Escheriosome-mediated delivery of recombinant ribosomal L7/L12 protein confers protection against murine brucellosis

Liposomes like advanced drug carriers: from fundamentals to pharmaceutical applications

AIMS

There are around 24 distinct lipid vesicles described in the literature that are similar to vesicular systems such as liposomes. Liposome-like structures are formed by combining certain amphiphilic lipids with a suitable stabiliser. Since their discovery and classification, self-assembled liposome-like structures as active drug delivery vehicles captured researchers' curiosity.

METHODOLOGY

This comprehensive study included an in-depth literature search using electronic databases such as PubMed, ScienceDirect and Google Scholar, focusing on studies on liposome and liposomes like structure, discussed in literature till 2024, their sizes, benefits, drawback, method of preparation, characterisation and pharmaceutical applications.

RESULTS

Pharmacosomes, cubosomes, ethosomes, transethosomes, and genosomes, all liposome-like structures, have the most potential due to their smaller size with high loading capacity, ease of absorption, and ability to treat inflammatory illnesses. Genosomes are futuristic because of its affinity for DNA/gene transport, which is an area of focus in today's treatments.

CONCLUSION

This review will critically analyse the composition, preparation procedures, drug encapsulating technologies, drug loading, release mechanism, and related applications of all liposome-like structures, highlighting their potential benefits with enhanced efficacy over each other and over traditional carriers by paving the way for exploring novel drug delivery systems in the Pharma industry.

Self-Assembled Proteinaceous Nanoparticles for Co-Delivery of Antigens and Cytosine Phosphoguanine (CpG) Adjuvants: Implications for Nanovaccines

Nanotechnology has developed rapidly, giving rise to "nanovaccinology". In particular, protein-based nanocarriers have gained widespread attention because of their excellent biocompatibility. As the development of flexible and rapid vaccines is challenging, modular extensible nanoparticles are urgently needed. In this study, a multifunctional nanocarrier capable of delivering various biomolecules (including polysaccharides, proteins, and nucleic acids) was designed by fusing the cholera toxin B subunit with streptavidin. Then, the nanocarrier was used to prepare a bioconjugate nanovaccine against S. flexneri by co-delivery of antigens and CpG adjuvants. Subsequent experimental results indicated that the nanovaccine with multiple components could stimulate both adaptive and innate immunity. Moreover, combining nanocarriers and CpG adjuvants with glycan antigens could improve the survival of vaccinated mice during the interval of two vaccination injections. The multifunctional nanocarrier and the design strategy demonstrated in this study could be utilized in the development of many other nanovaccines against infectious diseases.

Multicompartment systems: A putative carrier for combined drug delivery and targeting

In this review, we discuss recent developments in multicompartment systems commonly referred to as vesosomes, as well as their method of preparation, surface modifications, and clinical potential. Vesosomal systems are able to entrap more than one drug moiety and can be customized for site-specific delivery. We focus in particular on the possible reticuloendothelial system (RES) - mediated accumulation of vesosomes, and their application in tumor targeting, as areas for further investigation.

Prophylactic vaccine delivery systems against epidemic infectious diseases

Prophylactic vaccines have evolved from traditional whole-cell vaccines to safer subunit vaccines. However, subunit vaccines still face problems, such as poor immunogenicity and low efficiency, while traditional adjuvants are usually unable to meet specific response needs. Advanced delivery vectors are important to overcome these barriers; they have favorable safety and effectiveness, tunable properties, precise location, and immunomodulatory capabilities. Nevertheless, there has been no systematic summary of the delivery systems to cover a wide range of infectious pathogens. We herein summarized and compared the delivery systems for major or epidemic infectious diseases caused by bacteria, viruses, fungi, and parasites. We also included the newly licensed vaccines (e.g., COVID-19 vaccines) and those close to licensure. Furthermore, we highlighted advanced delivery systems with high efficiency, cross-protection, or long-term protection against epidemic pathogens, and we put forward prospects and thoughts on the development of future prophylactic vaccines.

