Induction of protective cellular immune responses against experimental visceral leishmaniasis mediated by dendritic cells pulsed with the N-terminal domain of Leishmania infantum elongation factor-2 and CpG oligodeoxynucleotides

Protective Efficacy Induced by the Common Eimeria Antigen Elongation Factor 2 against Challenge with Three Eimeria Species in Chickens

Avian coccidiosis arises from co-infection involving multiple Eimeria species, which could give rise to substantial economic losses in the global poultry industry. As a result, multivalent anticoccidial vaccines containing common Eimeria antigens offer considerable promise for controlling co-infection in clinical practice. In our previous study, Elongation factor 2 (EF2) was deemed as an immunogenic common antigen across various Eimeria species. This current investigation aimed to further assess the immunogenicity and protective efficacy of EF2 in recombinant subunit vaccine format against three Eimeria species. The EF2 gene cloned from Eimeria maxima (E. maxima) cDNA was designated as EF2 of E. maxima (EmEF2). The immunogenicity of the recombinant protein EmEF2 (rEmEF2) was assessed through Western blot analysis. The evaluation of the vaccine-induced immune response encompassed the determination of T lymphocyte subset proportions, cytokine mRNA transcription levels, and specific IgY concentrations in rEmEF2-vaccinated chickens using flow cytometry, quantitative real-time PCR (qPCR), and indirect enzyme-linked immunosorbent assay (ELISA). Subsequently, the protective efficacy of rEmEF2 was evaluated through vaccination and challenge experiments. The findings demonstrated that rEmEF2 was effectively recognized by the His-tag monoclonal antibody and E. maxima chicken antiserum. Vaccination with rEmEF2 increased the proportions of CD4+ and CD8+ T lymphocytes, elevated IL-4 and IFN-γ mRNA transcription levels, and enhanced IgY antibody levels compared to the control groups. Moreover, compared to the control groups, vaccination with rEmEF2 led to decreased weight loss, reduced oocyst outputs, and alleviated enteric lesions. Furthermore, in the rEmEF2-immunized groups, challenges with E. maxima and E. acervulina resulted in anticoccidial index (ACI) scores of 166.35 and 185.08, showing moderate-to-excellent protective efficacy. Nevertheless, challenges with E. tenella and mixed Eimeria resulted in ACI scores of 144.01 and 127.94, showing low protective efficacy. In conclusion, EmEF2, a common antigen across Eimeria species, demonstrated the capacity to induce a significant cellular and humoral immune response, as well as partial protection against E. maxima, E. acervulina, and E. tenella. These results highlight EmEF2 as a promising candidate antigen for the development of multivalent vaccines targeting mixed infections by Eimeria species.

TLR9 agonist CpG ODN 2395 promotes the immune response against Leishmania donovani in obesity and undernutrition mice

As important immunomodulators, CpG ODNs have broad application prospects in the treatment and prevention of leishmaniasis. In order to explore the immunomodulatory effect of CpG ODNs on mice infected with Leishmania parasites in different nutritional status, TLR9 agonist CpG ODN 2395 or TLR9 antagonist CpG ODN 2088 was injected into normal, obesity and undernutrition BALB/c mice infected with Leishmania donovani, respectively. Subsequently, spleen and liver parasite loads, spleen and liver immune gene expression, spleen T cell subsets proportion and PD-1 expression, serum lipids, serum cytokines, and anti-Leishmania antibodies were measured to assess the immune response of mice with different nutritional status. The results displayed that at the 8th week after infection, the spleen parasite load of obesity and undernutrition mice was significantly higher than that of normal mice, but the liver parasite load showed no statistical difference among the three groups. The treatment of CpG ODN 2395 or CpG ODN 2088 significantly reduced the spleen parasite load of obesity and undernutrition infected mice, but did not reduce that of normal infected mice. In obesity infected mice, CpG ODN 2395 promoted the up-regulation of TCR, ICOS and TLR4 in spleen, promoted the secretion of IFN-γ and anti-Leishmania total IgG and IgG1 antibodies, and increased the content of serum HDL-C. In undernutrition infected mice, CpG ODN 2395 promoted the up-regulation of spleen CD28 and TLR9, increased the proportion of spleen CD3⁺ T cells, and decreased the content of serum IL-10. Our results demonstrated that CpG ODN 2395 enhanced the immune response and clearance of Leishmania parasites in obesity and undernutrition mice, which might be used as a therapeutic agent for obesity and undernutrition leishmaniasis patients in the future.

