Immunization with a DNA vaccine cocktail induces a Th1 response and protects mice against Mycobacterium avium subsp. paratuberculosis challenge

Proteomic profiling of membrane vesicles from Mycobacterium avium subsp. paratuberculosis: Navigating towards an insilico design of a multi-epitope vaccine targeting membrane vesicle proteins

Bacteria typically produce membrane vesicles (MVs) at varying levels depending on the surrounding environments. Gram-negative bacterial outer membrane vesicles (OMVs) have been extensively studied for over 30 years, but MVs from Gram-positive bacteria only recently have been a focus of research. In the present study, we isolated MVs from Mycobacterium avium subsp. paratuberculosis (MAP) and analyzed their protein composition using LC-MS/MS. A total of 316 overlapping proteins from two independent preparations were identified in our study, and topology prediction showed these cargo proteins have different subcellular localization patterns. When MVs were administered to bovine-derived macrophages, significant up-regulation of pro-inflammatory cytokines was observed via qRT-PCR. Proteome functional annotation revealed that many of these proteins are involved in the cellular protein metabolic process, tRNA aminoacylation, and ATP synthesis. Secretory proteins with high antigenicity and adhesion capability were mapped for B-cell and T-cell epitopes. Antigenic, Immunogenic and IFN-γ inducing B-cell, MHC-I, and MHC-II epitopes were stitched together through linkers to form multi-epitope vaccine (MEV) construct against MAP. Strong binding energy was observed during the docking of the 3D structure of the MEV with the bovine TLR2, suggesting that the putative MEV may be a promising vaccine candidate against MAP. However, in vitro and in vivo analysis is required to prove the immunogenic concept of the MEV which we will follow in our future studies. SIGNIFICANCE: Johne's disease is a chronic infection caused by Mycobacterium avium subsp. paratuberculosis that has a potential link to Crohn's disease in humans. The disease is characterized by persistent diarrhea and enteritis, resulting in significant economic losses due to reduced milk yield and premature culling of infected animals. The dairy industry in the United States alone experiences losses of approximately USD 250 million due to Johne's disease. The current vaccine against Johne's disease is limited by several factors, including variable efficacy, limited duration of protection, interference with diagnostic tests, inability to prevent infection, and logistical and cost-related challenges. Nevertheless, a multiepitope vaccine design approach targeting M. avium subsp. paratuberculosis has the potential to overcome these challenges and offer improved protection against Johne's disease.

Immuno-reactivity evaluation of Mce-truncated subunit candidate vaccine against Mycobacterium avium subspecies paratuberculosis challenge in the goat models

BACKGROUND

Detection of an appropriate antigen with high immunogenicity can be a big step in the production of an effective vaccine for control of Johne's disease (JD). The aim of this study was to evaluate the efficacy of Mce-truncated protein as a subunit vaccine candidate for the control of JD in experimentally challenged goats.

MATERIALS AND METHODS

Six healthy goat kids were immunized with Mce-truncated protein, and two goats were kept as controls. All kids were twice challenged orally with live Mycobacterium avium subspecies paratuberculosis(MAP) strain and half the goats from both the categories were sacrificed at 7 and 10 months after start of challenge study. Culture of MAP was performed from all the necropsied tissues to determine the true JD infection status.

RESULTS

Mce-truncated protein only reacted with pooled vaccinated goat sera in western-blot. A significant increase in humoral immune response against Mce protein was also observed in vaccinated goats. Compared to the control group, vaccinated goats gained higher body weights and none of them shed MAP or showed histopatological lesions or colonization of MAP in their necropsy tissues.

CONCLUSIONS

The new Mce protein based vaccine provided significant immunity in goats as they could meet the challenge with live MAP bacilli. Although the vaccine used in this study showed the high potential as a new effective vaccine for the control of JD, further validation study is still required to successfully implement the vaccine for JD control program.

