera from mice immunized with DNA vaccine constructs showed antibody reactivity to all proteins and the peptide P6 (aa 76-99) of PE35 and peptides P19 (aa 271-295) and P24 (aa 346-371) of PPE68. In humans, the peptides P11 (aa 151-175), P14 (aa 196-220), P22 (aa 316-340), P23 (aa 331-355), and P24 (aa 346-371) of PPE68 and the peptides P4 (aa 46-70), P5 (aa 61-85), and P6 (aa 76-94) of ESXV showed positive reactivity with sera from TB patients and healthy controls. Conclusion: The results demonstrate the presence of several antibody epitopes in each protein, but variations in the epitopes recognized were observed among mice, rabbits, and humans, which could be due to mammalian species differences and/or mode of antigen delivery.

Humoral immune responses in mice immunized with region of difference DNA vaccine constructs of pUMVC6 and pUMVC7.

BACKGROUND: We aimed to study the antigen-specific antibody responses in mice immunized with recombinant DNA vaccines constructs of pUMVC6 and pUMVC7, containing RD1 and RD9 genes of Mycobacterium tuberculosis. METHODS: We immunized mice with the parent and recombinant plasmids and sera were collected and tested for antibodies against pure recombinant proteins of RD1 (PE35, PPE68, EsxA, EsxB) and RD9 (EsxV), peptide mixtures of each protein and their individual peptides using enzyme-linked immunosorbent assays. The optical density (OD) values were measured at 405 nm. E/C (OD in antigen-coated wells/OD in antigen uncoated wells) were calculated, and the values of E/C>2 were considered positive. RESULTS: RD1 and RD9 antigen-specific antibodies were detected in sera of mice immunized with the recombinant DNA vaccine constructs (E/C >2.0). With respect to peptide mixtures and single peptides, only PE35mixand P6 of PE35; PPE68mixand P19, P24 of PPE68 showed antibody reactivity with sera of mice immunized with the corresponding recombinant pUMVC6 and/or pUMVC7 DNA vaccine constructs. CONCLUSIONS: The results confirm in vivo expression and immunogenicity of all the five RD1 and RD9 genes cloned in both of the DNA vaccine vectors.

Disposable Dosators for Pulmonary Insufflation of Therapeutic Agents to Small Animals.

Development of new therapeutic products requires efficacy testing in an animal model. The pulmonary route of administration can be utilized to deliver drugs locally and systemically. Evaluation of dry powder aerosols necessitates an efficient dispersion mechanism to maintain high concentrations in an exposure chamber or for direct endotracheal administration. While solutions exist to expose animals by passive inhalation to dry powder aerosols, most require masses of powder in large excess of the dose delivered. This precludes conducting early feasibility studies as insufficient drug is available at the research or early development stage to support the dose delivery requirements for conventional aerosol delivery systems. When designing an aerosol drug product, aerodynamic performance can relate directly to delivery efficiency and efficacy. Dispersion of powder into an aerosol requires energy input sufficient to overcome interparticulate forces, and particle engineering approaches can substantially improve aerosol performance. We have developed a dispersion system (dosator) which can aerosolize engineered dry powder aerosols efficiently for the purpose of direct pulmonary insufflation, dispersion into an exposure system or generation for analytical purposes.

Pharmaceutical aerosols for the treatment and prevention of tuberculosis.

Historically, pharmaceutical aerosols have been employed for the treatment of obstructive airway diseases, such as asthma and chronic obstructive pulmonary disease, but in the past decades their use has been expanded to treat lung infections associated with cystic fibrosis and other respiratory diseases. Tuberculosis (TB) is acquired after inhalation of aerosol droplets containing the bacilli from the cough of infected individuals. Even though TB affects other organs, the lungs are the primary site of infection, which makes the pulmonary route an ideal alternative route to administer vaccines or drug treatments. Optimization of formulations and delivery systems for anti-TB vaccines and drugs, as well as the proper selection of the animal model to evaluate those is of paramount importance if novel vaccines or drug treatments are to be successful. Pharmaceutical aerosols for patient use are generated from metered dose inhalers, nebulizers, and dry powder inhalers (DPIs). In addition to the advantages of providing more efficient delivery of the drug, low cost, and portability, pharmaceutical dry powder aerosols are more stable than inhalable liquid dosage forms and do not require refrigeration. Methods to manufacture dry powders in respirable sizes include micronization, spray drying, and other proprietary technologies. Inhalable dry powders are characterized in terms of their drug content, particle size, and dispersibility to ensure deposition in the appropriate lung region and effective aerosolization from the device. These methods will be illustrated as they were applied for the manufacture and characterization of powders containing anti-tubercular agents and vaccines for pulmonary administration. The influence of formulation, selection of animal model, method of aerosol generation, and administration on the efficacy demonstrated in a given study will be illustrated by the evaluation of pharmaceutical aerosols of anti-TB drugs and vaccines in guinea pigs by our group.

Whole blood assays to identify Th1 cell antigens and peptides encoded by Mycobacterium tuberculosis-specific RD1 genes.

OBJECTIVE: To identify Th1 cell-stimulating antigens/peptides encoded by the genes predicted in the Mycobacterium tuberculosis-specific genomic region of difference (RD)1, deleted in Mycobacterium bovis Bacille Calmette-Guérin(BCG), by using synthetic peptides and whole blood from tuberculosis (TB) patients. MATERIALS AND METHODS: Heparinized peripheral blood was obtained from culture-proven pulmonary TB patients (n = 16) attending the Chest Disease Hospital, Kuwait. Whole blood was diluted with tissue culture medium RPMI-1640 and tested for Th1 cell stimulation using antigen-induced proliferation and interferon-gamma (IFN-gamma) secretion assays. The antigens included a peptide pool of 220 peptides covering the sequence of 12 open reading frames (ORFs) of RD1 (RD1(mix)), peptide pools of RD1 ORF5 (ORF5(mix)), ORF6 (ORF6(mix)) and ORF7 (ORF7(mix)), and individual peptides of ORF6 (P6.1-P6.6) and ORF7 (P7.1-P7.6). M. tuberculosis culture filtrate, cell walls and whole-cell M. bovis BCG were used as complex mycobacterial antigens. The results obtained with different antigens and peptides were statistically analyzed for significant differences using Z test. RESULTS: The complex mycobacterial antigens (culture filtrate, cell walls and M.bovis BCG) and RD1(mix) induced comparable (p > 0.05) positive antigen-induced proliferation and IFN-gamma responses with whole blood from TB patients. However, the positive IFN-gamma responses induced by ORF6(mix) and ORF7(mix) were higher than ORF5(mix). Among the individual peptides, P6.4 and P7.1 of ORF6 and ORF7, respectively, induced the highest IFN-gamma responses, suggesting that these peptides represented the immunodominant Th1 cell epitopes of RD1 ORF6 and ORF7 in the patients tested. CONCLUSION: The whole blood assays with synthetic peptides are useful to identify Th1 cell antigens/peptides encoded by genes located in M. tuberculosis-specific genomic regions.