Neoantigens and cancer-testis antigens as promising vaccine candidates for triple-negative breast cancer: Delivery strategies and clinical trials.

Immunotherapy is gaining prominence as a promising strategy for treating triple-negative breast cancer (TNBC). Neoantigens (neoAgs) and cancer-testis antigens (CTAs) are tumor-specific targets originating from somatic mutations and epigenetic changes in cancer cells. These antigens hold great promise for personalized cancer vaccines, as supported by preclinical and early clinical evidence in TNBC. This review delves into the potential of neoAgs and CTAs as vaccine candidates, emphasizing diverse strategies and delivery approaches. It also highlights the current status of vaccination modalities undergoing clinical trials in TNBC therapy. A comprehensive understanding of neoAgs, CTAs, vaccination strategies, and innovative delivery methods is crucial for optimizing neoAg-based immunotherapies in clinical practice.

Sustained clinical benefit of malaria chemoprevention with sulfadoxine-pyrimethamine (SP) in pregnant women in a region with high SP resistance markers.

OBJECTIVE: The effectiveness of intermittent preventive treatment of malaria in pregnancy with sulfadoxine-pyrimethamine (IPTp-SP) is threatened by increasing SP-resistance in Africa. We assessed the level of SP-resistance markers, and the clinical and parasitological effectiveness of IPTp-SP in southern Mozambique. METHODS: P. falciparum infection, antimalarial antibodies and dhfr/dhps SP-resistance mutants were detected by quantitative polymerase chain reaction (qPCR), suspension array technology and targeted deep sequencing, respectively, among 4016 HIV-negative women in Maputo province (2016-2019). Univariate and multivariate regression models were used to assess the association between taking the recommended three or more IPTp-SP doses (IPTp3+) and parasitological and clinical outcomes. RESULTS: 84.3% (3385/4016) women received three or more IPTp-SP doses. The prevalence of quintuple mutants at first antenatal care (ANC) visit was 94.2%. IPTp3+ was associated with a higher clearance rate of qPCR-detected infections from first ANC visit to delivery (adjusted odds ratio [aOR]=5.9, 95% CI: 1.5-33.3; p = 0.012), lower seroprevalence at delivery of antibodies against the pregnancy-specific antigen VAR2CSADBL34 (aOR=0.72, 95% CI: 0.54-0.95; p = 0.022), and lower prevalence of low birth weight deliveries (aOR: 0.61, 95% CI: 0.41-0.90; p = 0.013). CONCLUSION: A sustained parasitological effect of IPTp-SP contributes to the clinical effectiveness of IPTp3+ in areas with high prevalence of SP-resistance markers.

PvDBPII elicits multiple antibody-mediated mechanisms that reduce growth in a Plasmodium vivax challenge trial.

The receptor-binding domain, region II, of the Plasmodium vivax Duffy binding protein (PvDBPII) binds the Duffy antigen on the reticulocyte surface to mediate invasion. A heterologous vaccine challenge trial recently showed that a delayed dosing regimen with recombinant PvDBPII SalI variant formulated with adjuvant Matrix-MTM reduced the in vivo parasite multiplication rate (PMR) in immunized volunteers challenged with the Thai P. vivax isolate PvW1. Here, we describe extensive analysis of the polyfunctional antibody responses elicited by PvDBPII immunization and identify immune correlates for PMR reduction. A classification algorithm identified antibody features that significantly contribute to PMR reduction. These included antibody titre, receptor-binding inhibitory titre, dissociation constant of the PvDBPII-antibody interaction, complement C1q and Fc gamma receptor binding and specific IgG subclasses. These data suggest that multiple immune mechanisms elicited by PvDBPII immunization are likely to be associated with protection and the immune correlates identified could guide the development of an effective vaccine for P. vivax malaria. Importantly, all the polyfunctional antibody features that correlated with protection cross-reacted with both PvDBPII SalI and PvW1 variants, suggesting that immunization with PvDBPII should protect against diverse P. vivax isolates.

Immunogenicity of a Plasmodium vivax vaccine based on the duffy binding protein formulated using adjuvants compatible for use in humans.