Alternative Vaccination Routes against Paratuberculosis Modulate Local Immune Response and Interference with Tuberculosis Diagnosis in Laboratory Animal Models

Paratuberculosis (PTB) is an enteric granulomatous disease caused by Mycobacterium avium subsp. paratuberculosis (MAP) that mainly affects ruminants. Current vaccines have shown to be cost–effective control reagents, although they are restricted due to cross-interference with bovine tuberculosis (bTB). Therefore, novel vaccination strategies are needed and this study is focused on evaluating alternative vaccination routes and their effect on the local immune response. The MAP oral challenge rabbit model was used to evaluate and compare an experimental inactivated MAP vaccine through oral (VOR) and intradermal (VID) routes. The VID group presented the highest proportion of animals with no visible lesions and the lowest proportion of animals with MAP positive tissues. Immunohistochemistry analysis revealed that the VID group presented a dominantly M1 polarized response indicating an ability to control MAP infection. In general, all vaccinated groups showed lower calprotectin levels compared to the non-vaccinated challenged group suggesting less active granulomatous lesions. The VID group showed some degree of skin test reactivity, whereas the same vaccine through oral administration was completely negative. These data show that PTB vaccination has an effect on macrophage polarization and that the route influences infection outcome and can also have an impact on bTB diagnosis. Future evaluation of new immunological products against mycobacterial diseases should consider assaying different vaccination routes.

A Novel Approach to Deliver a Mycobacterium avium subsp. paratuberculosis Antigen in Eukaryotic Cells

This study was aimed to express and deliver a Mycobacterium avium subsp. paratuberculosis antigen to macrophages using salmonella as carrier. The coding sequence of a fibronectin attachment protein which is expressed by Mycobacterium avium subsp. paratuberculosis was cloned into pcDNA3.1 (+) plasmid. The construct was introduced into the attenuated Salmonella typhimurium strain SL7207 (ΔhisG, ΔaroA) as carrier. In order to evaluate the delivery capacity of Salmonella and gene expression by antigen-presenting cells, the THP-1 derived macrophages were infected with the salmonella carrier. SDS-PAGE and western blot analysis showed the successful delivery and expression of targeted gene in THP-1 cell line. Although, in vitro stimulation of peripheral blood mononuclear cells with Salmonella containing plasmid did not trigger IFNγ production significantly. But it seems that this carrier can increase plasmid uptake and antigen expression by host intestinal antigen-presenting cells after mucosal administration. So, the construct can be used for further in vivo studies on the Salmonella carrier's efficiency in mycobacterial DNA vaccines.

In vivo electroporation of a codon-optimized BERopt DNA vaccine protects mice from pathogenic Mycobacterium tuberculosis aerosol challenge

DNA vaccines have been extensively studied as preventative and therapeutic interventions for various infectious diseases such as tuberculosis, HIV/AIDS and influenza. Despite promising progresses made, improving the immunogenicity of DNA vaccine remains a technical challenge for clinical development. In this study, we investigated a tuberculosis DNA vaccine BER^opt, which contained a codon-optimized fusion immunogen Ag85B-ESAT-6-Rv2660c for enhanced mammalian cell expression and immunogenicity. BER^opt immunization through in vivo electroporation in BALB/c mice induced surprisingly high frequencies of Ag85B tetramer⁺ CD8⁺ T cells in peripheral blood and IFN-γ-secreting CD8⁺ T cells in splenocytes. Meanwhile, the BER^opt vaccine-induced long-lasting T cell immunity protected BALB/c mice from high dose viral challenge using a modified vaccinia virus Tiantan strain expressing mature Ag85B protein (MVTT-m85B) and the virulent M. tb H37Rv aerosol challenge. Since the BER^opt DNA vaccine does not induce anti-vector immunity, the strong immunogenicity and protective efficacy of this novel DNA vaccine warrant its future development for M. tb prevention and immunotherapy to alleviate the global TB burden.

In silico epitope analysis of unique and membrane associated proteins from Mycobacterium avium subsp. paratuberculosis for immunogenicity and vaccine evaluation

Mycobacterium avium subsp. paratuberculosis (MAP) is the etiologic agent of paratuberculosis disease affecting ruminants worldwide. The aim of this study was to identify potential candidate antigens and epitopes by bio and immuno-informatic tools which could be later evaluated as vaccines and/or diagnosis. 110 protein sequences were selected from MAP K-10 genome database: 48 classified as putative enzymes involved in surface polysaccharide and lipopolysaccharide synthesis, as membrane associated and secreted proteins, 32 as conserved membrane proteins, and 30 as absent from other mycobacterial genomes. These 110 proteins were preliminary screened for Major Histocompatibility Complex (MHC) class II affinity and promiscuity using ProPred program. In addition, subcellular localization and host protein homology was analyzed. From these analyses, 23 MAP proteins were selected for a more accurate inmunoinformatic analysis (i.e. T cell and B cell epitopes analysis) and for homology with mycobacterial proteins. Finally, eleven MAP proteins were identified as potential candidates for further immunogenic evaluation: six proteins (MAP0228c, MAP1239c, MAP2232, MAP3080, MAP3131 and MAP3890) were identified as presenting potential T cell epitopes, while 5 selected proteins (MAP0232c, MAP1240c, MAP1738, MAP2239 and MAP3641c) harbored a large numbers of epitopes predicted to induce both cell- and antibody-mediated immune responses. Moreover, immunogenicity of selected epitopes from MAP1239c were evaluated in IFN-γ release assay. In summary, eleven M. avium subsp. paratuberculosis proteins were identified by in silico analysis and need to be further evaluated for their immunodiagnostic and vaccine potential in field and mice model.

