Liposomes as immunological adjuvants and delivery systems in the development of tuberculosis vaccine: A review

Liposomes are phospholipid bilayer vesicles, which are biocompatible, biodegradable and nontoxic vehicles suitable for numerous drug and gene delivery applications. In this review, we discuss the prospect of using liposome technology in the development of a vaccine for tuberculosis. Tuberculosis remains an important health problem that requires the development of an effective vaccine, especially since the only approved vaccine for it continues to be the Bacille Calmette-Geurin (BCG) one developed 100 years ago. This review focuses on the different applications of liposomes toward achieving this goal. Numerous liposomal formulations showing prospect in the research stage and in clinical trials are discussed.

Mycobacterium tuberculosis recombinant protein Rv2626c expressed in Streptomyces lividans. Physico-chemical and Immunological characterization as potential vaccine antigen

Mycobacterium tuberculosis (Mtb) is a leading cause of death globally. Latent tuberculosis infection threatens 1.7 billion people. Mtb latency is mediated by a group of proteins, mainly coded by the Dormancy Safety Regulator (DosR). The protein Rv2626c is the strongest regulated member of this operon. Previous results, including ours, indicate a strong potential of Rv2626c as antigen in a new multiple tuberculosis vaccine. Objectives of this study were to purify the rRv2626c protein and characterize it physico-chemically and immunologically. The purified protein migrates as a sole band after a non-reductive PAGE-silver staining. Under reductive conditions, the dimer isoform appearing at 30.9 kDa prevails over the monomer 15.6 kDa. Mass spectrometry corroborates electrophoresis results regarding dimer molecular weight, of approximately 32 kDa. Six of its digested peptides matched those of HRP-1 protein (Rv2626c) of Mtb whereas 92.1 percent of its amino acid sequence contains three mutations and the addition of an amino acid. With respect to native Mtb protein, 12 of the 13 main epitopes are conserved. Antigenicity was corroborated in volunteers, the antibody responses were significantly higher in a number of infected tuberculosis patients in comparison to healthy Mantoux negative donors as well as in mice immunized with reference Rv2626c, while the immune identification pattern was as expected. The purified protein was able to elicit strong immune response in mice and the resulting antibodies recognized the reference Rv2626c protein. Lastly, the productive specific yield of the Streptomyces lividans strain is sustainable. Taking these results altogether, corroborates our rRv2626c as a promising candidate as antigen for new tuberculosis vaccine formulations(AU)

Mycobacterium tuberculosis (Mtb) es una de las principales causas de muerte globalmente, la tuberculosis latente amenaza a 1,7 mil millones de personas. En combinación con el VIH-SIDA y otras enfermedades, la tuberculosis puede ser reactivada. La latencia de Mtb está mediada por un grupo de proteínas, principalmente codificadas por el Regulador de Seguridad de Latencia (DosR). La proteína Rv2626c es el miembro más fuertemente regulado de este operón. Los resultados previos, incluidos los nuestros, indican una gran potencialidad de Rv2626c como antígeno en una nueva vacuna múltiple contra la tuberculosis. Los objetivos de este estudio fueron purificar la proteína Rv2626c y caracterizarla fisicoquímica e inmunológicamente. La proteína purificada migra como una banda única después de PAGE con tinción de plata en condiciones no reductoras. En condiciones reductoras, el dímero, de 30,9 kDa, es la isoforma prevaleciente sobre el monómero, de 15,6 kDa. La espectrometría de masas corrobora el peso molecular del dímero, de aproximadamente 32 kDa. Seis de sus péptidos digeridos coincidieron con los de la proteína Rv2626c de Mtb, mientras que se confirmó coincidencia del 92,1 por ciento de su secuencia de aminoácidos, detectándose tres mutaciones y la adición de un aminoácido. Con respecto a la proteína Mtb nativa, se conservan 12 de los 13 epítopes principales. La antigenicidad se corroboró en voluntarios, las respuestas de anticuerpos fueron significativamente mayores en un número de pacientes infectados con tuberculosis en comparación con los donantes negativos de Mantoux sanos, así como en ratones inmunizados con la referencia Rv2626c, mientras que el patrón de identificación inmune fue el esperado. La proteína purificada fue capaz de provocar una fuerte respuesta inmune en ratones y los anticuerpos resultantes reconocieron la proteína de referencia Rv2626c. Por último, el rendimiento productivo específico de la cepa de Streptomyces lividans es sostenible. Tomando estos resultados en conjunto, corrobora nuestra rRv2626c como un candidato prometedor como antígeno para nuevas formulaciones de vacunas contra la tuberculosis(AU)