Combined immunotherapeutic effect of Leishmania-derived recombinant aldolase and Ambisome against experimental visceral leishmaniasis

BACKGROUND

Available therapeutics for visceral leishmaniasis (VL), a deadly parasitic infection, are usually associated with inadequate efficacy and adverse aftereffects. Further, the primary site of Leishmania parasite are host macrophages resulting in compromised immunity; ensuing marked T-cell immunosuppression. Such settings emphasize the exploration of chemo-immunotherapeutic strategies for improvising the infected person's immune status with better resolution of infection.

METHODS

Present work employs the immunization of Leishmania-infected hamsters with Leishmania-derived recombinant aldolase (rLdAld) and enolase (rLdEno) proteins in consort with the sub-optimal dose of Ambisome (2.5 mg/kg). After the completion of immunization, hamsters were sacrificed on day 60 and 90 post infection and different organ samples were collected to perform immunological assay for evaluating the therapeutic efficacy and modulation in protective cellular immune responses.

RESULTS

Combining these proteins, particularly rLdAld with Ambisome (2.5 mg/kg), has significantly reduced the parasitic load (∼80%) with remarkable enhancement in DTH and lymphoproliferative responses compared to the infected control and only Ambisome treated groups. Moreover, cytokine levels at RNA and protein levels were noticed to be inclined towards Th-1 phenotype through up-regulation of IFN-γ and TNF-α with significant down-regulation in IL-10 and TGF-β expression, an indication towards the generation of protective immunity against experimental VL.

CONCLUSION

Our experimental findings demonstrated that the chemo-immunotherapeutic approach could be an effective way of controlling human VL infection at minimal dosages of antileishmanial with reduced side-effects and propensity of drug resistance emergence.

An insight into differential protein abundance throughout Leishmania donovani promastigote growth and differentiation

Leishmania donovani causes anthroponotic visceral leishmaniasis, responsible for about 50,000 annual deaths worldwide. Current therapies have considerable side effects. Drug resistance has been reported and no vaccine is available nowadays. The development of undifferentiated promastigotes in the sand fly vector's gut leads to the promastigote form that is highly infective to the mammalian host. Fully differentiated promastigotes play a crucial role in the initial stages of mammalian host infection before internalization in the host phagocytic cell. Therefore, the study of protein levels in the promastigote stage is relevant for disease control, and proteomics analysis is an ideal source of vaccine candidate discovery. This study aims to get insight into the protein levels during the differentiation process of promastigotes by 2DE-MALDI-TOF/TOF. This partial proteome analysis has led to the identification of 75 proteins increased in at least one of the L. donovani promastigote differentiation and growth phases. This study has revealed the differential abundance of said proteins during growth and differentiation. According to previous studies, some are directly involved in parasite survival or are immunostimulatory. The parasite survival-related proteins are ascorbate peroxidase; cystathionine β synthase; an elongation factor 1β paralog; elongation factor 2; endoribonuclease L-PSP; an iron superoxide dismutase paralog; GDP-mannose pyrophosphorylase; several heat shock proteins-HSP70, HSP83-17, mHSP70-rel, HSP110; methylthioadenosine phosphorylase; two thiol-dependent reductase 1 paralogs; transitional endoplasmic reticulum ATPase; and the AhpC thioredoxin paralog. The confirmed immunostimulatory proteins are the heat shock proteins, enolase, and protein kinase C receptor analog. The potential immunostimulatory molecules according to findings in patogenic bacteria are fructose-1,6-diphophate aldolase, dihydrolipoamide acetyltransferase, isocitrate dehydrogenase, pyruvate dehydrogenase E1α and E1β subunits, and triosephosphate isomerase. These proteins may become disease control candidates through future intra-vector control methods or vaccines.