A rational framework for evaluating the next generation of vaccines against Mycobacterium avium subspecies paratuberculosis

Since the early 1980s, several investigations have focused on developing a vaccine against Mycobacterium avium subspecies paratuberculosis (MAP), the causative agent of Johne's disease in cattle and sheep. These studies used whole-cell inactivated vaccines that have proven useful in limiting disease progression, but have not prevented infection. In contrast, modified live vaccines that invoke a Th1 type immune response, may improve protection against infection. Spurred by recent advances in the ability to create defined knockouts in MAP, several independent laboratories have developed modified live vaccine candidates by transpositional mutation of virulence and metabolic genes in MAP. In order to accelerate the process of identification and comparative evaluation of the most promising modified live MAP vaccine candidates, members of a multi-institutional USDA-funded research consortium, the Johne's disease integrated program (JDIP), met to establish a standardized testing platform using agreed upon protocols. A total of 22 candidates vaccine strains developed in five independent laboratories in the United States and New Zealand voluntarily entered into a double blind stage gated trial pipeline. In Phase I, the survival characteristics of each candidate were determined in bovine macrophages. Attenuated strains moved to Phase II, where tissue colonization of C57/BL6 mice were evaluated in a challenge model. In Phase III, five promising candidates from Phase I and II were evaluated for their ability to reduce fecal shedding, tissue colonization and pathology in a baby goat challenge model. Formation of a multi-institutional consortium for vaccine strain evaluation has revealed insights for the implementation of vaccine trials for Johne's disease and other animal pathogens. We conclude by suggesting the best way forward based on this 3-phase trial experience and challenge the rationale for use of a macrophage-to-mouse-to native host pipeline for MAP vaccine development.

Immune responses elicited by Mycoplasma hyopneumoniae recombinant antigens and DNA constructs with potential for use in vaccination against porcine enzootic pneumonia

Mycoplasma hyopneumoniae is the etiological agent of porcine enzootic pneumonia (PEP) and causes major economic losses to the pig industry worldwide. Commercially available vaccines provide only partial protection and are relatively expensive. In this study, we assessed the humoral and cellular immune responses to three recombinant antigens of M. hyopneumoniae. Immune responses to selected domains of the P46, HSP70 and MnuA antigens (P46102-253, HSP70212-601 and MnuA182-378), delivered as recombinant subunit or DNA vaccines, were evaluated in BALB/c mice. All purified recombinant antigens and two DNA vaccines, pcDNA3.1(+)/HSP70212-601 and pcDNA3.1(+)/MnuA182-378, elicited a strong humoral immune response, indicated by high IgG levels in the serum. The cellular immune response was assessed by detection of IFN-γ, IL-10 and IL-4 in splenocyte culture supernatants. The recombinant subunit and DNA vaccines induced Th1-polarized immune responses, as evidenced by increased levels of IFN-γ. All recombinant subunit vaccines and the pcDNA3.1(+)/MnuA182-378 vaccine also induced the secretion of IL-10, a Th2-type cytokine, in large quantities. The mixed Th1/Th2-type response may elicit an effective immune response against M. hyopneumoniae, suggesting that P46102-253, HSP70212-601 and MnuA182-378 are potential novel and promising targets for the development of vaccines against PEP.