Hypothesis: Designation of Liposomal Scavenger System for Fighting against 2019-nCoV

2019 novel coronavirus (2019-nCoV), also known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or COVID-19 virus, is a member of the family Coronaviridae, which is responsible for the current pandemic of disease COVID-19. It is the seventh member of the family Coronaviridae, which infects humans, after 229E, OC43, NL63, HKU1, SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV). Fever, dry cough and severe pneumonia are seen as common symptoms at the early stages of COVID-19. Some cases progress to acute respiratory stress syndrome, septic shock, organ failure, and death. The development of an effective treatment or vaccination for treating or preventing this lethal condition is an urgent need in order to fight this crisis. Up to now, some effective vaccines with different efficacy profiles have been introduced. Herein, we have theoretically designed a scavenger system for gathering 2019-nCoVs, breaking them, and re-introducing them to the immune system.

Lipid nanovesicles for biomedical applications: 'What is in a name'?

Vesicles, generally defined as self-assembled structures formed by single or multiple concentric bilayers that surround an aqueous core, have been widely used for biomedical applications. They can either occur naturally (e.g. exosomes) or be produced artificially and range from the micrometric scale to the nanoscale. One the most well-known vesicle is the liposome, largely employed as a drug delivery nanocarrier. Liposomes have been modified along the years to improve physicochemical and biological features, resulting in long-circulating, ligand-targeted and stimuli-responsive liposomes, among others. In this process, new nomenclatures were reported in an extensive literature. In many instances, the new names suggest the emergence of a new nanocarrier, which have caused confusion as to whether the vesicles are indeed new entities or could simply be considered modified liposomes. Herein, we discussed the extensive nomenclature of vesicles based on the suffix "some" that are employed for drug delivery and composed of various types and proportions of lipids and others amphiphilic compounds. New names have most often been selected based on changes of vesicle lipid composition, but the payload, structural complexity (e.g. multicompartment) and new/improved proprieties (e.g. elasticity) have also inspired new vesicle names. Based on this discussion, we suggested a rational classification for vesicles.

Design of a Multi-epitope Vaccine Against Acinetobacter baumannii Using Immunoinformatics Approach

Acinetobacter baumannii is one of the most successful pathogens causing nosocomial infections and has significantly multidrug-resistant. So far, there are no certain treatments to protect against infection with A. baumannii, therefore an effective A. baumannii vaccine needed. The purpose of this study was to predict antigenic epitopes of CarO protein for designing the A. baumannii vaccine using immunoinformatics analysis. CarO protein is one of the most important factors in the resistance against the antibiotic Carbapenem. In this study, T and B-cell epitopes of CarO protein were predicted and screened based on the antigenicity, toxicity, allergenicity features. The epitopes were linked by suitable linkers. Four different adjuvants were attached to the vaccine constructs which among them, vaccine construct 3 was chosen to predict the secondary and the 3D structure of the vaccine. The refinement process was performed to improve the quality of the 3D model structure; the validation process is performed using the Ramachandran plot and ProSA z-score. The designed vaccine's binding affinity to six various HLA molecules and TLR 2 and TLR4 were evaluated by molecular docking. Finally, in silico gene cloning was performed in the pET28a (+) vector. The findings suggest that the vaccine may be a promising vaccine to prevent A. baumannii infection.

Comparison of transcriptional change of B. melitensis M5-90 after macrophage infection highlights the role of ribosome gene L31 in virulence

Brucella, a facultative intracellular bacterium, can survive and replicate in various cell types such as epithelial cell, fibroblasts and macrophage. Macrophage is the most important sites for the survival of Brucella in vivo. The mechanisms of pathogenesis are difficult to address, since the unknown virulence genes are still exist. RNA-seq is available to study transcriptional changes that occur during disease as a way to identify important virulence-related genes. Here we described and analyzed the transcriptional change of avirulent strain Brucella melitensis M5-90 (B. melitensis M5-90) during macrophage infection using RNA-seq technology. We detected 601 significant changed genes of which 428 were upregulated after infection. The upregulated gene L31 which involved in ribosome KEGG pathway was selected to illustrate its effect on virulence in a vaccine strain B. melitensis M5-90 and a virulent strain B. melitensis M28. Deletion of L31 significant attenuates the spleen colonization in model of M5-90 or M28 infection mouse at 7, 21 and 35 days post-infection (P < 0.05). We further examine the role of L31 in a macrophage cell infection model, and the result showed a significant reduction of intracellular M28ΔL31 cells at 48 h post-infection (P < 0.001). In total, our study provided a view of transcriptional landscape of B. melitensis M5-90 intracellular, and found L31 gene is required for the full virulence of B. melitensis.

