Induction Of Humoral Immune Responses Research Articles

Chemoattractant receptor signaling in humoral immunity.

Efficient induction of humoral immune responses depends on orchestrated migration of B cells within lymphoid organs, which is governed by G protein-coupled receptors (GPCRs) responding to chemoattractants, represented by chemokines. After ligand binding, GPCRs are phosphorylated by different GPCR kinases (GRKs) at distinct sites on the receptor C termini, which dictates functional outcomes of β-arrestin-mediated signaling, ranging from receptor inactivation to effector molecule activation. However, the molecular mechanisms by which individual GRKs are selectively targeted to GPCRs have been poorly understood. Our recent study revealed that a protein complex consisting of copper metabolism MURR1 domain-containing (COMMD) 3 and 8 (COMMD3/8 complex) functions as an adaptor that recruits a specific GRK to chemoattractant receptors and plays an important role in the control of B cell migration during humoral immune responses. In this review, we summarize the current understanding of chemoattractant receptor signaling in the context of humoral immunity and discuss the potential of the COMMD3/8 complex as a therapeutic target for autoimmune diseases.

Steady-state Langerhans cells induce Tfh and B cell responses through a type I interferon and IL-6 independent mechanism

Abstract Langerhans cells (LCs) can support the induction of antibody responses against foreign antigens without a danger signal. These findings contradict the danger model proposed to define how the adaptive immune responses are mounted. Deciphering how LCs, and some other dendritic cell subsets, support adaptive immune responses in steady-state could lead to a better understanding of how immune responses are induced and regulated and, ultimately, to developing more efficient immunotherapeutics for autoimmune- and infectious diseases. Here we used a well-established steady-state antigen targeting model to dissect the mechanism by which LCs support T follicular helper (Tfh) cells and antibody responses. Using bone marrow chimeras, Cre-lox system, and blocking antibodies, we found that IL-6, which is critical in the induction of Tfh cells and antibody responses in inflammatory conditions, played no role in LC-induced adaptive immune responses at steady-state. Type I interferon signaling was also dispensable in this regard. However, our preliminary data support that induction of humoral immune responses by steady-state LCs depends on membrane-bound co-stimulatory molecules, such as ICOS/ICOS-L. Thus, these data suggest that adaptive immune responses against foreign antigens in the absence of inflammation are generated through a distinct mechanism that likely does not involve inflammatory cytokines. Supported by grants from NIH R01AI146420 and Thomas Jefferson University startup funds.

Ocrelizumab Concentration Is a Good Predictor of SARS-CoV-2 Vaccination Response in Patients with Multiple Sclerosis.

Ocrelizumab, an anti-CD20 monoclonal antibody, counteracts induction of humoral immune responses after severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) vaccinations in patients with multiple sclerosis (MS). We aimed to assess if serum ocrelizumab concentration measured at the time of vaccination could predict the humoral response after SARS-CoV-2 vaccination. In 52 patients with MS, we found ocrelizumab concentration at the time of vaccination to be a good predictor for SARS-CoV-2 IgG anti-RBD titers after vaccination (comparable to B-cell count). As the course of ocrelizumab concentration may be predicted using pharmacokinetic models, this may be a superior biomarker to guide optimal timing for vaccinations in B-cell depleted patients with MS. ANN NEUROL 2023;93:103-108.

Nanocurcumin as an adjuvant in killed Toxoplasma gondii vaccine formulation: An experience in BALB/c mice