Cellular and humoral immune responses in sheep vaccinated with candidate antigens MAP2698c and MAP3567 from Mycobacterium avium subspecies paratuberculosis

Control of Johne's disease, caused by Mycobacterium avium subspecies paratuberculosis (MAP) in ruminants using commercially available vaccine reduces production losses, mortality, fecal shedding and histopathological lesions but does not provide complete protection from infection and interferes with serological diagnosis of Johne's disease and bovine tuberculosis. At this time no recombinant antigens have been found to provide superior protection compared to whole killed or live-attenuated MAP vaccines. Therefore, there is a need to evaluate more candidate MAP antigens. In this study recombinant MAP antigens MAP2698c and MAP3567 were formulated with four different MONTANIDE™ (ISA 50V2, 61VG, 71VG, and 201VG) adjuvants and evaluated for their ability to produce specific immune responses in vaccinated sheep. The cellular immune response was measured with an interferon-gamma (IFN-γ) release assay and the humoral immune response was measured by antibody detection enzyme linked immunosorbent assay. Recombinant vaccine formulation with the antigen MAP2698c and MONTANIDE™ ISA 201VG adjuvant produced strong whole-MAP as well as MAP2698c-specific IFN-γ responses in a high proportion of the vaccinated sheep. The formulation caused less severe injection site lesions in comparison to other formulations. The findings from this study suggest that the MAP2698c + 201VG should be evaluated in a challenge trial to determine the efficacy of this vaccine candidate.

Evaluation of a Salmonella vectored vaccine expressing Mycobacterium avium subsp. paratuberculosis antigens against challenge in a goat model

Johnes disease (JD), caused by Mycobacterium avium subsp paratuberculosis (MAP), occurs worldwide as chronic granulomatous enteritis of domestic and wild ruminants. To develop a cost effective vaccine, in a previous study we constructed an attenuated Salmonella strain that expressed a fusion product made up of partial fragments of MAP antigens (Ag85A, Ag85B and SOD) that imparted protection against challenge in a mouse model. In the current study we evaluated the differential immune response and protective efficacy of the Sal-Ag vaccine against challenge in a goat model as compared to the live attenuated vaccine MAP316F. PBMCs from goats vaccinated with Sal-Ag and challenged with MAP generated significantly lower levels of IFN-γ, following in vitro stimulation with either Antigen-mix or PPD jhonin, than PBMC from MAP316F vaccinated animals. Flow cytometric analysis showed the increase in IFN-γ correlated with a significantly higher level of proliferation of CD4, CD8 and γδT cells and an increased expression of CD25 and CD45R0 in MAP316F vaccinated animals as compared to control animals. Evaluation of a range of cytokines involved in Th1, Th2, Treg, and Th17 immune responses by quantitative PCR showed low levels of expression of Th1 (IFN-γ, IL-2, IL-12) and proinflammatory cytokines (IL-6, IL-8, IL-18, TNF-α) in the Sal-Ag immunized group. Significant levels of Th2 and anti-inflammatory cytokines transcripts (IL-4, IL-10, IL-13, TGF-β) were expressed but their level was low and with a pattern similar to the control group. Over all, Sal-Ag vaccine imparted partial protection that limited colonization in tissues of some animals upon challenge with wild type MAP but not to the level achieved with MAP316F. In conclusion, the data indicates that Sal-Ag vaccine induced only a low level of protective immunity that failed to limit the colonization of MAP in infected animals. Hence the Sal-Ag vaccine needs further refinement to increase its efficacy.

Codon optimisation to improve expression of a Mycobacterium avium ssp. paratuberculosis-specific membrane-associated antigen by Lactobacillus salivarius

Subunit and DNA-based vaccines against Mycobacterium avium ssp. paratuberculosis (MAP) attempt to overcome inherent issues associated with whole-cell formulations. However, these vaccines can be hampered by poor expression of recombinant antigens from a number of disparate hosts. The high G+C content of MAP invariably leads to a codon bias throughout gene expression. To investigate if the codon bias affects recombinant MAP antigen expression, the open reading frame of a MAP-specific antigen MptD (MAP3733c) was codon optimised for expression against a Lactobacillus salivarius host. Of the total 209 codons which constitute MAP3733c, 172 were modified resulting in a reduced G+C content from 61% for the native gene to 32.7% for the modified form. Both genes were placed under the transcriptional control of the PnisA promoter; allowing controlled heterologous expression in L. salivarius. Expression was monitored using fluorescence microscopy and microplate fluorometry via GFP tags translationally fused to the C-termini of the two MptD genes. A > 37-fold increase in expression was observed for the codon-optimised MAP3733synth variant over the native gene. Due to the low cost and improved expression achieved, codon optimisation significantly improves the potential of L. salivarius as an oral vaccine stratagem against Johne's disease.