Determinants of Innate Immunity in Visceral Leishmaniasis and Their Implication in Vaccine Development

Leishmaniasis is endemic to the tropical and subtropical regions of the world and is transmitted by the bite of an infected sand fly. The multifaceted interactions between Leishmania, the host innate immune cells, and the adaptive immunity determine the severity of pathogenesis and disease development. Leishmania parasites establish a chronic infection by subversion and attenuation of the microbicidal functions of phagocytic innate immune cells such as neutrophils, macrophages and dendritic cells (DCs). Other innate cells such as inflammatory monocytes, mast cells and NK cells, also contribute to resistance and/or susceptibility to Leishmania infection. In addition to the cytokine/chemokine signals from the innate immune cells, recent studies identified the subtle shifts in the metabolic pathways of the innate cells that activate distinct immune signal cascades. The nexus between metabolic pathways, epigenetic reprogramming and the immune signaling cascades that drive the divergent innate immune responses, remains to be fully understood in Leishmania pathogenesis. Further, development of safe and efficacious vaccines against Leishmaniasis requires a broader understanding of the early interactions between the parasites and innate immune cells. In this review we focus on the current understanding of the specific role of innate immune cells, the metabolomic and epigenetic reprogramming and immune regulation that occurs during visceral leishmaniasis, and the strategies used by the parasite to evade and modulate host immunity. We highlight how such pathways could be exploited in the development of safe and efficacious Leishmania vaccines.

Genome mutations of the Turkish strain Leishmania infantum_TR01

PURPOSE

Today, almost 15 years have passed since the whole genome sequence (WGS) of a Leishmania parasite was completed for the first time. However, information on the genetics of these parasites remains to be elucidated. Genome-based studies may contribute to control strategies for leishmaniasis. The increase in genetically based studies, particularly whole-genome sequencing studies on Leishmania, will contribute to the control of leishmaniasis, which is a common and neglected disease worldwide. Our previous study obtained the Leishmania infantum_TR01 (Lin_TR01) genome sequence (Guldemir et al., 2020). In the present study, we focused on the mutations detected in the genome and aimed to investigate the effects of these mutations.

METHODS

In our previous study, the whole-genome sequence of the L. infantum_TR01 strain was obtained (Guldemir et al., 2020). In the present study, 3153 polymorphisms were detected in bioinformatics analysis performed on the Geneious 11.0.5. (www.geneious.com) platform. Herein, the L. infantum JPCM5 strain was used as the reference genome for genome mapping. Polymorphic regions were determined using the Find Variations/SNPs program on the Geneious platform. We further analyzed these polymorphisms detected in the previous study. Additionally, a literature review was performed by searching the PubMed database for proteins with polymorphisms.

RESULTS

In our previous study (Guldemir et al., 2020), the genomic DNA sequence was submitted to the NCBI GenBank (www.ncbi.nlm.nih.gov) database and registered under the name Leishmania infantum_TR01 (Lin_TR01) and project accession number PRJNA437593. As a result of the annotation of the genome, 3153 polymorphisms were identified. In this study, 166 protein-coding polymorphisms were found among the 3153 polymorphisms, affecting 63 different proteins. Fourteen of them were studied, and the remaining 49 proteins were not studied. The 14 proteins examined in terms of the mutations detected in this study were related to virulence (n = 5), vaccine candidates (n = 2), diagnosis/typing (n = 4), drug resistance (n = 2), drug targets (n = 3) and vital function (n = 1).

CONCLUSION

As mentioned previously, the acquisition of the Lin_TR01 genome was described in our previous study (Guldemir et al., 2020). The present meta-analytical study is the first comparison report of whole-genome sequence-based polymorphisms between the Turkish strain Leishmania infantum_TR01 and reference Leishmania infantum JPCM5 strain and evaluated polymorphisms and proteins. In this study, we focused on the mutations detected in the genome, and the effects of these mutations were investigated and evaluated together with the current literature. In our previous study, a high-quality WGS of Leishmania infantum was successfully obtained for the first time in Turkey (1). In this study, the comparison of both genomes will contribute to providing the scientific community with a solid infrastructure for postgenomic investigations of the parasite.

Immunoproteomic analysis of fish ectoparasite, Argulus siamensis antigens

AIM

An immunoproteomic approach was followed to identify immunoreactive antigens of fish ectoparasite, Argulus siamensis with rohu (Labeo rohita) immune sera for screening of potential vaccine candidates.