Toxoplasma gondii (T. gondii) remains as one of the controversial infections in the world. T. gondii is an important obligate intracellular protozoan parasite in the immune-deficient patients and pregnant women, sometimes leading to death and abortion, respectively. Herein, the adjuvant activity of nanocurcumin was assessed in the T. gondii killed vaccine model in BALB/c mice. In this study, 144 BALB/c mice were included in 8 groups and administered with different regimens of the vaccine; vac+30, 20 mg/kg of curcumin and nanocurcumin, vac + Freund's adjuvant, killed vac, vac + Alum adjuvant, and PBS via the subcutaneous route of immunization for three times with two-week intervals. Two weeks after the last immunization, the splenocytes' culture supernatant was evaluated for IL-4, IFN-γ, IL-2 and TNF-α cytokines and IFN-γ/IL-4, IFN-γ/TNF-α, and IL-2/IL-4 cytokine ratios using commercial ELISA kits. Specific total IgG antibodies, IgG1, and IgG2a were assessed with an optimized ELISA. Then the survival rate was determined 10 days after the experimental challenge. The results showed that the vaccine formulation in nanocurcumin at 20 mg/kg significantly increases IFN-γ cytokine and IFN-γ/IL4, IFN-γ/TNFα, and IL-2/IL4 ratios versus the vaccine formulated in curcumin, killed vaccine, and PBS group. In addition, specific total IgG antibody response showed that the vaccine formulated in nanocurcumin was more potent than that formulated in curcumin in the induction of humoral immune responses. Furthermore, results from the experimental challenge showed that nanocurcumin at a dose of 20 mg/kg could promote the life span of mice approximately by 12% versus the killed vaccine group. The present study showed that nanocurcumin in the vaccine formulation not only is more bioactive than curcumin in the modulation of cellular and humoral immune responses, but also provides more protectivity rate in the vaccinated mice on the killed T. gondii vaccine model. It seems that nanocurcumin can be used as an immunomodulator in vaccine formulation or as part of a complex adjuvant.

Use of Optical In Vivo Imaging to Monitor and Optimize Delivery of Novel Plasmid-Launched Live-Attenuated Vaccines.

Plasmid-launched live-attenuated vaccines (PLLAV) are a modality of next-generation vaccines with the promise to combine the benefits of both (1) the potency of live vaccines and (2) the ease of production, quality control, and thermal stability of classical DNA vaccines. Using the live yellow fever 17D (YF17D) vaccine as paradigm, we establish a bioluminescence-based in vivo imaging approach that allows to rapidly monitor and optimize the dose and route of delivery of such PLLAV in a mouse model of YF17D immunization. Vaccine virus replication thus launched in the skin of vaccinated mice can be quantified by the light emitted, benchmarked to signals originating from a YF17D reporter virus and finally correlated to the induction of humoral immune responses to the yellow fever virus.

Toll-Like Receptor 4 Regulates Rabies Virus-Induced Humoral Immunity through Recruitment of Conventional Type 2 Dendritic Cells to Lymph Organs.

Rabies, caused by rabies virus (RABV), is fatal to both humans and animals around the world. Effective clinical therapy for rabies has not been achieved, and vaccination is the most effective means of preventing and controlling rabies. Although different vaccines, such as live attenuated and inactivated vaccines, can induce different immune responses, different expressions of pattern recognition receptors (PRRs) also cause diverse immune responses. Toll-like receptor 4 (TLR4) is a pivotal PRR that induces cytokine production and bridges innate and adaptive immunity. Importantly, TLR4 recognizes various virus-derived pathogen-associated molecular patterns (PAMPs) and virus-induced damage-associated molecular patterns (DAMPs), usually leading to the activation of immune cells. However, the role of TLR4 in the humoral immune response induced by RABV has not yet been revealed. Based on TLR4-deficient (TLR4-/-) and wild-type (WT) mouse models, we report that TLR4-dependent recruitment of the conventional type 2 dendritic cells (CD8α- CD11b+ cDC2) into secondary lymph organs (SLOs) is critical for antigen presentation. cDC2-initiated differentiation of follicular helper T (Tfh) cells promotes the proliferation of germinal center (GC) B cells, the formation of GCs, and the production of plasma cells (PCs), all of which contribute to the production of RABV-specific IgG and virus-neutralizing antibodies (VNAs). Collectively, our work demonstrates that TLR4 is necessary for the recruitment of cDC2 and for the induction of RABV-induced humoral immunity, which is regulated by the cDC2-Tfh-GC B axis. IMPORTANCE Vaccination is the most efficient method to prevent rabies. TLR4, a well-known immune sensor, plays a critical role in initiating innate immune response. Here, we found that TLR4-deficient (TLR4-/-) mice suppressed the induction of humoral immune response after immunization with rabies virus (RABV), including reduced production of VNAs and RABV-specific IgG compared to that occurred in wild-type (WT) mice. As a consequence, TLR4-/- mice exhibited higher mortality than that of WT mice after challenge with virulent RABV. Importantly, further investigation found that TLR4 signaling promoted the recruitment of cDC2 (CD8α+ CD11b-), a subset of cDCs known to induce CD4+ T-cell immunity through their MHC-II presentation machinery. Our results imply that TLR4 is indispensable for an efficient humoral response to rabies vaccine, which provides new insight into the development of novel rabies vaccines.