Evaluation of a Mycobacterium avium subsp. paratuberculosis leuD mutant as a vaccine candidate against challenge in a caprine model

Johne's disease (JD) is prevalent worldwide and has a significant impact on the global agricultural economy. In the present study, we evaluated the protective efficacy of a leuD (Δleud) mutant and gained insight into differential immune responses after challenge with virulent M. avium subsp. paratuberculosis in a caprine colonization model. The immune response and protective efficacy were compared with those of the killed vaccine Mycopar. In vitro stimulation of peripheral blood mononuclear cells with johnin purified protein derivative showed that Mycopar and ΔleuD generated similar levels of gamma interferon (IFN-γ) but significantly higher levels than unvaccinated and challenged phosphate-buffered saline controls. However, only with ΔleuD was the IFN-γ response maintained. Flow cytometric analysis showed that the increase in IFN-γ correlated with proliferation and activation (increased expression of CD25) of CD4, CD8, and γδT cells, but this response was significantly higher in ΔleuD-vaccinated animals at some time points after challenge. Both Mycopar and ΔleuD vaccines upregulated Th1/proinflammatory and Th17 cytokines and downregulated Th2/anti-inflammatory and regulatory cytokines at similar levels at almost all time points. However, significantly higher levels of IFN-γ (at weeks 26 and 30), interleukin-2 (IL-2; week 18), IL-1b (weeks 14 and 22), IL-17 (weeks 18 and 22), and IL-23 (week 18) and a significantly lower level of IL-10 (weeks 14 and 18) and transforming growth factor β (week 18) were detected in the ΔleuD-vaccinated group. Most importantly, ΔleuD elicited an immune response that significantly limited colonization of tissues compared to Mycopar upon challenge with wild-type M. avium subsp. paratuberculosis. In conclusion, the ΔleuD mutant is a promising vaccine candidate for development of a live attenuated vaccine for JD in ruminants.

Cell-mediated and humoral immune responses after immunization of calves with a recombinant multiantigenic Mycobacterium avium subsp. paratuberculosis subunit vaccine at different ages

Neonates and juvenile ruminants are very susceptible to paratuberculosis infection. This is likely due to a high degree of exposure from their dams and an immature immune system. To test the influence of age on vaccine-induced responses, a cocktail of recombinant Mycobacterium avium subsp. paratuberculosis proteins (MAP0217, MAP1508, MAP3701c, MAP3783, and MAP1609c/Ag85B) was formulated in a cationic liposome adjuvant (CAF01) and used to vaccinate animals of different ages. Male jersey calves were divided into three groups that were vaccinated at 2, 8, or 16 weeks of age and boosted twice at weeks 4 and 12 relative to the first vaccination. Vaccine-induced immune responses, the gamma interferon (IFN-γ) cytokine secretion and antibody responses, were followed for 20 weeks. In general, the specific responses were significantly elevated in all three vaccination groups after the first booster vaccination with no or only a minor effect from the second booster. However, significant differences were observed in the immunogenicity levels of the different proteins, and it appears that the older age group produced a more consistent IFN-γ response. In contrast, the humoral immune response is seemingly independent of vaccination age as we found no difference in the IgG1 responses when we compared the three vaccination groups. Combined, our results suggest that an appropriate age of vaccination should be considered in vaccination protocols and that there is a possible interference of vaccine-induced immune responses with weaning (week 8).

Immune response and protective efficacy of live attenuated Salmonella vaccine expressing antigens of Mycobacterium avium subsp. paratuberculosis against challenge in mice

