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.

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.

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.

Recognition of a multiple antigen peptide containing sequence from mimotope of the dengue type 3 virus NS4B protein by human antibodies

Objective: To evaluate the recognition of NS4B mimotope, as multiple antigen peptide (MAP), by dengue antibodies presents in serum samples from patients with different serotype infections. Methods: A MAP containing mimotope sequence was synthesized and used to evaluate the recognition of NS4B mimotope as MAP by a panel of 66 human sera from dengue cases by an indirect ELISA assay. Results: The MAP differentiated between sera from dengue viruses infected patients and sera from healthy individuals and the best reactivity was shown by serum from dengue type 3 virus patients. The recognition was more intense with serum from patients with secondary infection. Conclusions: The findings suggest the potential use of NS4B mimotope on the development of a multi-epitope diagnostic tool. These results are important for further immunogenicity studies.

Recognition of a multiple antigen peptide containing sequence from mimotope of the dengue type 3 virus NS4B protein by human antibodies

OBJECTIVE@#To evaluate the recognition of NS4B mimotope, as multiple antigen peptide (MAP), by dengue antibodies presents in serum samples from patients with different serotype infections.@*METHODS@#A MAP containing mimotope sequence was synthesized and used to evaluate the recognition of NS4B mimotope as MAP by a panel of 66 human sera from dengue cases by an indirect ELISA assay.@*RESULTS@#The MAP differentiated between sera from dengue viruses infected patients and sera from healthy individuals and the best reactivity was shown by serum from dengue type 3 virus patients. The recognition was more intense with serum from patients with secondary infection.@*CONCLUSIONS@#The findings suggest the potential use of NS4B mimotope on the development of a multi-epitope diagnostic tool. These results are important for further immunogenicity studies.

Selection of phage-displayed human antibody fragments specific for CD1b presenting the Mycobacterium tuberculosis glycolipid Ac[2]SGL

Objective/background: the development of new tools capable of targeting Mycobacterium tuberculosis [Mtb]-infected cells have potential applications in diagnosis, treatment, and prevention of tuberculosis. In Mtb-infected cells, CD1b molecules present Mtb lipids to the immune system [Mtb lipid-CD1b complexes]. Because of the lack of CD1b polymorphism, specific Mtb lipid-CD1b complexes could be considered as universal Mtb infection markers. 2-Stearoyl-3-hydroxyphthioceranoyl-2' -sulfate-alpha-alpha'-o-trehalose [Ac[2]SGL] is specific for Mtb, and is not present in other mycobacterial species. The CD1b-Ac[2]SGL complexes are expressed on the surface of human cells infected with Mtb. The aim of this study was to generate ligands capable of binding these CD1b-Ac[2]SGL complexes

Methods: a synthetic human scFv phage antibody library was used to select phage-displayed antibody fragments that recognized CD1b-Ac[2]SGL using CD1btransfected THP-1 cells loaded with Ac[2]SGL

Results: one clone, D11- a single, light-variable domain [kappa] antibody [dAb[kappa]11]-showed high relative binding to the Ac[2]SGL-CD1b complex

Conclusion: a ligand recognizing the Ac[2]SGL- CD1b complex was obtained, which is a potential candidate to be further tested for diagnostic and therapeutic applications

Cellular and humoral immunogenicity of recombinant Mycobacterium smegmatis expressing Ag85B epitopes in mice

Objective/background: The search for new vaccines more efficacious than bacille Calmette-Guerin for tuberculosis prevention is of paramount importance for the control of the disease. The expression of Mycobacterium tuberculosis antigens in Mycobacterium smegmatis is one of the current strategies for the development of new-generation vaccines against tuberculosis. The objective of this study was to evaluate the immunogenicity in mice of M. smegmatis expressing epitopes from Ag85B antigen

Methods: M. smegmatis expressing three T cell epitopes from M. tuberculosis Ag85B [P21, P26, and P53] was constructed [rMs064]. rMs064 was used to immunize BALB/C mice for immunogenicity evaluation. The present study investigates the capacity of rMs064 to induce specific cellular and humoral immune responses against the expressed epitopes. Cytokine production upon stimulation with Ag85B peptides and specific total immunoglobulin G and immunoglobulin G subclasses were determined