GC-Tfh cell induction by Langerhans cells in steady-state is antigen-dose dependent and IL-6 independent.

Abstract We previously compared the contributions of different skin dendritic cell subsets in the induction of humoral immune responses. We found that antigen delivery without adjuvants to Langerhans cells (LCs) through the c-type lectin receptor Langerin, unlike cDC1, induces germinal center T follicular helper cells (GC-Tfhs), GC B cells, and high antibody titers. We also showed that targeting LCs with higher antigen dose induced significantly lower B cell responses and antibody titers. To better understand the role of antigen dose in this response, we assessed the T cell responses following targeting of LCs with different amounts of antigen. In accordance with the B cell responses, we found that GC-Tfh cell formation was also antigen dose-dependent. Using two-complementary approaches targeting IL-6-deficient LCs and targeting LCs in mice treated with neutralizing anti-IL-6 antibody, we showed that LCs induced GC-Tfh cells’ formation is an IL-6 independent fashion. In summary, this study shows that targeting LCs at steady-state induces the formation of GC-Tfh cells through an antigen-dose dependent and IL-6 independent mechanism.

Protective Efficacy of Different Live Attenuated Infectious Bronchitis Virus Vaccine Combination against Challenge with GI11 (BR-Type) Strain

The infectious bronchitis virus (IBV) is an avian coronavirus that causes a highly contagious disease that results in substantial economic losses to the poultry industry worldwide. The prevention is mostly based on biosecurity measures and vaccination. The vaccination programs are defined by epidemiological status and cross-immunity provided against different serotypes. Programs using vaccine combinations can be designed to increase protection. We conducted an experimental study to compare two vaccine programs on protection against a virulent strain belonging to the GI-11 genotype (BR-type) isolated in Brazil using two different Mass-type vaccines combined with a BR-type live vaccine. Two groups of commercial chicks were vaccinated at day-1 using two commercially available Mass-type vaccines + BR-type vaccine. They were challenged intranasally at 28-day using 104 EID50/0.1 microliter/chick of wild-type G11 IBV (IBV/24W). Ciliostasis, macroscopic and microscopic lesion scores were evaluated at 4 and 11-days post vaccination (dpv) and 5 days post infection (dpi) and not showed differences between vaccinated groups. MLV+BR-Type group presented highest amount of BR strain vaccine and lowest amount of Mass strain vaccine in tracheal and cloacal swabs at 4 and 11 dpv. In the other hand, the Ma5+BR-type group showed fewer BR-type positive in both samples tested. After challenge, MLV+BR group showed higher titer of antibody measured by ELISA. These results suggest that the selection of a Mass-type vaccine strain can impact directly in the BR vaccine replication, when used associated, and consequently the induction of humoral immune response. Despite that, both protocols provided protection against the challenge with G11 strain.