MATERIALS AND RESULTS

The whole adult Argulus antigen was run in 2D electrophoresis with IEF in 7 cm IPG strips of pH 4-7 and SDS-PAGE with 12% acrylamide concentration. Two parallel gels were run; one was stained with silver stain, and the other was Western blotted to nitrocellulose paper (NCP) and reacted with rohu anti-A siamensis sera. Fourteen protein spots corresponding to the spots developed in NCP were picked from the silver-stained gel and subjected to mass spectrometry in MALDI-TOF/TOF. The MS/MS spectra were analysed in MASCOT software with taxonomy 'other metazoa' and the proteins identified based on similarity with the proteins from heterologous species. The gene ontology analysis revealed a majority of proteins being involved in binding activity in 'molecular function' and belonging to metabolic processes in 'biologic process' categories. The possibility of these proteins as vaccine candidates against A siamensis is discussed in the paper.

CONCLUSION

Three of the identified proteins namely, bromodomain-containing protein, anaphase-promoting complex subunit 5 and elongation factor-2 could possibly serve as vaccine candidates against argulosis in carps.

The immunity of the recombinant prokaryotic and eukaryotic subunit vaccines against cutaneous leishmaniasis

Leishmaniasis counts as one of the most neglected tropical diseases. Despite the amount of research perceived in this field, no fully effective and approved vaccine against this disease is yet available in humans. In this study, LACK and KMP11 antigens were constructed simultaneously by recombinant methods in prokaryotic and eukaryotic expression systems and were compared and assessed along with the CpG adjuvant in BALB/c mice. In the prokaryotic method, LACK and KMP11 protein gene sequences were synthesized in pET28a-TEV vector. In order to extract these two proteins after expression, His-tag and S-tag sequences were added to the constructs, respectively for LACK and KMP11. The pET28a-TEV-LACK/KMP11 construct was transformed into Escherichia coli, and the inserts were verified by Colony PCR. Pure proteins were verified by western blot, and groups of BALB/c mice were injected with the created prokaryotic recombinant proteins along with an ODN CpG adjuvant. In the eukaryotic method, antigen sequences were constructed in the pLEXSY-neo 2.1 vector, E.coli Top10 strain was cloned in the bacteria, and after being linearized were transfected into Leishmania tarentolae genome. After recombinant strains were selected, they were verified by molecular methods. After the extraction and purification of the protein using the method above, groups of mice were injected with the recombinant antigens and ODN CpG adjuvant. Eukaryotic subunit vaccines showed more effective immunization compared with prokaryotic vaccines and caused an immune system shift towards Th1 and protection. Protein expression in L. tarentolae by the constructs created in this host contains Post-Translational Modifications. The constructed protein will be significantly similar to eukaryotic proteins, considering that they are identical epitopes. More comprehensive studies aiming to improve the effectiveness of this vaccine are being conducted to improve immune profiles and immunological memory stimulation in future designs.

Evaluation of protection induced by in vitro maturated BMDCs presenting CD8+ T cell stimulating peptides after a heterologous vaccination regimen in BALB/c model against Leishmania major

Leishmaniasis is a complex vector-borne disease mediated by Leishmania parasite and a strong and long-lasting CD4⁺ Th1 and CD8⁺-T cell immunity is required to control the infection. Thus far multivalent subunit vaccines have met this requirement more promisingly. However several full protein sequences cannot be easily arranged in one construct. Instead, new emerging immune-informatics based epitope formulations surpass this restriction. Herein, we aimed to examine the protective potential of a dendritic cell based vaccine presenting epitopes to CD8⁺ and CD4⁺-T cells in combination with DNA vaccine encoding the same epitopes against murine cutaneous leishmaniasis. Immature DCs were loaded with epitopes (selected from parasite proteome) in vitro with or without CpG oligonucleotides and were used to immunize BALB/c mice. Peptide coding DNA was used to boost the system and immunological responses were evaluated after Leishmania (L.) major infectious challenge. The pre-challenge response to included epitopes was Th1 polarized which potentially lowered the infection at early time points post-challenge but not at later weeks. Collectively, DC prime-DNA boost was found to be a promising approach for Th1 polarization however the constituent epitopes undoubtedly make a significant contribution in the protection outcome of the vaccine.