Mucosal delivery of live Lactococcus lactis expressing functionally active JlpA antigen induces potent local immune response and prevent enteric colonization of Campylobacter jejuni in chickens

Successful colonization of the mucosal epithelial cells is the key early step for Campylobacter jejuni (C. jejuni) pathogenesis in humans. A set of Surface Exposed Colonization Proteins (SECPs) are known to take leading role in bacterial adhesion and subsequent host pathogenesis. Among the major SECPs, the constitutively expressed C. jejuni surface lipoprotein Jejuni lipoprotein A (JlpA), interacts with intestinal heat shock protein 90α (Hsp90α) and contributes in disease progression by triggering pro-inflammatory responses via activation of NF-κB and p38 MAP kinase pathways. In addition to its ability to express on the surface, high sequence conservation of JlpA protein among different Campylobacter spp make it a suitable vaccine target against C. jejuni. Given that chickens are the primary source for C. jejuni infection in humans and persistent cecal colonization significantly contribute in pathogen transmission, we explicitly used chickens as a model to test the immune-protective efficacy of JlpA protein. Taking into account that gastro-intestinal tract is the major site for C. jejuni colonization, we chose to use mucosal (intragastric) route as mode for JlpA antigen delivery. To deliver JlpA via mucosal route, we engineered a food grade Lactic acid producing bacteria, Lactococcus lactis (L. lactis) to express functionally active JlpA protein in the surface. Further, we demonstrated its ability to substantially improve the antigen specific local immune responses in the intestine along with significant immune-protection against enteric colonization of C. jejuni in chickens.

Meta-Analysis and Advancement of Brucellosis Vaccinology

Background/Objectives

In spite of all the research effort for developing new vaccines against brucellosis, it remains unclear whether these new vaccine technologies will in fact become widely used. The goal of this study was to perform a meta-analysis to identify parameters that influence vaccine efficacy as well as a descriptive analysis on how the field of Brucella vaccinology is advancing concerning type of vaccine, improvement of protection on animal models over time, and factors that may affect protection in the mouse model.

Methods

A total of 117 publications that met the criteria were selected for inclusion in this study, with a total of 782 individual experiments analyzed.

Results

Attenuated (n = 221), inactivated (n = 66) and mutant (n = 102) vaccines provided median protection index above 2, whereas subunit (n = 287), DNA (n = 68), and vectored (n = 38) vaccines provided protection indexes lower than 2. When all categories of experimental vaccines are analyzed together, the trend line clearly demonstrates that there was no improvement of the protection indexes over the past 30 years, with a low negative and non significant linear coefficient. A meta-regression model was developed including all vaccine categories (attenuated, DNA, inactivated, mutant, subunit, and vectored) considering the protection index as a dependent variable and the other parameters (mouse strain, route of vaccination, number of vaccinations, use of adjuvant, challenge Brucella species) as independent variables. Some of these variables influenced the expected protection index of experimental vaccines against Brucella spp. in the mouse model.

Conclusion

In spite of the large number of publication over the past 30 years, our results indicate that there is not clear trend to improve the protective potential of these experimental vaccines.

Identification of a protective protein from stationary-phase exoproteome of Brucella abortus

Brucellosis is a worldwide zoonotic disease. No Brucella vaccine is available for use in humans, and existing animal vaccines have limitations. To search the putative vaccine candidates, we studied the exoproteome of Brucella abortus NCTC 10093 using 2-DE-MS approach. Twenty-six proteins were identified using MALDI-TOF/TOF tandem mass spectrometry. Outer membrane protein 25, d-galactose periplasmic-binding protein, oligopeptide ABC transporter protein and isopropylmalate synthase were found to be the most abundant proteins. Most proteins (6, 23%) were predicted to be involved in amino acid transport and metabolism followed by carbohydrate transport and metabolism (4, 15%). Outer membrane protein 25, Omp2b porin and one hypothetical protein were predicted as outer membrane proteins. In addition, Omp28, Omp31 and one ribosomal protein (L9) were also identified. The ribosomal protein L9 was produced as a recombinant protein and was studied in mouse model for vaccine potential. It was found to be immunogenic in terms of generating serum antibody response and release of IFN-γ from mice spleen cells. Recombinant L9-immunized mice were protected against challenge with virulent B. abortus strain 544, suggesting usefulness of ribosomal protein L9 as a good vaccine candidate against brucellosis.