Mycobacterium avium subsp. paratuberculosis (MAP) causes chronic granulomatous enteritis in ruminants that leads to diarrhea and eventually death. Existing vaccines have proven useful in limiting disease progression but have not been effective in preventing infection. To address this problem we constructed an attenuated Salmonella (ΔyejE; ΔssaV) strain harboring a plasmid that expressed a fusion protein comprised of the Salmonella Type III secretion system (T3SS) effector SopE and MAP antigens (85A, 85B, SOD, 74F) and evaluated its potential as vaccine candidate against MAP infection in mice. Of various SopE-MAP fusion proteins analyzed, only SopE104-Ag85A C-terminal(202-347)-SOD N-terminal(1-72)-Ag85B C-terminal(173-330) and SopE104-74F(1-148+669-786)were successfully expressed and secreted into culture media as revealed by western blot analysis. Mice immunized with attenuated Salmonella (ΔyejE; ΔssaV) harboring the SopE104-Ag85A C-terminal(202-347)-SOD N-terminal(1-72)-Ag85B C-terminal(173-330) and SopE104-74F(1-148+669-786)plasmid generated a potent and long lasting Th1 response characterized by production of IFN-γ. The cytokine profile varied at various time points after immunization and challenge, which showed down regulation of Th2 cytokines (IL-4, IL-10) and up-regulation of proinflammatory cytokines (IL-12 and IL-17). Further, the immune response correlated with protection as revealed by reduced bacterial load and improved histopathology of spleen and liver, which showed fewer granulomas and lower numbers of acid-fast bacilli as compared to PBS controls. Interestingly, vaccination with antigens mixed with Ribi adjuvant (Agmix+Ribi) imparted better protection than the attenuated salmonella vectored vaccine. Thus, priming with a live recombinant Salmonella strain that secretes MAP antigens represents a promising approach that could lead to development of an efficacious and cost effective vaccine for Johne's disease.

Phenotypic and transcriptomic response of auxotrophic Mycobacterium avium subsp. paratuberculosis leuD mutant under environmental stress

Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of severe gastroenteritis in cattle. To gain a better understanding of MAP virulence, we investigated the role of leuD gene in MAP metabolism and stress response. For this, we have constructed an auxotrophic strain of MAP by deleting the leuD gene using allelic exchange. The wildtype and mutant strains were then compared for metabolic phenotypic changes using Biolog phenotype microarrays. The responses of both strains to physiologically relevant stress conditions were assessed using DNA microarrays. Transcriptomic data was then analyzed in the context of cellular metabolic pathways and gene networks. Our results showed that deletion of leuD gene has a global effect on both MAP phenotypic and transcriptome response. At the metabolic level, the mutant strain lost the ability to utilize most of the carbon, nitrogen, sulphur, phosphorus and nutrient supplements as energy source. At the transcriptome level, more than 100 genes were differentially expressed in each of the stress condition tested. Systems level network analysis revealed that the differentially expressed genes were distributed throughout the gene network, thus explaining the global impact of leuD deletion in metabolic phenotype. Further, we find that leuD deletion impacted metabolic pathways associated with fatty acids. We verified this by experimentally estimating the total fatty acid content of both mutant and wildtype. The mutant strain had 30% less fatty acid content when compared to wildtype, thus supporting the results from transcriptional and computational analyses. Our results therefore reveal the intricate connection between the metabolism and virulence in MAP.

Leishmania donovani recombinant iron superoxide dismutase B1 protein in the presence of TLR-based adjuvants induces partial protection of BALB/c mice against Leishmania major infection

In this study, we tested the protective efficacy of recombinant Leishmania donovani iron superoxide dismutase B1 (SODB1) against Leishmania major infection in BALB/c mice. Mice were challenged with L. major 3weeks after the second boost immunization with rSODB1 alone or in the presence of adjuvants. Injection of BALB/c mice with rSODB1 alone elicited both humoral and cellular immune responses. Administration of rSODB1 with CpG ODN or GLA-SE (a synthetic toll-like receptor 4 agonist) adjuvant resulted in the induction of anti-SODB1 IgG1, and more importantly of significantly high levels of IgG2a isotype. Immunization of mice with rSODB1 alone or with adjuvant induced the production of IFN-γ by splenocytes in response to stimulation with L. major soluble leishmanial antigens (SLA). Moreover, immunization protocols involving rSODB1 resulted in a significant decrease in IL-10 as compared to controls. The presence of CpG ODN or GLA-SE adjuvant in the immunization protocols resulted in a relative increase in IFN-γ in response to stimulation with rSODB1 in comparison to immunization with rSODB1 alone. Mice immunized with rSODB1 plus CpG ODN or GLA-SE, were able to partially control their Leishmania infections, as indicated by the reduction in footpad swelling and parasite numbers, compared to controls. These results suggest that immunization with recombinant SODB1 protein together with CpG ODN or GLA-SE can be potential vaccine candidate against leishmaniasis.