Lipid-based vaccine nanoparticles for induction of humoral immune responses against HIV-1 and SARS-CoV-2

The current health crisis of corona virus disease 2019 (COVID-19) highlights the urgent need for vaccine systems that can generate potent and protective immune responses. Protein vaccines are safe, but conventional approaches for protein-based vaccines often fail to elicit potent and long-lasting immune responses. Nanoparticle vaccines designed to co-deliver protein antigens and adjuvants can promote their delivery to antigen-presenting cells and improve immunogenicity. However, it remains challenging to develop vaccine nanoparticles that can preserve and present conformational epitopes of protein antigens for induction of neutralizing antibody responses. Here, we have designed a new lipid-based nanoparticle vaccine platform (NVP) that presents viral proteins (HIV-1 and SARS-CoV-2 antigens) in a conformational manner for induction of antigen-specific antibody responses. We show that NVP was readily taken up by dendritic cells (DCs) and promoted DC maturation and antigen presentation. NVP loaded with BG505.SOSIP.664 (SOSIP) or SARS-CoV-2 receptor-binding domain (RBD) was readily recognized by neutralizing antibodies, indicating the conformational display of antigens on the surfaces of NVP. Rabbits immunized with SOSIP-NVP elicited strong neutralizing antibody responses against HIV-1. Furthermore, mice immunized with RBD-NVP induced robust and long-lasting antibody responses against RBD from SARS-CoV-2. These results suggest that NVP is a promising platform technology for vaccination against infectious pathogens.

Induction of humoral immune responses and inhibition of metastasis in mice by a VEGF peptide-based vaccine.

Objective(s):Blocking of vascular endothelial growth factor (VEGF) plays a pivotal role in inhibition of metastasis and is a target for development of anti-angiogenic agents. In this study, a peptide-based vaccine was designed and its potential for induction of humoral immune responses, generation of neutralizing antibodies, inhibition of tumor growth and metastasis was determined.Materials and Methods:With online bioinformatics tools, a fragment of the VEGF-A was selected for a peptide-based vaccine. To enhance its antigenicity, the peptide was conjugated with Keyhole limpet hemocyanin and used to immunize mice. Then, the polyclonal anti-VEGF antibody titer was measured and its effect on proliferation of HUVEC cell line was investigated by MTT assay. Finally, we checked the effect of the peptide on tumor growth, metastasis, and survival rates in a mouse model of cancer.Results:The bioinformatics analysis of the selected region confirmed dis-similarity of the peptide with any other human protein and its acceptable antigenicity to stimulate a tumor-specific humoral response. Anti-VEGF antibody titers were significantly greater in vaccinated mice than in controls. IgG antibody from mice immunized with recombinant VEGF-A inhibited HUVEC proliferation (P<0.0001). Tumors in vaccinated mice were significantly smaller than those in controls. Moreover, metastasis was reduced and survival rates increased in the vaccinated group.Conclusion:Production of high-titer antibody against the peptide vaccine indicated that the peptide has the potency to be used as a peptide-based vaccine for humoral inhibition of tumor growth and metastasis. The efficacy of the peptide should be further tested in primate models.

A PBMC-Based System to Assess Human T Cell Responses to Influenza Vaccine Candidates In Vitro.

Vaccine development is an expensive and time-consuming process that heavily relies on animal models. Yet, vaccine candidates that have previously succeeded in animal experiments often fail in clinical trials questioning the predictive value of animal models. Alternative assay systems that can add to the screening and evaluation of functional characteristics of vaccines in a human context before embarking on costly clinical trials are therefore urgently needed. In this study, we have established an in vitro system consisting of long-term cultures of unfractionated peripheral blood mononuclear cells (PBMCs) from healthy volunteers to assess (recall) T cell responses to vaccine candidates. We observed that different types of influenza vaccines (whole inactivated virus (WIV), split, and peptide vaccines) were all able to stimulate CD4 and CD8 T cell responses but to different extents in line with their reported in vivo properties. In-depth analyses of different T cell subsets revealed that the tested vaccines evoked mainly recall responses as indicated by the fact that the vast majority of the responding T cells had a memory phenotype. Furthermore, we observed vaccine-induced activation of T follicular helper cells, which are associated with the induction of humoral immune responses. Our results demonstrate the suitability of the established PBMC-based system for the in vitro evaluation of memory T cell responses to vaccines and the comparison of vaccine candidates in a human immune cell context. As such, it can help to bridge the gap between animal experiments and clinical trials and assist in the selection of promising vaccine candidates, at least for recall antigens.