The invasion of reticulocytes by Plasmodium vivax merozoites is dependent on the interaction of the Plasmodium vivax Duffy Binding Protein (PvDBP) with the Duffy antigen receptor for chemokines (DARC). The N-terminal cysteine-rich region II of PvDBP (PvDBPII), which binds DARC, is a leading P. vivax malaria vaccine candidate. Here, we have evaluated the immunogenicity of recombinant PvDBPII formulated with the adjuvants Matrix-M and GLA-SE in mice. Analysis of the antibody responses revealed comparable ELISA recognition titres as well as similar recognition of native PvDBP in P. vivax schizonts by immunofluorescence assay. Moreover, antibodies elicited by the two adjuvant formulations had similar functional properties such as avidity, isotype profile and inhibition of PvDBPII-DARC binding. Furthermore, the anti-PvDBPII antibodies were able to block the interaction of DARC with the homologous PvDBPII SalI allele as well as the heterologous PvDBPII PvW1 allele from a Thai clinical isolate that is used for controlled human malaria infections (CHMI). The cross-reactivity of these antibodies with PvW1 suggest that immunization with the PvDBPII SalI strain should neutralize reticulocyte invasion by the challenge P. vivax strain PvW1.

Detecting temporal and spatial malaria patterns from first antenatal care visits.

Pregnant women attending first antenatal care (ANC) visits represent a promising malaria surveillance target in Sub-Saharan Africa. We assessed the spatio-temporal relationship between malaria trends at ANC (n = 6471) and in children in the community (n = 3933) and at health facilities (n = 15,467) in southern Mozambique (2016-2019). ANC P. falciparum rates detected by quantitative polymerase chain reaction mirrored rates in children, regardless of gravidity and HIV status (Pearson correlation coefficient [PCC] > 0.8, χ²<1.1), with a 2-3 months lag. Only at rapid diagnostic test detection limits at moderate-to-high transmission, did multigravidae show lower rates than children (PCC = 0.61, 95%CI[-0.12-0.94]). Seroprevalence against the pregnancy-specific antigen VAR2CSA reflected declining malaria trends (PCC = 0.74, 95%CI[0.24-0.77]). 60% (9/15) of hotspots detected from health facility data (n = 6662) using a novel hotspot detector, EpiFRIenDs, were also identified with ANC data (n = 3616). Taken together, we show that ANC-based malaria surveillance offers contemporary information on temporal trends and geographic distribution of malaria burden in the community.

Anti-amyloidogenic amphipathic arginine-dehydrophenylalanine spheres capped selenium nanoparticles as potent therapeutic moieties for Alzheimer's disease.

Aggregation of both amyloid beta (Aß) peptide and hyperphosphorylated tau proteins is the major pathological hallmark of Alzheimer's disease (AD). Moieties that carry anti-amyloidogenic potency against both of the aggregating entities are considered to be promising drug candidatures for the disease. In the current work, we have synthesized amphipathic dipeptide vesicle-templated selenium nanoparticles (RΔF-SeNPs) as potential entities to combat AD. We have investigated and established their anti-amyloidogenic activity against different peptide-based amyloid models, such as the reductionist model based on the dipeptide phenylalanine-phenylalanine (FF) derived from Aß; a model based on the hexapeptide Ac-PHF6 (306VQIVYK311) derived from tau protein; and the full-length Aß42 polypeptide-based model. We also evaluated the neuroprotective characteristics of RΔF-SeNPs against FF, Ac-PHF6, and Aß42 fibril-induced toxicity in neuroblastoma, SH-SY5Y cells. RΔF-SeNPs further exhibited neuroprotective effects in streptozotocin (STZ) treated neuronal (N2a) cells carrying AD-like features. In addition, studies conducted in an intra-cerebroventricular STZ-instigated rat model of dementia revealed that RΔF-SeNP-treated animals showed improved cognitive activity and reduced Aß42 aggregate burden in brain tissues as compared with the STZ-treated group. Moreover, in vivo brain distribution studies conducted in animal models additionally demonstrated the brain-homing ability of RΔF-SeNPs. All together, these studies supported the potency of RΔF-SeNPs as efficient and propitious disease-modifying therapeutic agents for combating AD.

Vaccination with Plasmodium vivax Duffy-binding protein inhibits parasite growth during controlled human malaria infection.