Anticancer efficacy of a novel propofol-linoleic acid-loaded escheriosomal formulation against murine hepatocellular carcinoma

AIM

The preparation and characterization of a novel escheriosomal nanoparticle formulation of a potent anticancer conjugate, 2,6-diisopropylphenol-linoleic acid (2,6P-LA), and evaluation of its anticancer efficacy against diethyl nitrosamine-induced hepatocellular carcinoma (HCC) in BALB/c mice.

MATERIALS & METHODS

Escheriosomized 2,6P-LA nanoparticles were characterized for size, zeta-potential, entrapment efficiency, release kinetics and in vivo toxicity. Their anticancer potential was evaluated on the basis of survival, DNA fragmentation, caspase-3 activation, western blot analysis of apoptotic factors and histopathological changes in hepatocytes of treated animals.

RESULTS

The escheriosomized 2,6P-LA nanoparticles exhibited low toxicity, biocompatibility and bioavailability. As revealed by apoptosis induction, survival rate, expression profiles of Bax, Bcl-2 and caspase-9, escheriosomized 2,6P-LA nanoparticles were more effective in the treatment of HCC than the free form of 2,6P-LA in experimental animals.

CONCLUSION

2,6P-LA-bearing escheriosome nanoparticles are effective in suppressing HCC in mice. Original submitted 17 January 2012; Revised submitted 27 August 2012; Published online 14 January 2013.

Lipoidal soft hybrid biocarriers of supramolecular construction for drug delivery

Lipid-based innovations have achieved new heights during the last few years as an essential component of drug development. The current challenge of drug delivery is liberation of drug agents at the right time in a safe and reproducible manner to a specific target site. A number of novel drug delivery systems has emerged encompassing various routes of administration, to achieve controlled and targeted drug delivery. Microparticulate lipoidal vesicular system represents a unique technology platform suitable for the oral and systemic administration of a wide variety of molecules with important therapeutic biological activities, including drugs, genes, and vaccine antigens. The success of liposomes as drug carriers has been reflected in a number of liposome-based formulations, which are commercially available or are currently undergoing clinical trials. Also, novel lipid carrier-mediated vesicular systems are originated. This paper has focused on the lipid-based supramolecular vesicular carriers that are used in various drug delivery and drug targeting systems.

Lipoidal soft hybrid biocarriers of supramolecular construction for drug delivery

Lipid-based innovations have achieved new heights during the last few years as an essential component of drug development. The current challenge of drug delivery is liberation of drug agents at the right time in a safe and reproducible manner to a specific target site. A number of novel drug delivery systems has emerged encompassing various routes of administration, to achieve controlled and targeted drug delivery. Microparticulate lipoidal vesicular system represents a unique technology platform suitable for the oral and systemic administration of a wide variety of molecules with important therapeutic biological activities, including drugs, genes, and vaccine antigens. The success of liposomes as drug carriers has been reflected in a number of liposome-based formulations, which are commercially available or are currently undergoing clinical trials. Also, novel lipid carrier-mediated vesicular systems are originated. This paper has focused on the lipid-based supramolecular vesicular carriers that are used in various drug delivery and drug targeting systems.

Ether lipid vesicle-based antigens impart protection against experimental listeriosis

Background

Incidence of food-borne infections from Listeria monocytogenes, a parasite that has adapted intracellular residence to avoid antibody onslaught, has increased dramatically in the past few years. The apparent lack of an effective vaccine that is capable of evoking the desired cytotoxic T cell response to obliterate this intracellular pathogen has encouraged the investigation of alternate prophylactic strategies. It should also be noted that Archaebacteria (Archae) lipid-based adjuvants enhance the efficacy of subunit vaccines. In the present study, the adjuvant properties of archaeosomes (liposomes prepared from total polar lipids of archaebacteria, Halobacterium salinarum) combined with immunogenic culture supernatant antigens of L. monocytogenes have been exploited in designing a vaccine candidate against experimental listeriosis in murine model.