TIR-TLR7 as a Molecular Adjuvant: Simultaneous Enhancing Humoral and Cell-Mediated Immune Responses Against Inactivated Infectious Bursal Disease Virus.

Despite the robust induction of humoral immune responses, a limitation of many adjuvants is their weak stimulation of cellular immunity. The development of synthetic gene-encoding adjuvants for simultaneous induction of both humoral and cell-mediated immune responses is under study. In this study, we examined the impact of toll/interleukin-1 receptor (TIR) domain of toll-like receptor 7 (TLR7) as molecular adjuvants on potency of inactivated infectious bursal disease (IBD) vaccines. A total of 60 specific pathogen-free week-old chicks were randomized grouped to receive either TIR-TLR7-adjuvanted IBD-inactivated vaccine or inactivated IBD antigen along with an unvaccinated control. Serum antibody titers were measured to estimate the humoral immunity, as well as lymphocyte proliferation activity for cellular immune responses. The protection was estimated after challenge with a very virulent IBD virus (IBDV) strain at 4 weeks postvaccination. The results indicated that one dose of IBD/TIR-TLR7 vaccine induced specific antibody responses, whereas a lower response after administration of inactivated IBD antigen was observed. The stimulation of splenocytes results indicated that the TIR-TLR7 adjuvanted IBD vaccine is capable of modulating cell-mediated immune response in treated chickens. A full protection against IBDV infection was achieved by injection of one dose IBD/TIR-TLR7 vaccine in the challenge trial. This study demonstrated that codelivery of TIR-TLR7 with inactivated IBD antigen resulted in simultaneous enhancing immune responses against IBD.

Formulation of HBs antigen in Montanide ISA266 shows superiority to commercial HBsAg vaccine in the induction of humoral immune responses.

In the present study, a new formulation of HBsAg vaccine was developed and compared with a commercial peer. Vaccination of hepatitis B infection has been an unavoidable affair since the 1980s, though it has numerous limitations such as inefficacy in the induction of cellular immune responses. To address these limitations, research on novel formulations is necessary to develop a superior formulation with the potency of induction of both cellular and humoral immune responses. HBsAg was formulated in oil-in-water adjuvant Montanide ISA-266 (5 µg/dose) using homogenizer. Balb/C mice were then immunized three times at days 0, 14, and 28 with HBsAg/Montanide ISA-266 or HBsAg/alum with proper control groups. Two weeks after the last immunization, immunological parameters including IL-2, IL-4, TNF-α, IFN-γ, total IgG and IgG1/IgG2a isotypes were assessed by ELISA. The results demonstrated that the formulation of HBsAg with Montanide ISA-266 enhanced humoral immune responses versus the commercial vaccine and control groups. No significant difference in terms of Th1 pattern was found between HBsAg/Montanide ISA-266 and the commercial vaccine. Formulation of HBsAg with an oil-based adjuvant may be useful for the induction of a more potent humoral immune response compared to the commercially available HBV vaccine.

Alum-functionalized graphene oxide nanocomplexes for effective anticancer vaccination