Leishmania eukaryotic elongation Factor-1 beta protein is immunogenic and induces parasitological protection in mice against Leishmania infantum infection

Treatment for visceral leishmaniasis (VL) is hampered mainly by the toxicity and/or high cost of antileishmanial drugs. What is more, variability on sensitivity and/or specificity of diagnostic tests hinders effective disease management. In this context, prophylactic vaccination should be considered as a strategy to prevent disease. In the present study, immunogenicity of the Leishmania eukaryotic Elongation Factor-1 beta (EF1b) protein, classified as a Leishmania virulence factor, was evaluated in vitro and in vivo and tested, for the first time, as a vaccine candidate against Leishmania infantum infection. The antigen was administered as DNA vaccine or as recombinant protein (rEF1b) delivered in saponin. BALB/c mice immunization with a DNA plasmid and recombinant protein plus saponin induced development of specific Th1-type immunity, characterized by high levels of IFN-γ, IL-12, GM-CSF, both T cell subtypes and antileishmanial IgG2a isotype antibodies, before and after infection. This immunological response to the vaccines was corroborated further by parasitological analysis of the vaccinated and then challenged mice, which showed significant reductions in the parasite load in their liver, spleen, bone marrow and draining lymph nodes, when compared to the controls. Vaccination using rEF1b/saponin induced a more robust Th1 response and parasitological protection when compared to the DNA vaccine. Furthermore, in vitro analysis of lymphoproliferation, IFN-γ and IL-10 levels in human PBMC cultures showed as well development of a specific Th1-type response. In conclusion, data suggest that EF1b could be a promising vaccine candidate to protect against L. infantum infection.

Epitope Selection for Fighting Visceral Leishmaniosis: Not All Peptides Function the Same Way

Visceral leishmaniosis (VL) caused by Leishmania infantum is a disease with an increasing prevalence worldwide. Treatments are expensive, toxic, and ineffective. Therefore, vaccination seems to be a promising approach to control VL. Peptide-based vaccination is a useful method due to its stability, absence of local side effects, and ease of scaling up. In this context, bioinformatics seems to facilitate the use of peptides, as this analysis can predict high binding affinity epitopes to MHC class I and II molecules of different species. We have recently reported the use of HisAK70 DNA immunization in mice to induce a resistant phenotype against L. major, L. infantum, and L. amazonensis infections. In the present study, we used bioinformatics tools to select promising multiepitope peptides (HisDTC and AK) from the polyprotein encoded in the HisAK70 DNA to evaluate their immunogenicity in the murine model of VL by L. infantum. Our results revealed that both multiepitope peptides were able to induce the control of VL in mice. Furthermore, HisDTC was able to induce a better cell-mediated immune response in terms of reduced parasite burden, protective cytokine profile, leishmanicidal enzyme modulation, and specific IgG2a isotype production in immunized mice, before and after infectious challenge. Overall, this study indicates that the HisDTC chimera may be considered a satisfactory tool to control VL because it is able to activate a potent CD4+ and CD8+ T-cell protective immune responses.

A Canine-Directed Chimeric Multi-Epitope Vaccine Induced Protective Immune Responses in BALB/c Mice Infected with Leishmania infantum