Impact of Bacille Calmette-Guérin revaccination on serum IgE levels in a randomized controlled trial

Abstract INTRODUCTION: Bacille Calmette-Guérin (BCG) downmodulates allergen-specific IgE levels and prevents other atopic responses in experimental models but fails to protect against respiratory allergies. Human responsiveness to BCG is variable and may interfere with protection. METHODS: Multivariate models were evaluated to test the possible effect of responsiveness (assessed by IFN-γ production) to BCG revaccination on the modulation of total and allergen-specific serum IgE levels in healthy volunteers participating in a randomized controlled trial. RESULTS: Serum total or Derp-specific IgE levels did not change regardless of the increase in IFN-γ levels. CONCLUSIONS: BCG responsiveness does not affect protection against atopy.

Therapeutic evaluation of antibiotics combined with recombinant tuberculosis vaccine AEC/BC02 in a guinea pig model of Mycobacterium tuberculosis infection / 中华微生物学和免疫学杂志

Objective To evaluate the therapeutic effect of antibiotics combined with recombinant tuberculosis vaccine AEC/BC02 on Mycobacterium tuberculosis infection in guinea pigs. Methods Two weeks after guinea pigs were challenged subcutaneously with a high dose of Mycobacterium tuberculosis,the guinea pigs with the positive skin test responses to the recombinant ESAT6-CFP10 allergen were randomly di-vided into four groups:normal saline (NS),AEC/BC02,antibiotics and antibiotics+AEC/BC02. In antibiotics+AEC/BC02 group,guinea pigs firstly received isoniazid ( INH) and rifapentine ( RFT) treatment once a week for a total of three times,and then were immunized with a single dose of AEC/BC02 vaccine six times at 10-day intervals. Guinea pigs in AEC/BC02 and antibiotics groups were respectively vaccinated with AEC/BC02 vaccine and given INH and RFT treatment at the same dose and frequency as given to antibiotics+ AEC/BC02 group. Thirteen weeks after challenge,all guinea pigs were sacrificed for necropsy. Results The gross pathological scores of NS,AEC/BC02,antibiotics and antibiotics+AEC/BC02 groups were 83±8,77± 22,45±28 and 19±14,respectively. Antibiotics+AEC/BC02 group had a significantly lower gross pathological score than antibiotics,AEC/BC02 and NS groups (P<0. 05,P<0. 01,P<0. 01,respectively). Moreover,the gross pathological scores of antibiotics and AEC/BC02 groups were significantly decreased as compared with that of NS group (both P<0. 01). However,there was no significant difference between AEC/BC02 and NS groups. The spleen bacterial load of antibiotics+AEC/BC02 group was (2. 50±1. 26) lg CFU,which was sig-nificantly lower than those of NS [(4. 92+0. 52) lg CFU],AEC/BC02 [(4. 78+0. 84) lg CFU] and antibi-otics [(4. 39+0. 50) lg CFU] groups (P<0. 01). Compared with NS group,antibiotic and AEC/BC02 groups showed no significant difference in spleen bacterial load. Histopathological changes indicated different levels of granulomatous lesions appeared in lung tissues of all groups and the most severe change was ob-served in AEC/BC02 group,followed by that in NS,antibiotics and antibiotics+AEC/BC02 groups. Conclu-sion INH and RFT treatment in combination with AEC/BC02 vaccine in the treatment of guinea pigs with Mycobacterium tuberculosis infection was superior to either treatment alone as it significantly alleviated organ lesions and lowered the bacterial loads in spleen and lung.