Aluminum-based adjuvant (e.g., aluminum oxyhydroxide (AlO(OH), known as the commercial Alhydrogel® (Alum)) is the first adjuvant to be used in human vaccines. Although Alum shows a robust induction of antibody-mediated immunity, its weak stimulation of cell-mediated immunity makes it a questionable adjuvant for cancer immunotherapy. Herein, we described a novel formulation of Alum-based adjuvant by preparing AlO(OH)-modified graphene oxide (GO) nanosheets (GO-AlO(OH)), which, in addition to maintaining the induction of humoral immune response by AlO(OH), could further elicit the cellular immune response by GO. Similar to Alum, GO-AlO(OH) vaccine formulation could be constructed by the incorporation of antigen using a facile mixing/adsorption approach. Antigen-loaded GO-AlO(OH) nanocomplexes facilitated cellular uptake and cytosolic release of antigens and promoted DC maturation, thereby eliciting higher antigen-specific IgG titers, inducing robust CD4+ and CD8+ T lymphocyte response, and inhibiting tumor growth in vivo. Furthermore, by employing tumor cell lysate-based cancer vaccines, GO-AlO(OH) nanocomplexes led to significant inhibition of tumor growth and can be implemented as a personalized treatment strategy for cancer vaccine development. Overall, GO-AlO(OH) nanocomplexes described herein may serve as a facile and efficient approach for effective anticancer vaccination. Statement of SignificanceHerein, we described a novel formulation of aluminum-based adjuvant by preparing aluminum oxyhydroxide (AlO(OH)) (known as “Alum”)-modified graphene oxide (GO) nanocomplexes (GO-AlO(OH)), which, in addition to maintaining the induction of humoral immune response by AlO(OH), could further elicit the cellular immune response by GO. GO-AlO(OH) nanocomplexes can be prepared easily and in large scale by a chemical precipitation method. Similar to “Alum,” antigen-loaded GO-AlO(OH) vaccine formulation could be constructed by the incorporation of antigen using a facile mixing/adsorption approach. The very simple and reproductive preparation process of vaccines and the powerful ability to raise both humoral and cellular immune responses provide a novel approach for improving cancer immunotherapy efficacy.

Clinical and Immunological Response to Sublingual Vaccination for the Prevention of Recurrent Urinary Tract Infections in Kidney Transplant Patients

Introduction Frequent antibiotic use in urinary tract infections (UTI) is associated with an elevated risk of adverse events as well as developing multidrug resistant UTI. Sublingual vaccination with Uromune® has been shown to reduce the frequency of UTI in patients suffering from recurrent urinary tract infections (rUTI) in the general population. The aim of this study was to describe the clinical and immunological response to this vaccine in kidney transplant recipients with rUTI. Material and Method Sublingual vaccination with Uromune® was prescribed to kidney transplant patients who met criteria for rUTI (≥2 UTI in the previous 6 months or ≥ 3 UTI in the previous year), administering 2 daily sublingual puffs for 6 months. Patients in the first post-transplant year were excluded. After 1 year of follow-up, the number of UTI episodes and severe episodes requiring hospital admittance were compared to those in the previous year. Changes in renal function and anti-HLA antibodies were measured. Humoral and cellular immune response were monitored by measuring clonal B and T-lymphocyte populations before vaccination and after 3 and 6 months of vaccination. Results 43 kidney transplant recipients with rUTI completed sublingual vaccination with Uromune® for 6 months, age 56.2±15.0 years, median transplant duration 6.0 years (interquartile range (IQR) 3.7-10.5), 86% females, 32.6% had polycystic kidney disease, 32.6% diagnosed with diabetes mellitus, 39.5% had urinary tract structural or functional abnormalities. The mean incidence of UTI decreased from 4.2 to 2.7 episodes per year (CI 95% 0.9-2.2, p<0,001). After one year, 16.3% of patients were completely free from UTI and 46.5% had fewer infections. After 6 months from vaccination, there was an increase in total B lymphocytes from 6.9% (IQR 3.2-13.6) to 8% (IQR 4.4-15.6)(p=0.012), and in memory B cells from 34.3% (IQR 14.1-48.8) to 40.7% (IQR 30.8-54)(p=0.002). There was a decrease in transitional B lymphocytes from 4.7% (IQR 2-9.7) to 1.1% (IQR 0.3-2.5)(p<0.001), in switched memory B cells from 29.6% (IQR 15.6-45) to 14.6% (IQR 7.6-29.3)(p=0.038), and in plasmablasts from 8.6% (IQR 2.1-31.4) to 1.2% (IQR 0.5-3.4)(p=0.009). In vaccine responders, total B lymphocytes increased from 8.6% (IQR 3.7-15.5) to 11.6% (IQR 5.3-16.7)(p=0.005), while plasmablasts decreased from 13% (IQR 2.4-33.1) to 0.75% (IQR 0.3-2.1)(p=0.028) and switched memory B cells from 19.6% (7.3-44.6) to 13.9% (7.2-18). These changes were not found in vaccine non-responders. There were no significant differences in clonal T-cell populations between both groups. No significant changes in serum creatinine or development of new anti-HLA antibodies were found. Conclusions Sublingual administration of polybacterial vaccine Uromune® can reduce the frequency of UTI in kidney transplant patients with rUTI through the induction of humoral immune response. In our study, no changes in renal function or development of new anti-HLA antibodies were found.

