Evaluation of the potential of Mycobacterium smegmatis as vaccine Candidate against tuberculosis by in silico and in vivo studies

In this study, we scanned multiple published databases of gene expression in vivo of M. tuberculosis at different phases of infection in animals and humans, to select 38 proteins that are highly expressed in the active, latent and reactivation phases. The selected proteins were predicted for T and B epitopes. For each proteins, the regions containing T and B epitopes were selected at the same time to look for identical epitopes on M. smegmatis based on sequence alignments. Preliminary studies of humoral immunogenicity and cross-reactivity with M. tuberculosis in mice using two M. smegmatis-derived experimental vaccines were carried out, demonstrating the immunogenicity of M. smegmatis proteoliposomes and the recognition of M. tuberculosis proteins by the sera of animals immunized with this vaccine candidate. The conjunction of in silico and in vivo studies suggested the potential for future evaluation of M. smegmatis as vaccine candidate against tuberculosis using different strategie

Estandarización de un ensayo inmunoenzimático para la cuantificación de anticuerpos IgG contra el antígeno de superficie recombinante del virus de la Hepatitis B inducidos en conejos New Zealand

La infección por el virus de la Hepatitis B está extendida por todo el mundo. Actualmente, miles de personas mueren a causa de este virus, por lo que es una necesidad desarrollar vacunas que protejan contra este patógeno. Existen vacunas basadas en el antígeno recombinante de superficie del virus de la Hepatitis B donde la eficacia protectora de la vacunación contra el virus está directamente relacionada con la inducción de anticuerpos contra el antígeno de superficie. Por tal razón, es muy importante de contar con una técnica sensible, específica y precisa que sea capaz de detectar niveles de anticuerpos en sueros. En este trabajo se representan los resultados del proceso de estandarización de un ELISA indirecto de cuantificación que se desarrolló con sueros de conejos New Zealand inmunizados con la vacuna comercial Heberpenta-L y una vacuna experimental combinada. En los cuales se determinó la concentración óptima de recubrimiento, el intervalo y linealidad de la curva, la precisión intra e interensayo, la especificidad y el límite de detección. La curva de calibración, generada con un estándar interno, presentó un buen ajuste lineal y un intervalo entre las diluciones 1/200 a 1/12800. Los coeficientes de variación en los ensayos de precisión estuvieron en los intervalos establecidos para cada uno (≤10%, ≤20% respectivamente). El ensayo presentó una especificidad óptima y se determinó el valor de corte que fue de 18,086 UA/mL. Estos resultados avalan el empleo de esta técnica en los laboratorios del Instituto Finlay de vacunas para la evaluación preclínica de nuevos candidatos vacunales combinados que protejan contra la Hepatitis B

Specific and cross-reactive immune response against Mycobacterium tuberculosis antigens in mice immunized with proteoliposomes from Mycobacterium bovis BCG

Objective: To characterize the immunogenicity and the induction of cross-reactive responses against Mycobacterium tuberculosis (M. tuberculosis) of a proteoliposome (PL) from Mycobacterium bovis Bacillus Calmette–Guérin (BCG) with and without alum hydroxide (AL) as adjuvant (PLBCG-AL and PLBCG, respectively) in BALB/c mice. Methods: BALB/c mice were inoculated with phosphate buffer solution, BCG, PLBCG and PLBCG-AL. The humoral immunogenicity was determined by ELISA [immunoglobulin G (IgG), IgG1 and IgG2a] and the cellular immunogenicity was evaluated in vivo by delayed type hypersensitivity. The humoral cross-reactive response against M. tuberculosis was determined by Western blot. Results: Sera from animals immunized with PLBCG-AL and PLBCG showed significant increase in specific total IgG and IgG1 antibodies and the presence of cross-reactive antibodies against M. tuberculosis antigens, which were more intense with the use of alum as adjuvant. Mice immunized with PLBCG and PLBCG-AL also showed a specific cellular response in vivo. Conclusions: The cellular and humoral immunogenicity of PLBCG and the capacity to induce cross-reactive responses against M. tuberculosis is in agreement with the protective capacity previously demonstrated by this vaccine candidate and supports the continuation of its evaluation in further stages

Protective Effect of a Lipid-Based Preparation from Mycobacterium smegmatis in a Murine Model of Progressive Pulmonary Tuberculosis

A more effective vaccine against tuberculosis (TB) is urgently needed. Based on its high genetic homology with Mycobacterium tuberculosis (Mtb), the nonpathogenic mycobacteria, Mycobacterium smegmatis (Ms), could be an attractive source of potential antigens to be included in such a vaccine. We evaluated the capability of lipid-based preparations obtained from Ms to provide a protective response in Balb/c mice after challenge with Mtb H37Rv strain. The intratracheal model of progressive pulmonary TB was used to assess the level of protection in terms of bacterial load as well as the pathological changes in the lungs of immunized Balb/c mice following challenge with Mtb. Mice immunized with the lipid-based preparation from Ms either adjuvanted with Alum (LMs-AL) or nonadjuvanted (LMs) showed significant reductions in bacterial load (P<0.01) compared to the negative control group (animals immunized with phosphate buffered saline (PBS)). Both lipid formulations showed the same level of protection as Bacille Calmette and Guerin (BCG). Regarding the pathologic changes in the lungs, mice immunized with both lipid formulations showed less pneumonic area when compared with the PBS group (P<0.01) and showed similar results compared with the BCG group. These findings suggest the potential of LMs as a promising vaccine candidate against TB

Passive administration of purified secretory IgA from human colostrum induces protection against <it>Mycobacterium tuberculosis</it> in a murine model of progressive pulmonary infection

<p>Abstract</p> <p>Background</p> <p>Immunoglobulin A is the most abundant isotype in secretions from mucosal surfaces of the gastrointestinal, respiratory and genitourinary tracts and in external secretions such as colostrum, breast milk, tears and saliva. The high concentration of human secretory IgA (hsIgA) in human colostrum strongly suggests that it should play an important role in the passive immune protection against gastrointestinal and respiratory infections.</p> <p>Materials and methods</p> <p>Human secretory IgA was purified from colostrum. The reactivity of hsIgA against mycobacterial antigens and its protective capacity against mycobacterial infection was evaluated.</p> <p>Results</p> <p>The passive administration of hsIgA reduces the pneumonic area before challenge with <it>M.</it> tuberculosis. The intratracheal administration of <it>M. tuberculosis</it> preincubated with hsIgA to mice greatly reduced the bacterial load in the lungs and diminished lung tissue injury.</p> <p>Conclusions</p> <p>HsIgA purified from colostrum protects against <it>M. tuberculosis</it> infection in an experimental mouse model.</p