There are no licensed vaccines against Plasmodium vivax. We conducted two phase 1/2a clinical trials to assess two vaccines targeting P. vivax Duffy-binding protein region II (PvDBPII). Recombinant viral vaccines using chimpanzee adenovirus 63 (ChAd63) and modified vaccinia virus Ankara (MVA) vectors as well as a protein and adjuvant formulation (PvDBPII/Matrix-M) were tested in both a standard and a delayed dosing regimen. Volunteers underwent controlled human malaria infection (CHMI) after their last vaccination, alongside unvaccinated controls. Efficacy was assessed by comparisons of parasite multiplication rates in the blood. PvDBPII/Matrix-M, given in a delayed dosing regimen, elicited the highest antibody responses and reduced the mean parasite multiplication rate after CHMI by 51% (n = 6) compared with unvaccinated controls (n = 13), whereas no other vaccine or regimen affected parasite growth. Both viral-vectored and protein vaccines were well tolerated and elicited expected, short-lived adverse events. Together, these results support further clinical evaluation of the PvDBPII/Matrix-M P. vivax vaccine.

Detecting temporal and spatial malaria patterns from first antenatal care visits.

Pregnant women attending first antenatal care (ANC) visits represent a promising malaria surveillance target in Sub-Saharan Africa. Here we assessed the spatio-temporal relationship between malaria at ANC (n=6,471), in children at the community(n=9,362) and at health facilities (n=15,467) in southern Mozambique (2016-2019). ANC P. falciparum rates detected by quantitative polymerase chain reaction mirrored rates in children, regardless of gravidity and HIV status (Pearson correlation coefficient [PCC]>0.8, χ²<1.1), with a 2-3 months lag. Only at rapid diagnostic test detection limits at moderate-to-high transmission, multigravidae showed lower rates than children (PCC=0.61, 95%CI[-0.12-0.94]). Seroprevalence against the pregnancy-specific antigen VAR2CSA reflected declining malaria trends (PCC=0.74, 95%CI[0.24-0.77]). 80% (12/15) of hotspots detected from health facility data using a novel hotspot detector, EpiFRIenDs, were also identified with ANC data. The results show that ANC-based malaria surveillance offers contemporary information on temporal trends and the geographic distribution of malaria burden in the community.

Bio-piezoelectric phenylalanine-αß-dehydrophenylalanine nanotubes as potential modalities for combinatorial electrochemotherapy in glioma cells.

Bio-piezoelectric materials are endowed with characteristic features such as non-invasiveness, small energy attenuation and deep tissue penetrability. Thus, they have the ability to serve as both diagnostic and therapeutic modalities for targeting and treating various dreaded disorders scourging mankind. Herein, piezoelectric nanotubes derived from a modified amino acid-containing dipeptide, phenylalanine-αß-dehydrophenylalanine (Phe-ΔPhe; FΔF), possessing acoustic stimulation-triggered reactive oxygen species (ROS) generating ability, were employed and projected for achieving a piezo-active response enabled anti-cancer effect in glioma cells. A model anti-cancer drug doxorubicin (Dox) was also loaded into the nanotubes and the combined system depicted enhanced ROS production and cell killing under an acoustically developed piezo-catalytic environment. Cellular level assessment studies demonstrated that the dipeptide based piezoelectric nanotubes could lead to an increase in the cellular Ca2+ ion concentration, further inducing ROS-triggered cytotoxicity accompanied by high therapeutic efficacy in C6 glioma cells. Overall, our structures have the uniqueness of serving as acoustic stimulus-driven, wireless, and non-invasive electro-chemotherapeutic agents for enabling heightened cancer cell killing and may complement other chemotherapeutic modalities for treating the disease.

Analyses of human vaccine-specific circulating and bone marrow-resident B cell populations reveal benefit of delayed vaccine booster dosing with blood-stage malaria antigens.

We have previously reported primary endpoints of a clinical trial testing two vaccine platforms for the delivery of Plasmodium vivax malaria DBPRII: viral vectors (ChAd63, MVA), and protein/adjuvant (PvDBPII with 50µg Matrix-M™ adjuvant). Delayed boosting was necessitated due to trial halts during the pandemic and provides an opportunity to investigate the impact of dosing regimens. Here, using flow cytometry - including agnostic definition of B cell populations with the clustering tool CITRUS - we report enhanced induction of DBPRII-specific plasma cell and memory B cell responses in protein/adjuvant versus viral vector vaccinees. Within protein/adjuvant groups, delayed boosting further improved B cell immunogenicity compared to a monthly boosting regimen. Consistent with this, delayed boosting also drove more durable anti-DBPRII serum IgG. In an independent vaccine clinical trial with the P. falciparum malaria RH5.1 protein/adjuvant (50µg Matrix-M™) vaccine candidate, we similarly observed enhanced circulating B cell responses in vaccinees receiving a delayed final booster. Notably, a higher frequency of vaccine-specific (putatively long-lived) plasma cells was detected in the bone marrow of these delayed boosting vaccinees by ELISPOT and correlated strongly with serum IgG. Finally, following controlled human malaria infection with P. vivax parasites in the DBPRII trial, in vivo growth inhibition was observed to correlate with DBPRII-specific B cell and serum IgG responses. In contrast, the CD4+ and CD8+ T cell responses were impacted by vaccine platform but not dosing regimen and did not correlate with in vivo growth inhibition in a challenge model. Taken together, our DBPRII and RH5 data suggest an opportunity for protein/adjuvant dosing regimen optimisation in the context of rational vaccine development against pathogens where protection is antibody-mediated.