Methods

Archaeosome-entrapped secretory protein antigens (SAgs) of L. monocytogenes were evaluated for their immunological responses and tendency to deplete bacterial burden in BALB/c mice challenged with sublethal listerial infection. Various immunological studies involving cytokine profiling, lymphocyte proliferation assay, detection of various surface markers (by flowcytometric analysis), and antibody isotypes (by enzyme-linked immunosorbent assay) were used for establishing the vaccine potential of archaeosome-entrapped secretory proteins.

Results

Immunization schedule involving archaeosome-encapsulated SAgs resulted in upregulation of Th1 cytokine production along with boosted memory in BALB/c mice. It also showed protective effect by reducing listerial burden in various vital organs (liver and spleen) of the infected mice. However, the soluble form of the antigens (SAgs) and their physical mixture with sham (empty) archaeosomes, besides showing feeble Th1 response, were unable to protect the animals against virulent listerial infection.

Conclusion

On the basis of the evidence provided by the current data, it is inferred that archaeosome-entrapped SAgs formulation not only enhances cytotoxic T cell response but also helps in the clearance of pathogens and thereby increases the survival of the immunized animals.

Vaccine potential of cytosolic proteins loaded fibrin microspheres of Cryptococcus neoformans in BALB/c mice

Cryptococcosis is a leading mycological cause of mortality among immunologically compromised individuals. In order to develop an effective vaccine against Cryptococcus neoformans, the cytosolic proteins (Cp) of the pathogen have been used as an antigen in combination with different formulations. In the present study, we have demonstrated that Cp encapsulated poly-lactide co-glycolide (PLGA) microsphere further co-encapsulated into the biocompatible fibrin cross-linked plasma beads (Fib-PLGA-Cp) mediated cytosolic delivery elicited strong immune response in the BALB/c mice. In contrast, other formulations of Cp failed to impart significant level of protection. The immune response, involved with Fib-PLGA-Cp protection, appear to interact with the target cells by both endocytosis as well as membrane fusion mode, thus helping in the activation of both CD4(+) and CD8(+) T-cells. Analysis of cytokine profiles in immunized animals revealed that the protective response was associated with the Th1/Th2 polarization in favor of type-1 cytokine [interferons (IFN)-γ and interleukin (IL)-2] cells. Furthermore, vaccination with Fib-PLGA-Cp elicited high immunoglobulin (Ig) G(l) and IgG(2a) isotype response; successfully cleared fungal burden in vital organs and also increased the survival rate of immunized animals. Altogether the present study is a clear indicative of the possible use of fibrin microsphere-based targeted delivery of cytosolic proteins to induce protective immune responses against experimental murine cryptococcosis.

Vaxjo: a web-based vaccine adjuvant database and its application for analysis of vaccine adjuvants and their uses in vaccine development

Vaccine adjuvants are compounds that enhance host immune responses to co-administered antigens in vaccines. Vaxjo is a web-based central database and analysis system that curates, stores, and analyzes vaccine adjuvants and their usages in vaccine development. Basic information of a vaccine adjuvant stored in Vaxjo includes adjuvant name, components, structure, appearance, storage, preparation, function, safety, and vaccines that use this adjuvant. Reliable references are curated and cited. Bioinformatics scripts are developed and used to link vaccine adjuvants to different adjuvanted vaccines stored in the general VIOLIN vaccine database. Presently, 103 vaccine adjuvants have been curated in Vaxjo. Among these adjuvants, 98 have been used in 384 vaccines stored in VIOLIN against over 81 pathogens, cancers, or allergies. All these vaccine adjuvants are categorized and analyzed based on adjuvant types, pathogens used, and vaccine types. As a use case study of vaccine adjuvants in infectious disease vaccines, the adjuvants used in Brucella vaccines are specifically analyzed. A user-friendly web query and visualization interface is developed for interactive vaccine adjuvant search. To support data exchange, the information of vaccine adjuvants is stored in the Vaccine Ontology (VO) in the Web Ontology Language (OWL) format.