CD4+ levels control the odds of induction of humoral immune responses to tracer doses of therapeutic antibodies.

Rapidly increasing number of therapeutic antibodies are being repurposed to imaging probes for noninvasive diagnosis, as well as monitoring during treatment or disease recurrence. Though antibody-based imaging involves tracer doses (~3 log lower than therapeutic doses), and immune responses are severely reduced in patients with impaired immunity, formation of anti-tracer antibodies (ATA) has been observed hampering further diagnostic monitoring. Here, we explored the potential to develop humoral responses to intravenously administered tracer dose of a monoclonal antibody F(ab΄)2 fragment, and associated with host related immune measures in 49 rhesus macaques categorized into healthy (uninfected controls), SIV-progressors, SIV non-progressors, or total body irradiated (TBI). Antibody fragment administered in tracer amount (~100μg) induced immune responses with significantly lower odds in SIV-progressors or TBI macaques (P<0.005) as compared to healthy animals. Peripheral blood (PB) CD4+ cell counts, but not CD20+ cell levels, were associated with significantly higher risk of developing a humoral response (P<0.001). Doubling the PB CD4+ counts is associated with an odds ratio of developing an immune response of 1.73. Among SIV-infected animals, CD4+ cell count was a stronger predictor of immune response than plasma SIV-RNA levels. Both SIV-progressors and TBI macaques showed higher odds of responses with increasing CD4+ counts, however when compared to healthy or SIV non-progressors with similar CD4+ count, they were still functionally incompetent in generating a response (P<0.01). Moreover, presence of ATA in systemic circulation altered the in vivo biodistribution by increasing hepatic uptake and decreasing plasma radiotracer clearance, with minimal to no binding detected in targeted tissues.

Antibody responses to P. falciparum blood stage antigens and incidence of clinical malaria in children living in endemic area in Burkina Faso

BackgroundHigh parasite-specific antibody levels are generally associated with low susceptibility to Plasmodium falciparum malaria. This has been supported by several studies in which clinical malaria cases of P. falciparum malaria were reported to be associated with low antibody avidities. This study was conducted to evaluate the role of age, malaria transmission intensity and incidence of clinical malaria in the induction of protective humoral immune response against P. falciparum malaria in children living in Burkina Faso.MethodsWe combined levels of IgG and IgG subclasses responses to P. falciparum antigens: Merozoite Surface Protein 3 (MSP3), Merozoite Surface Protein 2a (MSP2a), Merozoite Surface Protein 2b (MSP2b), Glutamate Rich Protein R0 (GLURP R0) and Glutamate Rich Protein R2 (GLURP R2) in plasma samples from 325 children under five (05) years with age, malaria transmission season and malaria incidence.ResultsWe notice higher prevalence of P. falciparum infection in low transmission season compared to high malaria transmission season. While, parasite density was lower in low transmission than high transmission season. IgG against all antigens investigated increased with age. High levels of IgG and IgG subclasses to all tested antigens except for GLURP R2 were associated with the intensity of malaria transmission. IgG to MSP3, MSP2b, GLURP R2 and GLURP R0 were associated with low incidence of malaria. All IgG subclasses were associated with low incidence of P. falciparum malaria, but these associations were stronger for cytophilic IgGs.ConclusionsOn the basis of the data presented in this study, we conclude that the induction of humoral immune response to tested malaria antigens is related to age, transmission season level and incidence of clinical malaria.