Ultrashort Peptide-Based Hydrogel for the Healing of Critical Bone Defects in Rabbits.

The use of hydrogels as scaffolds for three-dimensional (3D) cell growth is an active area of research in tissue engineering. Herein, we report the self-assembly of an ultrashort peptide, a tetrapeptide, Asp-Leu-IIe-IIe, the shortest peptide sequence from a highly fibrillogenic protein TDP-43, into the hydrogel. The hydrogel was mechanically strong and highly stable, with storage modulus values in MPa ranges. The hydrogel supported the proliferation and successful differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) in its matrix as assessed by cell viability, calcium deposition, alkaline phosphatase (ALP) activity, and the expression of osteogenic marker gene studies. To check whether the hydrogel supports 3D growth and regeneration in in vivo conditions, a rabbit critical bone defect model was used. Micro-computed tomography (CT) and X-ray analysis demonstrated the formation of mineralized neobone in the defect areas, with significantly higher bone mineralization and relative bone densities in animals treated with the peptide hydrogel compared to nontreated and matrigel treatment groups. The ultrashort peptide-based hydrogel developed in this work holds great potential for its further development as tissue regeneration and/or engineering scaffolds.

Gravidity and malaria trends interact to modify P. falciparum densities and detectability in pregnancy: a 3-year prospective multi-site observational study.

BACKGROUND: Low-density Plasmodium falciparum infections prevail in low transmission settings, where immunity is expected to be minimal, suggesting an immune-independent effect on parasite densities. We aimed to describe parasite densities in pregnancy, and determine how gravidity and antibody-mediated immunity affect these, during a period of declining malaria transmission in southern Mozambique. METHODS: We documented P. falciparum infections at first antenatal care visits (n = 6471) between November 2016 and October 2019 in Ilha Josina (high-to-moderate transmission area), Manhiça (low transmission area), and Magude (pre-elimination area). Two-way interactions in mixed-effects regression models were used to assess gravidity-dependent differences in quantitative PCR-determined P. falciparum positivity rates (PfPRqPCR) and densities, in the relative proportion of detectable infections (pDi) with current diagnostic tests (≥ 100 parasites/µL) and in antimalarial antibodies. RESULTS: PfPRqPCR declined from 28 to 13% in Ilha Josina and from 5-7 to 2% in Magude and Manhiça. In primigravidae, pDi was highest in Ilha Josina at the first study year (p = 0.048), which declined with falling PfPRqPCR (relative change/year: 0.41, 95% CI [0.08; 0.73], p = 0.029), with no differences in antibody levels. Higher parasite densities in primigravidae from Ilha Josina during the first year were accompanied by a larger reduction of maternal hemoglobin levels (- 1.60, 95% CI [- 2.49; - 0.72; p < 0.001), than in Magude (- 0.76, 95% CI [- 1.51; - 0.01]; p = 0.047) and Manhiça (- 0.44, 95% CI [- 0.99; 0.10; p = 0.112). In contrast, multigravidae during the transmission peak in Ilha Josina carried the lowest pDi (p = 0.049). As PfPRqPCR declined, geometric mean of parasite densities increased (4.63, 95% CI [1.28; 16.82], p = 0.020), and antibody levels declined among secundigravidae from Ilha Josina. CONCLUSIONS: The proportion of detectable and clinically relevant infections is the highest in primigravid women from high-to-moderate transmission settings and decreases with declining malaria. In contrast, the falling malaria trends are accompanied by increased parasite densities and reduced humoral immunity among secundigravidae. Factors other than acquired immunity thus emerge as potentially important for producing less detectable infections among primigravidae during marked declines in malaria transmission.