Leishmaniases are complex vector-borne diseases caused by intracellular parasites of the genus Leishmania. The visceral form of the disease affects both humans and canids in tropical, subtropical, and Mediterranean regions. One health approach has suggested that controlling zoonotic visceral leishmaniasis (ZVL) could have an impact on the reduction of the human incidence of visceral leishmaniasis (VL). Despite the fact that a preventive vaccination could help with leishmaniasis elimination, effective vaccines that are able to elicit protective immune responses are currently lacking. In the present study, we designed a chimeric multi-epitope protein composed of multiple CD8⁺ and CD4⁺ T cell epitopes which were obtained from six highly immunogenic proteins previously identified by an immunoproteomics approach, and the N-termini of the heparin-binding hemagglutinin (HBHA) of Mycobacterium tuberculosis served as an adjuvant. A preclinical evaluation of the candidate vaccine in BALB/c mice showed that when it was given along with the adjuvant Addavax it was able to induce strong immune responses. Cellular responses were dominated by the presence of central and effector multifunctional CD4⁺ and CD8⁺ T memory cells. Importantly, the vaccination reduced the parasite burden in both short-term and long-term vaccinated mice challenged with Leishmania infantum. Protection was characterized by the continuing presence of IFN-γ⁺TNFα⁺-producing CD8⁺ and CD4⁺ T cells and increased NO levels. The depletion of CD8⁺ T cells in short-term vaccinated mice conferred a significant loss of protection in both target organs of the parasite, indicating a significant involvement of this population in the protection against L. infantum challenge. Thus, the overall data could be considered to be a proof-of-concept that the design of efficacious T cell vaccines with the help of reverse vaccinology approaches is possible.

Evaluation of the protective efficacy of a Leishmania protein associated with distinct adjuvants against visceral leishmaniasis and in vitro immunogenicity in human cells

The treatment against visceral leishmaniasis (VL) presents problems, mainly related to the toxicity and/or high cost of the drugs. In this context, a prophylactic vaccination is urgently required. In the present study, a Leishmania protein called LiHyE, which was suggested recently as an antigenic marker for canine and human VL, was evaluated regarding its immunogenicity and protective efficacy in BALB/c mice against Leishmania infantum infection. In addition, the protein was used to stimulate peripheral blood mononuclear cells (PBMCs) from VL patients before and after treatment, as well as from healthy subjects. Vaccination results showed that the recombinant (rLiHyE) protein associated with liposome or saponin induced effective protection in the mice, since significant reductions in the parasite load in spleen, liver, draining lymph nodes, and bone marrow were found. The parasitological protection was associated with Th1-type cell response, since high IFN-γ, IL-12, and GM-CSF levels, in addition to low IL-4 and IL-10 production, were found. Liposome induced a better parasitological and immunological protection than did saponin. Experiments using PBMCs showed rLiHyE-stimulated lymphoproliferation in treated patients' and healthy subjects' cells, as well as high IFN-γ levels in the cell supernatant. In conclusion, rLiHyE could be considered for future studies as a vaccine candidate against VL.

Liposomal Formulation of ChimeraT, a Multiple T-Cell Epitope-Containing Recombinant Protein, Is a Candidate Vaccine for Human Visceral Leishmaniasis

Background: Leishmaniases are neglected diseases caused by infection with Leishmania parasites and there are no human vaccines in use routinely. The purpose of this study was to examine the immunogenicity of ChimeraT, a novel synthetic recombinant vaccine against visceral leishmaniasis (VL), incorporated into a human-compatible liposome formulation. Methods: BALB/c mice were immunized subcutaneously with ChimeraT/liposome vaccine, ChimeraT/saponin adjuvant, or ChimeraT/saline and immune responses examined in vitro and in vivo. Results: Immunization with the ChimeraT/liposome formulation induced a polarized Th1-type response and significant protection against L. infantum infection. ChimeraT/liposome vaccine stimulated significantly high levels of interferon (IFN)-γ, interleukin (IL)-12, and granulocyte macrophage-colony stimulating factor (GM-CSF) cytokines by both CD4 and CD8 T-cells, with correspondingly lower levels of IL-4 and IL-10 cytokines. Induced antibodies were predominantly IgG2a isotype, and homologous antigen-stimulated spleen cells produced significant nitrite as a proxy for nitric oxide (NO). Furthermore, we examined a small number of treated VL patients and found higher levels of circulating anti-ChimeraT protein IgG2 antibodies, compared to IgG1 levels. Conclusions: Overall, the liposomal formulation of ChimeraT induced a protective Th1-type immune response and thus could be considered in future studies as a vaccine candidate against human VL.