Induction of Humoral Immune Response by 66 kDa Protein and Amplification of Gene present by using Polymerase Chain Reaction

Malaria is one of the most dreaded vector borne disease caused by apicomplexan parasite, of the genus Plasmodium. In the present study the gene which encodes 66kDa protein in rodent malaria parasite, Plasmodium berghei, was cloned. Rodent malaria parasite, Plasmodium berghei (NK-65), was found lethal to white Swiss mice (BALB/c). The immunogenicity and protective efficacy of purified 66 kDa protein was evaluated both in vitro and in vivo. Mice immunized with 66 kDa protein induced a strong humoral immune response, revealing role of 66 kDa in malaria control. Genomic DNA of P. berghei was isolated from cell free parasite. Genomic DNA serves as a template for isola on of gene encoding 66 kDa protein. Further, the gene was amplified by using polymerase chain reaction. The amplified DNA fragment of 1717 bp was extracted from agarose gel and puri ed. The purified gene was ligated to a cloning vector for cloning procedure by TA-cloning mechanism. Results of this study provide evidence that 66 kDa protein is highly immunogenic during experimental infec on in rodents and such an gen will be a suitable candidate malaria vaccine.

Induction of humoral immune response to multiple recombinant Rhipicephalus appendiculatus antigens and their effect on tick feeding success and pathogen transmission

BackgroundRhipicephalus appendiculatus is the primary vector of Theileria parva, the etiological agent of East Coast fever (ECF), a devastating disease of cattle in sub-Saharan Africa. We hypothesized that a vaccine targeting tick proteins that are involved in attachment and feeding might affect feeding success and possibly reduce tick-borne transmission of T. parva. Here we report the evaluation of a multivalent vaccine cocktail of tick antigens for their ability to reduce R. appendiculatus feeding success and possibly reduce tick-transmission of T. parva in a natural host-tick-parasite challenge model.MethodsCattle were inoculated with a multivalent antigen cocktail containing recombinant tick protective antigen subolesin as well as two additional R. appendiculatus saliva antigens: the cement protein TRP64, and three different histamine binding proteins. The cocktail also contained the T. parva sporozoite antigen p67C. The effect of vaccination on the feeding success of nymphal and adult R. appendiculatus ticks was evaluated together with the effect on transmission of T. parva using a tick challenge model.ResultsTo our knowledge, this is the first evaluation of the anti-tick effects of these antigens in the natural host-tick-parasite combination. In spite of evidence of strong immune responses to all of the antigens in the cocktail, vaccination with this combination of tick and parasite antigens did not appear to effect tick feeding success or reduce transmission of T. parva.ConclusionThe results of this study highlight the importance of early evaluation of anti-tick vaccine candidates in biologically relevant challenge systems using the natural tick-host-parasite combination.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1774-0) contains supplementary material, which is available to authorized users.

Germinal Center B Cell and T Follicular Helper Cell Responses to Viral Vector and Protein-in-Adjuvant Vaccines.

There is great interest in the development of Ab-inducing subunit vaccines targeting infections, including HIV, malaria, and Ebola. We previously reported that adenovirus vectored vaccines are potent in priming Ab responses, but uncertainty remains regarding the optimal approach for induction of humoral immune responses. In this study, using OVA as a model Ag, we assessed the magnitude of the primary and anamnestic Ag–specific IgG responses of mice to four clinically relevant vaccine formulations: replication-deficient adenovirus; modified vaccinia Ankara (a poxvirus); protein with alum; and protein in the squalene oil-in-water adjuvant Addavax. We then used flow cytometric assays capable of measuring total and Ag-specific germinal center (GC) B cell and follicular Th cell responses to compare the induction of these responses by the different formulations. We report that adenovirus vectored vaccines induce Ag insert–specific GC B cell and Ab responses of a magnitude comparable to those induced by a potent protein/squalene oil-in-water formulation whereas—despite a robust overall GC response—the insert-specific GC B cell and Ab responses induced by modified vaccinia Ankara were extremely weak. Ag-specific follicular Th cell responses to adenovirus vectored vaccines exceeded those induced by other platforms at day 7 after immunization. We found little evidence that innate immune activation by adenovirus may act as an adjuvant in such a manner that the humoral response to a recombinant protein may be enhanced by coadministering with an adenovirus lacking a transgene of interest. Overall, these studies provide further support for the use of replication-deficient adenoviruses to induce humoral responses.