Process development and preclinical evaluation of a major Plasmodium falciparum blood stage vaccine candidate, Cysteine-Rich Protective Antigen (CyRPA).

Plasmodium falciparum Cysteine-Rich Protective Antigen (CyRPA) is an essential, highly conserved merozoite antigen that forms an important multi-protein complex (RH5/Ripr/CyRPA) necessary for erythrocyte invasion. CyRPA is a promising blood-stage vaccine target that has been shown to elicit potent strain-transcending parasite neutralizing antibodies. Recently, we demonstrated that naturally acquired immune anti-CyRPA antibodies are invasion-inhibitory and therefore a correlate of protection against malaria. Here, we describe a process for the large-scale production of tag-free CyRPA vaccine in E. coli and demonstrate its parasite neutralizing efficacy with commonly used adjuvants. CyRPA was purified from inclusion bodies using a one-step purification method with high purity (>90%). Biochemical and biophysical characterization showed that the purified tag-free CyRPA interacted with RH5, readily detected by a conformation-specific CyRPA monoclonal antibody and recognized by sera from malaria infected individuals thus indicating that the recombinant antigen was correctly folded and retained its native conformation. Tag-free CyRPA formulated with Freund's adjuvant elicited highly potent parasite neutralizing antibodies achieving inhibition of >90% across diverse parasite strains. Importantly, we identified tag-free CyRPA/Alhydrogel formulation as most effective in inducing a highly immunogenic antibody response that exhibited efficacious, cross-strain in vitro parasite neutralization achieving ~80% at 10 mg/ml. Further, CyRPA/Alhydrogel vaccine induced anti-parasite cytokine response in mice. In summary, our study provides a simple, scalable, cost-effective process for the production of tag-free CyRPA that in combination with human-compatible adjuvant induces efficacious humoral and cell-mediated immune response.

Conformationally Restricted Dipeptide-Based Nanoparticles for Delivery of siRNA in Experimental Liver Cirrhosis.

Liver cirrhosis is a major health problem with multiple associated complications. The presently available drug delivery systems showed moderate site-specific delivery of antifibrotic molecules to the diseased liver; therefore, research on more effective and selective delivery systems in the context of liver cirrhosis remains a necessity in clinical investigation. The aim of the present study was to develop a peptide-based targeted nanocarrier to deliver an oligonucleotide to the hepatic sinusoidal and perivascular regions of the cirrhotic liver. We have synthesized and characterized a conformationally restricted targeted pentapeptide (RΔFRGD), which contains an unnatural amino acid, α,ß-dehydrophenylalanine (ΔF). The RΔFRGD self-assembled into spherical nanoparticles (NPs) and was characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Next, we investigated the delivery potential of the pentapeptide-based NPs to make a stable complex with a well-established small interference RNA and studied its site-specific delivery in experimental liver cirrhosis. We used siNR4A1 of the orphan nuclear receptor 4A1 (NR4A1), a well-known regulatory checkpoint for controlling liver fibrosis. Peptide NPs and their complex with siNR4A1 showed high biocompatibility against various mammalian cell lines. Hepatic tissue biodistribution analysis illustrated that targeted NPs predominantly accumulated in the cirrhotic liver compared to normal rats, specifically in sinusoidal and perivascular areas. A significant downregulation of the NR4A1 mRNA expression (-70%) andlower levels of the NR4A1/GAPDH ratio (-55%) were observed in the RΔFRGD-siNR4A1 nanocomplex-treated group in comparison to the RΔFRGD-vehicle group (RΔFRGD-Veh) at the gene and protein levels, respectively. In addition, in vivo inhibition of NR4A1 produced a significant aggravation in hepatic fibrosis compared with siRNA-vehicle-treated rats (+41% in the MT stain). The novel pentapeptide-based targeted delivery system can be further evaluated and validated for therapeutic purposes in various pathological conditions.

Chemically Modified Dipeptide Based Hydrogel Supports Three-Dimensional Growth and Functions of Primary Hepatocytes.