Immunization of mice with recombinant protein CobB or AsnC confers protection against Brucella abortus infection

Due to drawbacks of live attenuated vaccines, much more attention has been focused on screening of Brucella protective antigens as subunit vaccine candidates. Brucella is a facultative intracellular bacterium and cell mediated immunity plays essential roles for protection against Brucella infection. Identification of Brucella antigens that present T-cell epitopes to the host could enable development of such vaccines. In this study, 45 proven or putative pathogenesis-associated factors of Brucella were selected according to currently available data. After expressed and purified, 35 proteins were qualified for analysis of their abilities to stimulate T-cell responses in vitro. Then, an in vitro gamma interferon (IFN-γ) assay was used to identify potential T-cell antigens from B. abortus. In total, 7 individual proteins that stimulated strong IFN-γ responses in splenocytes from mice immunized with B. abortus live vaccine S19 were identified. The protective efficiencies of these 7 recombinant proteins were further evaluated. Mice given BAB1_1316 (CobB) or BAB1_1688 (AsnC) plus adjuvant could provide protection against virulent B. abortus infection, similarly with the known protective antigen Cu-Zn SOD and the license vaccine S19. In addition, CobB and AsnC could induce strong antibodies responses in BALB/c mice. Altogether, the present study showed that CobB or AsnC protein could be useful antigen candidates for the development of subunit vaccines against brucellosis with adequate immunogenicity and protection efficacy.

RD antigen based nanovaccine imparts long term protection by inducing memory response against experimental murine tuberculosis

BACKGROUND

The absence of certain genomic loci that are present in most of the virulent strains of Mycobacterium tuberculosis as well as lack of lasting memory responses are some of the major causes attributed to the non effectiveness of Bacille Calmette-Gue'rin (BCG) vaccine. Immunization schedules addressing these issues can offer better strategy for protection against tuberculosis.

METHODS

The immunological responses evoked upon administration of archaeosome based antigen delivery system comprising T cell antigen, Rv3619c (an ESAT-6 family protein), has been assessed against experimental murine tuberculosis in BALB/c mice.

RESULTS

Archaeosome based subunit vaccine has been found to elicit type-1 cytokines in the immunized mice. Besides effective T cell memory response, the Rv3619c based vaccine was able to reduce mycobacterial burden in the animals challenged with Mycobacterium tuberculosis infection.

CONCLUSION

The data of the present study suggest that archaeosome encapsulated RD gene products offer substantial protection against M. tuberculosis infection.

Co-immunization with interlukin-18 enhances the protective efficacy of liposomes encapsulated recombinant Cu-Zn superoxide dismutase protein against Brucella abortus

Brucellosis is a worldwide zoonotic disease caused by Brucella abortus and a number of closely related species. Brucellosis has severe impact on the health and economic prosperity of the developing countries due to the persistent nature of infection and unavailability of effective control measures. The Cu-Zn superoxide dismuatse (SOD) protein of Brucella have been extensively studied as a major antigen involved in bacterial evading mechanism of host defence. Being a critical pro-inflammatory cytokine interleukin-18 (IL-18) plays key role in induction of immune mediated protection against intracellular pathogens. In the present study, we aimed to investigate the immunogenic potential of fusogenic liposomes (escheriosomes) encapsulated recombinant Cu-Zn SOD (rSOD) protein alone or in combination with recombinant IL-18 (rIL-18). Escheriosomes encapsulated rSOD mediated immune responses were further increased upon co-immunization with rIL-18. Furthermore, immunization with escheriosomes encapsulated rSOD alone or in combination with rIL-18, increased resistance in mice against challenge with B. abortus 544.