Landscape of ubiquitination events that occur in host skin in response to tick (Haemaphysalis longicornis) bitten

Ticks are major parasites of domestic livestock, wildlife, and humans. After a tick bite, diverse cutaneous manifestations initially occur in the bitten area in the host. In this study, a label-free proteomics approach was applied to identify the differentially ubiquitinated proteins (DUPs) induced by tick-bitten in the skin. In total, 113 proteins were ubiquitinated in rabbit skin during tick bitten period, among which the ubiquitination levels of 43 proteins were altered. These DUPs in skin subjected to tick-bitten were enriched in metabolic processes, immune processes, and protein degradation processes. Bioinformatic analysis suggested that tick bitten may regulate the glycolysis pathway in host skin via differential ubiquitination of GAPDH, HK1 and TPI1, while regulate the ubiquitin-proteasome system, the MHC-I and MHC-II antigen-presenting pathways, and the HIF-1 signaling pathway via differential ubiquitination of MEK1, PSMC3, PSMA6, MHC-II and PSMD1. Moreover, PSMC3, PSMA6, PSMD1 and MEK1 were demonstrated as novel targets of ubiquitination. This study provides the first overview of ubiquitination in host skin affected by tick bitten and broadens our knowledge of the molecular mechanism involved in tick bitten.

Detection of Antigen-specific T cells in Spleens of Vaccinated Mice Applying 3[H]-Thymidine Incorporation Assay and Luminex Multiple Cytokine Analysis Technology

For many infectious diseases T cells are an important part of naturally acquired protective immune responses, and inducing these by vaccination has been the aim of much research. Here, we describe a protocol for the analysis of vaccine-induced antigen-specific immune responses. For this purpose, cells of whole spleens obtained from vaccinated BALB/c mice were ex vivo stimulated with the antigen incorporated in the vaccine. Evaluation and characterization of vaccine-induced adaptive T cell responses was performed by assaying spleen cell proliferation through radioactive ³[H]-thymidine incorporation and multiplex cytokine analysis of IL-2, IFN-γ and TNFα in supernatants from spleen cell suspensions. This protocol can be very useful as a starting point for assessing vaccine-induced memory T cell populations in pre-clinical studies.

Silencing SOCS1 via Liposome-Packed siRNA Sustains TLR4-Ligand Adjuvant

Infectious diseases remain one of the leading causes of death worldwide. Vaccination is a powerful instrument to avert a variety of those by inducing a pathogen-specific immune response and ensure a long-lasting protection against the respective infection. Nevertheless, due to increasing numbers of immunocompromised patients and emergence of more aggressive pathogens existing vaccination techniques are limited. In our study we investigated a new strategy to strengthen vaccine adjuvant in order to increase immunity against infectious diseases. The strategy is based on an amplification of Toll-like receptor 4 (TLR4) -induced activation of antigen-presenting cells (APCs) by turning off a powerful endogenous inhibitor of APC-activation. TLR4 signaling induces the release of cytokines that bind autocrine and paracrine to receptors, activating the Janus kinase (JAK) 2/signal transducers and activators of transcription (STAT) 3 cascade. Subsequently, STAT3 induces expression of suppressor of cytokine signaling (SOCS) 1 that terminates the inflammatory response. In the approach, TLR4-adjuvant monophosphoryl lipid A (MPLA)-stimulated monocyte-activation is reinforced and sustained by silencing SOCS1 via lipid nanoparticle-enclosed siRNA (L-siRNA). L-siRNA is transported into primary cells without any toxic side effects and protected from early degradation. Through lipid core-embedded functional groups the lipid particle escapes from endosomes and releases the siRNA when translocated into the cytoplasm. SOCS1 is potently silenced, and SOCS1-mediated termination of NFκB signaling is abrogated. Consequently, the MPLA-stimulated activation of APCs, monitored by release of pro-inflammatory cytokines such as IL-6, TNFα, and IL-1β, upregulation of MHC class II molecules and costimulatory CD80/CD86 is strongly enhanced and prolonged. SOCS1-silenced APCs, pulsed with liposomal tetanus light chain toxin (TeTxLC) antigen, activate autologous T cells much more intensively than SOCS1-expressing cells. Importantly, expansion of cocultured CD4⁺ as well as CD8⁺ T cells is remarkably enhanced. Furthermore, our results point toward a broad T helper cell response as TH1 typical as well as TH2 characteristic cytokines are elevated. Taken together, this study in the human system comprises a translational potential to develop more effective vaccines against infectious diseases by inhibition of the endogenous negative-feedback loop in APCs.