A huge shortage of organ donors, particularly in the case of liver, has necessitated the development of alternative therapeutic strategies. Primary hepatocytes (pHCs) transplantation has made a considerable transition from bench to bedside, but the short-term viability and functionality of pHCs in in vitro limit their use for clinical applications. Different cell culture strategies are required to maintain the proliferation of pHCs for extended periods. Here, we described the formation of a hybrid scaffold based on a modified dipeptide for the culture of pHCs. First, the dipeptide (Dp), isoleucine-α,ß-dehydrophenylalanine (IΔF) was synthesized, purified, and fully characterized. IΔF readily formed a highly stable hydrogel, which was also characterized by CD, TEM, and thioflavin T assay. The addition of soluble liver extracellular matrix (sLEM) to the dipeptide readily formed a hybrid scaffold that was characterized by TEM, and its mechanical strength was determined by rheology experiments. The hybrid scaffold was translucent, biocompatible, and proteolytically stable and, with its mechanical strength, closely mimicked that of the native liver. LEM1-Dp matrix exhibited high biocompatibility in the readily available adherent liver cell line Huh7 and primary rat hepatocyte cells (pHCs). pHCs cultured on LEM1-Dp matrix also maintained significantly higher cell viability and an escalated expression of markers related to the hepatocytes such as albumin as compared to that observed in cells cultured on collagen type I (Col I)-coated substrate plate (col-TCTP). Z-stacking of confocal laser microscopy's volume view clearly indicated pHCs seeded on top of the hydrogel matrix migrated toward the Z direction showing 3D growth. Our results indicated that low molecular weight dipeptide hydrogel along with sLEM can resemble biomimetic 3D-like microenvironments for improved pHCs proliferation, differentiation, and function. This hybrid scaffold is also easy to scale up, which makes it suitable for several downstream applications of hepatocytes, including drug development, pHCs transplantation, and liver regeneration.

Impact of a blood-stage vaccine on Plasmodium vivax malaria.

Background: There are no licensed vaccines against Plasmodium vivax , the most common cause of malaria outside of Africa. Methods: We conducted two Phase I/IIa clinical trials to assess the safety, immunogenicity and efficacy of two vaccines targeting region II of P. vivax Duffy-binding protein (PvDBPII). Recombinant viral vaccines (using ChAd63 and MVA vectors) were administered at 0, 2 months or in a delayed dosing regimen (0, 17, 19 months), whilst a protein/adjuvant formulation (PvDBPII/Matrix-M™) was administered monthly (0, 1, 2 months) or in a delayed dosing regimen (0, 1, 14 months). Delayed regimens were due to trial halts during the COVID-19 pandemic. Volunteers underwent heterologous controlled human malaria infection (CHMI) with blood-stage P. vivax parasites at 2-4 weeks following their last vaccination, alongside unvaccinated controls. Efficacy was assessed by comparison of parasite multiplication rate (PMR) in blood post-CHMI, modelled from parasitemia measured by quantitative polymerase-chain-reaction (qPCR). Results: Thirty-two volunteers were enrolled and vaccinated (n=16 for each vaccine). No safety concerns were identified. PvDBPII/Matrix-M™, given in the delayed dosing regimen, elicited the highest antibody responses and reduced the mean PMR following CHMI by 51% (range 36-66%; n=6) compared to unvaccinated controls (n=13). No other vaccine or regimen impacted parasite growth. In vivo growth inhibition of blood-stage P. vivax correlated with functional antibody readouts of vaccine immunogenicity. Conclusions: Vaccination of malaria-naïve adults with a delayed booster regimen of PvDBPII/ Matrix-M™ significantly reduces the growth of blood-stage P. vivax . Funded by the European Commission and Wellcome Trust; VAC069, VAC071 and VAC079 ClinicalTrials.gov numbers NCT03797989 , NCT04009096 and NCT04201431 .

Evaluation of antibody serology to determine current helminth and Plasmodium falciparum infections in a co-endemic area in Southern Mozambique.