Molecular characterization of secretory proteins Rv3619c and Rv3620c from Mycobacterium tuberculosis H37Rv

Rv3619c and Rv3620c are the secretory, antigenic proteins of the ESAT-6/CFP-10 family of Mycobacterium tuberculosis H37Rv. In this article, we show that Rv3619c interacts with Rv3620c to form a 1 : 1 heterodimeric complex with a dissociation constant (K(d)) of 4.8 × 10(-7) M. The thermal unfolding of the heterodimer was completely reversible, with a T(m) of 48 °C. The comparative thermodynamics and thermal unfolding analysis of the Rv3619c-Rv3620c dimer, the ESAT-6-CFP-10 dimer and another ESAT family heterodimer, Rv0287-Rv0288, revealed that the binding strength and stability of Rv3619c-Rv3620c are relatively lower than those of the other two pairs. Molecular modeling and docking studies predict the structure of Rv3619c-Rv3620c to be similar to that of ESAT-6-CFP-10. Spectroscopic studies revealed that, in an acidic environment, Rv3619c and Rv3620c lose their secondary structure and interact weakly to form a complex with a lower helical content, indicating that Rv3619c-Rv3620c is destabilized at low pH. These results, combined with those of previous studies, suggest that unfolding of the proteins is required for dissociation of the complex and membrane binding. In the presence of membrane mimetics, the α-helical contents of Rv3619c and Rv3620 increased by 42% and 35%, respectively. In mice, the immune response against Rv3619c protein is characterized by increased levels of interferon-γ, interleukin-12 and IgG(2a) , indicating a dominant Th1 response, which is mandatory for protection against mycobacterial infection. This study therefore emphasizes the potential of Rv3619c as a subunit vaccine candidate.

Towards a Brucella vaccine for humans

There is currently no licensed vaccine for brucellosis in humans. Available animal vaccines may cause disease and are considered unsuitable for use in humans. However, the causative pathogen, Brucella, is among the most common causes of laboratory-acquired infections and is a Center for Disease Control category B select agent. Thus, human vaccines for brucellosis are required. This review highlights the considerations that are needed in the journey to develop a human vaccine, including animal models, and includes an assessment of the current status of novel vaccine candidates.

The profile of cytokines and IgG subclasses in BALB/c mice after immunization with Brucella ribosomal gene

This study was evaluated the ability of DNA vaccine encoding L7/L12 protein of Brucella sp. to induce cellular and humoral immune responses in BALB/c mice and the profile of cytokines and IgG sub classes were determined. Intra muscular vaccination of mice using L7/L12 gene. Three vaccinations at 3 week intervals were performed. Cytokines and IgG subclasses were analyzed 3 week after the last DNA vaccination. Splenic lymphocytes from L7/L12pCDNA3-vaccinated mice produced high levels of IFNy (3100 pg mL(-1)) and low levels of IL-5 (300 pg mL(-1)), 3 weeks post-vaccination. The L7/L12pCDNA3 immunizations elicited high IgG2a isotype response in mice immunized. This antigen also induced IgG1 titers which were slightly lower than the IgG2a titers. Immunological analysis shows the appropriate immune response in BALB/c mice model after vaccination with L7/L12 gene. The high level of IFNgamma and low level of IL-5 in combination with high IgG2a/IgG1 ratio show the activation of Th1 cell response. The lower bacterial cfu from vaccinated mice in comparison with control groups show the efficiency of L7/L12 DNA vaccination in mice model.

Adjuvanticity and protective immunity of Plasmodium yoelii nigeriensis blood-stage soluble antigens encapsulated in fusogenic liposome

In our previous studies we established fusogenic properties of lipids isolated from edible yeast Saccharomyces cerevisiae (S. cerevisiae). We demonstrated that liposomes prepared from S. cerevisiae membrane lipid (saccharosome) can deliver encapsulated antigen into cytosol of the antigen presenting cells and elicit antigen specific cell mediated as well as humoral immune responses. In this study, we evaluated immunological behavior of saccharosome encapsulated cytosolic proteins (sAg) of Plasmodium yoelii nigeriensis in BALB/c mice. Immunization with antigen (sAg) encapsulated in saccharosome resulted in enhancement of CD4+ and CD8+ T cell populations and also up-regulated the expression of CD80 and CD86 molecules on the surface of antigen presenting cells. Further, immunization with saccharosome-encapsulated sAg-induced elevated levels of both IFN-gamma and IL-4 cytokines in the immunized mice when compared to egg PC liposome encapsulated sAg or its IFA emulsified form. Saccharosome-mediated immunization resulted in induction of high level of total antibody response with preponderance of IgG2a isotype as well. The data of this study suggest that saccharosome-based vehicle can emerge as an effective vaccine in imparting protection against various intracellular pathogens including Plasmodium yoelii nigeriensis.