Immunogenicity and protective efficacy of the Mycobacterium avium subsp. paratuberculosis attenuated mutants against challenge in a mouse model

Johne's disease (JD), caused by Mycobacterium avium subsp. paratuberculosis (MAP), results in serious economic losses worldwide especially in cattle, sheep and goats. To control the impact of JD on the animal industry, an effective vaccine with minimal adverse effects is urgently required. In order to develop an effective vaccine, we used allelic exchange to construct three mutant MAP strains, leuD, mpt64 and secA2. The mutants were attenuated in a murine model and induced cytokine responses in J774A.1 cell. The leuD mutant was the most obviously attenuated of the three constructed mutant strains. Our preliminary vaccine trial in mice demonstrated different levels of protection were induced by these mutants based on the acid-fast bacilli burden in livers and spleens at 8 and 12 weeks postchallenge. In addition, vaccination with leuD mutant induced a high level of IFN-γ production and significant protective efficacy in both the reduction of inflammation and clearance of acid-fast bacilli, as compared with the mock vaccinated group.

Paratuberculosis control: a review with a focus on vaccination

Mycobacterium avium subsp. paratuberculosis (MAP) infection causes in ruminants a regional chronic enteritis that is increasingly being recognized as a significant problem affecting animal health, farming and the food industry due to the high prevalence of the disease and to recent research data strengthening the link between the pathogen and human inflammatory bowel disease (IBD). Control of the infection through hygiene-management measures and test and culling of positive animals has to date not produced the expected results and thus a new focus on vaccination against this pathogen is necessary. This review summarizes all vaccination studies of cattle, sheep or goats reporting production, epidemiological or pathogenetic effects of vaccination published before January 2010 and that provide data amenable to statistical analyses. The meta analysis run on the selected data, allowed us to conclude that most studies included in this review reported that vaccination against MAP is a valuable tool in reducing microbial contamination risks of this pathogen and reducing or delaying production losses and pathogenetic effects but also that it did not fully prevent infection. However, the majority of MAP vaccines were very similar and rudimentary and thus there is room for improvement in vaccine types and formulations.

Immunogenicity of Leishmania donovani iron superoxide dismutase B1 and peroxidoxin 4 in BALB/c mice: the contribution of Toll-like receptor agonists as adjuvant

In this study, we assessed the immune response of two Leishmania donovani recombinant proteins: iron superoxide dismutase B1 (SODB1) and peroxidoxin 4 (Pxn4) in BALB/c mice. Assessment of the immunogenicity of these proteins alone or combined with Toll-like receptor 9 (TLR-9) agonist (CpG ODN) or TLR-4 agonist (GLA-SE) showed that they elicit specific antibody as well as cytokine production in response to the respective antigen in vitro. The use of adjuvants augmented immunogenicity of these antigens and more importantly, skewed the immune response to a Th1-type. These results indicate that recombinant SODB1 and Pxn4 proteins are potential vaccine candidates when administered with appropriate adjuvants.

Novel antigens for detection of cell mediated immune responses to Mycobacterium avium subsp. paratuberculosis infection in cattle

Paratuberculosis is a chronic infection of the intestine of ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). Early stage MAP infection can be detected by measuring specific cell mediated immune responses, using the whole blood interferon-γ (IFN-γ) assay. Available IFN-γ assays use purified protein derivative of MAP (PPDj) which are complex antigen mixtures with low specificity. The objectives of this study were to evaluate immunogenicity and specificity of 14 novel recombinant antigens for use in the IFN-γ assay and to assess the consistency of IFN-γ responses. The study included blood samples from 26 heifers from a MAP infected herd, collected three times with four to five-week intervals, and blood samples from 60 heifers of a non-infected herd collected once. Heifers of the non-infected herd were used to establish cut-off values for each antigen. The case definition was an animal with ≥ 2 positive tests for ≥ 4 antigens, resulting in 13 cases and 13 non-cases. IFN-γ levels of cases were higher compared to IFN-γ levels of non-cases (P<0.05). The results of the IFN-γ assay using PPDj did not correlate well with the results using the novel antigens. PPDj produced elevated IFN-γ responses of samples from both the non-infected and the MAP infected herd, indicating unspecific IFN-γ responses and showed low consistency. Three latency proteins, LATP-1, LATP-2 and LATP-3 gave positive IFN-γ tests that correlated very well with the case definition suggesting high immunogenicity. Three tested antigens, LATP-2, MAP-1 and MAP-2 have no homologue in the M. avium subsp. avium or M. bovis genome and could be promising diagnostic antigens, especially LATP-2 correlated highly with the case definition.