Results: The results showed a significant production of interleukin-12 and interleukin-23 when splenocytes were stimulated with P21, P26, and P53 peptides, and interferon-gamma after stimulation with P21 in animals immunized with rMs064 compared with controls. The total immunoglobulin G and its subclasses showed significant increases against the Ag85B epitapes in the sera of rMs064-immunized mice compared with the control groups

Conclusion: The results of this study support the future evaluation of rMs064 as a vaccine candidate against tuberculosis in challenge experiments

Histopathological Study of the Lungs of Mice Receiving Human Secretory IgA and Challenged with Mycobacterium tuberculosis

Background: Humoral and cellular immune responses are associated with protection against extracellular and intracellular pathogens, respectively. In the present study, we evaluated the effect of receiving human secretory immunoglobulin A (hsIgA) on the histopathology of the lungs of mice challenged with virulent Mycobacterium tuberculosis. Methods: The hsIgA was purified from human colostrum and administered to Balb/c mice by the intranasal route prior to infection with M. tuberculosis or in a pre-incubated formulation with mycobacteria, with the principal aim to study its effect on qualitative pulmonary histopathology. Results: The intranasal administration of hsIgA and the pre-incubation of mycobacteria with this preparation was associated with the presence of organised granulomas with signs of immune activation and histological features related to efficient disease control. This effect was highly evident during the late stage of infection (60 days), as demonstrated by numerous organised granulomas with numerous activated macrophages in the lungs of treated mice. Conclusion: The administration of hsIgA to mice before intratracheal infection with M. tuberculosis or the pre-incubation of the bacteria with the antibody formulation induced the formation of well-organised granulomas and inflammatory lesions in lungs compared with non-treated animals which correlates with the protective effect already demonstrated by these antibody formulations.

The Importance of Animal Models in Tuberculosis Vaccine Development

Research, development, and production of vaccines are still highly dependent on the use of animal models in the various evaluation steps. Despite this fact, there are strong interests and ongoing efforts to reduce the use of animals in vaccine development. Tuberculosis vaccine development is one important example of the complexities involved in the use of animal models for the production of new vaccines. This review summarises some of the general aspects related with the use of animals in vaccine research and production, as well as achievements and challenges towards the rational use of animals, particularly in the case of tuberculosis vaccine development.

Identification of Dengue-specific B-Cell Epitopes by Phage-display Random Peptide Library

Background: Dengue is the most important human viral disease transmitted by arthropod vectors. The availability of random peptide libraries (RPL) displayed on phage has provided a powerful tool for selecting sequences that mimic epitopes from microorganisms that are useful for diagnostic and vaccine development purposes. In this paper, we describe peptides that resemble the antigenic structure of B-cell epitopes of dengue virus identified from a phage-peptide library using human sera containing polyclonal antibodies against dengue virus. Materials and Methods: Eighteen phage clones were isolated from the phage-display peptide library, J404, by affinity selection using human antisera against dengue virus type 3. These clones were tested for reactivity by ELISA with a panel of hyperimmune ascitic fluids (HAFs) containing antibodies either against all four dengue serotypes, West Nile virus (WNV) or Eastern equine encephalitis virus (EEEV) with control ascitic fluid (NAF) used as a negative control. Results: Eight clones were recognized by HAFs against the four dengue serotypes, of which four significantly inhibited binding of anti-dengue antibodies to the virus. Two peptides with similar sequences to regions of NS3 and NS4B non-structural dengue virus proteins were identified. Conclusion: Our results suggest that these peptides could be used for the development of diagnostic tools for the detection of dengue virus infection and for a potential vaccine against this pathogen.

Respuesta humoral específica en ratones Balb/c inoculados con una librería genómica de expresión de Trypanosoma cruzi / Specific humoral response in Balb/c mice inoculated with a genome library of expression of Trypanosoma cruzi

A genomic expression library of Trypanosoma cruzi (T. cruzi) was made using plasmid pcDNA3 as a vector, with which male mice from the Balb/c isogenic line were intramuscullary inoculated. It was used a positive control group that was administered soluble antigens of T. cruzi. Other 2 groups received genomic and plasmid DNA, respectively. One group was not immunized. Weekly blood samples were obtained from all the animals until the fourth week and 2 weeks after reimmunization to study the response of specific antibodies against the microorganism antigens by an indirect immunoenzymatic assay (ELISA). It was observed a significant increase of specific antibodies in the animals reimmunized with 50 micrograms of the library, as well as in the group immunized with soluble antigens of T. cruzi.