BACKGROUND: Soil-transmitted helminths (STH), Schistosoma spp. and Plasmodium falciparum are parasites of major public health importance and co-endemic in many sub-Saharan African countries. Management of these infections requires detection and treatment of infected people and evaluation of large-scale measures implemented. Diagnostic tools are available but their low sensitivity, especially for low intensity helminth infections, leaves room for improvement. Antibody serology could be a useful approach thanks to its potential to detect both current infection and past exposure. METHODOLOGY: We evaluated total IgE responses and specific-IgG levels to 9 antigens from STH, 2 from Schistosoma spp., and 16 from P. falciparum, as potential markers of current infection in a population of children and adults from Southern Mozambique (N = 715). Antibody responses were measured by quantitative suspension array Luminex technology and their performance was evaluated by ROC curve analysis using microscopic and molecular detection of infections as reference. PRINCIPAL FINDINGS: IgG against the combination of EXP1, AMA1 and MSP2 (P. falciparum) in children and NIE (Strongyloides stercoralis) in adults and children had the highest accuracies (AUC = 0.942 and AUC = 0.872, respectively) as markers of current infection. IgG against the combination of MEA and Sm25 (Schistosoma spp.) were also reliable markers of current infection (AUC = 0.779). In addition, IgG seropositivity against 20 out of the 27 antigens in the panel differentiated the seropositive endemic population from the non-endemic population, suggesting a possible role as markers of exposure although sensitivity could not be assessed. CONCLUSIONS: We provided evidence for the utility of antibody serology to detect current infection with parasites causing tropical diseases in endemic populations. In addition, most of the markers have potential good specificity as markers of exposure. We also showed the feasibility of measuring antibody serology with a platform that allows the integration of control and elimination programs for different pathogens.

Plasmodium falciparum Cysteine-Rich Protective Antigen (CyRPA) Elicits Detectable Levels of Invasion-Inhibitory Antibodies during Natural Infection in Humans.

Plasmodium falciparum cysteine-rich protective antigen (CyRPA) is a conserved component of an essential erythrocyte invasion complex (RH5/Ripr/CyRPA) and a target of potent cross-strain parasite-neutralizing antibodies. While naturally acquired human RH5 antibodies have been functionally characterized, there are no similar reports on CyRPA. Thus, we analyzed the parasite-neutralizing activity of naturally acquired human CyRPA antibodies. In this regard, CyRPA human antibodies were measured and purified from malaria-infected plasma obtained from patients in central India and analyzed for their parasite neutralizing activity via in vitro growth inhibition assays (GIA). We report that, despite being susceptible to antibodies, CyRPA is a highly conserved antigen that does not appear to be under substantial immune selection pressure, as a very low acquisition rate for anti-CyRPA antibodies was reported in malaria-exposed Indians. We demonstrate for the first time that the small amounts of natural CyRPA antibodies exhibited functional parasite-neutralizing activity and that a CyRPA-based vaccine formulation induces highly potent antibodies in rabbits. Importantly, the vaccine-induced CyRPA antibodies exhibited a robust 50% inhibitory concentration (IC50) of 21.96 µg/ml, which is comparable to the IC50 of antibodies against the leading blood-stage vaccine candidate, reticulocyte-binding-like homologous protein 5 (RH5). Our data support CyRPA as a unique vaccine target that is highly susceptible to immune attack but is highly conserved compared to other leading candidates such as MSP-1 and AMA-1, further substantiating its promise as a leading blood-stage vaccine candidate.

Conformationally restricted, dipeptide-based, self-assembled nanoparticles for efficient vancomycin delivery.

Aim: Emergence of vancomycin (Van) resistance, and usage of its higher dose and short half-life are posing a serious concern. Slow and sustained release of Van using a nanodelivery system may overcome these problems. Materials & methods: Arginine-α,ß-dehydrophenylalanine (RΔF) was synthesized using solution-phase synthesis which self-assembled into nanospheres. Van was entrapped in the nanoparticles (NPs). In vitro and in vivo efficacy of Van-RΔF was determined using broth microdilution and the mouse thigh infection model, respectively. Results & conclusion: Van-RΔF NPs efficiently inhibited bacterial growth (Staphylococcus aureus), while Van alone showed limited growth inhibition in in vitro. Intravenous administration of Van-RΔF in mice with bacterial thigh infection showed enhanced efficacy (double) compared with Van alone, which indicates its high potential for further development.

Currently, microbial infections have become the most prevalent threat to human health. In the past few decades, researchers have tried different strategies to deal with these infections by developing new antimicrobial agents and/or improving the efficacy of already available antimicrobial agents. Controlled delivery of antimicrobial agents using nanosized vehicle systems has shown great promise in antimicrobial therapy. The authors have developed an ultrashort, modified, peptide-based nanoparticle system that can load vancomycin and release it in a controlled and sustained manner. Unlike other polymer-based nanoparticles, these dipeptide-based nanoparticles are easy to synthesize and highly biocompatible in nature. Vancomycin delivered via these peptide-based nanoparticles showed higher antibacterial activity than the drug alone. These results clearly indicated the high potential of this nanoformulation for further development as a delivery vehicle system for efficient antimicrobial therapy.