A comparative study of natural immune responses against Plasmodium vivax C-terminal merozoite surface protein-1 (PvMSP-1) and apical membrane antigen-1 (PvAMA-1) in two endemic settings

The mechanisms of cellular and humoral immune responses against P. vivax parasite remain poorly understood. Several malaria immunological studies have been conducted in endemic regions where both P. falciparum and P. vivax parasites co-exist. In this study, a comparative analysis of immunity to Plasmodium vivax antigens in different geography and incidence of Plasmodium spp. infection was performed. We characterised antibodies against two P. vivax antigens, PvMSP-1 and PvAMA-1, and the cross-reactivity between these antigens using plasma from acute malaria infected patients living in the central region of China and in the western border of Thailand. P. vivax endemicity is found in central China whereas both P. vivax and P. falciparum are endemic in Thailand. There was an increased level of anti-PvMSP-1/anti-PvAMA-1 in both populations. An elevated level of antibodies to total P. vivax proteins and low level of antibodies to total P. falciparum proteins was found in acute P. vivax infected Chinese, suggesting antibody cross-reactivity between the two species. P. vivax infected Thai patients had both anti-P. vivax and anti-P. falciparum antibodies as expected since both species are present in Thailand. More information on humoral and cell mediated immunity during acute P. vivax-infection in the area where only single P. vivax species existed is of great interest in the relation of building up anti-disease severity caused by P. falciparum. This knowledge will support vaccine development in the future

Hybrid Fluorescent-Magnetic Polymeric Particles for Biomedical Applications

International audienc

Detection of Vibrio cholerae Using the Intrinsic Catalytic Activity of a Magnetic Polymeric Nanoparticle

A novel and sensitive magnetic polymeric nanoparticle (MPNP)–polymerase chain reaction–colorimetry (magneto–PCR–colorimetry) technique was developed for detection of Vibrio cholerae (V. cholerae). The technique involved an amplification of V. cholerae DNA on the surface of an MPNP and then employed the intrinsic catalytic activity of the MPNP to detect the target gene by colorimetry. An amino-modified forward primer was covalently labeled onto the MPNP surface which would bind to PCR product during PCR cycling. By employing the catalytic activity of the MPNP, the analysis of PCR product bound MPNP yielded a sensitivity of 10³ CFU/mL of V. cholerae in buffer system within 4 h. The specificity and efficiency of the technique were investigated by using various bacterial DNAs in drinking and tap water

Solvent-sensitive nanoparticle-enhanced PCR assay for the detection of enterotoxigenic Escherichia coli

Abstract Stimulus-responsive nanoparticles are among the most utilized nanoscale materials in biomedical applications. As these nanoparticles exhibit a manipulable response to a particular stimulus, such as pH, heat, and organic solvent, they are potential signalling units in diagnostic assays. This study aims to enhance the limit of detection and reduce the turnaround time of magnetic nanoparticle polymerase chain reaction (PCR) enzyme-linked gene assay (MELGA), an advanced PCR-based technique termed the solvent-sensitive nanoparticle (SSNP)-enhanced PCR assay. This technique was proposed to detect pathogenic enterotoxigenic Escherichia coli (ETEC) through applying stimulus-responsive nanoparticles. The SSNPs were elaborated with three main components, including mesoporous silica nanoparticles as a structural unit, organic dye (Nile red) as a payload, and the corresponding organic solvent-sensitive polymer shell as “gatekeeper” (poly(maleic anhydride-alt-methyl vinyl ether, PMAMVE). A suitable organic solvent capable of inducing polymer swelling and dye dissolution was investigated by considering a solubility parameter. Using ethanol, the encapsulated Nile red can diffuse out of the SSNPs faster than other solvents and reach a constant concentration within 15 min. For the PCR inhibition study, various SSNPs concentrations (10–30 μg/reaction) were mixed with the ETEC gene and PCR reagent. The results showed that the particles in this concentration range did not inhibit PCR. By comparing the efficacy of conventional PCR, MELGA, and SSNP-enhanced PCR assay, the proposed technique showed a better detection limit than that of PCR, whereas that of MELGA was the lowest. Moreover, compared to MELGA or conventional PCR, this technique provided remarkably faster results in the postamplification process

Combination of PCR and dual nanoparticles for detection of Plasmodium falciparum

We thank Dr. Chanin Nantasenamat for linguistic advice. We also thank Miss Siriruk Changrob and Miss Jitrada Wongpreecha for graphical artworks.International audienceHighly reactive particle-based DNA amplification was developed for the detection of the Pfg377 gene from P. falciparum gametocytes using functional magnetic latex particles (MLPs) and quantum dots encapsulated polymer particles (QDs-PPs). Firstly, MLPs were prepared from the precipitation of iron oxide, polymerization using initiator, and adsorption of aminodextran (AMD) so as to provide amino-functionalized MLPs. Furthermore, amino-containing polymer particles (PPs) were prepared by emulsifier-free polymerization and encapsulated with fluorescent quantum dots (QDs) for use as a signaling support. Subsequently, poly(maleic anhydride-alt-methyl vinyl ether) (PMAMVE) copolymer was effectively used for rapid and simple grafting of amino-modified DNA primers onto the surface of amino-functionalized particles thereby providing a promising method for particle immobilization. Herein, primer-grafted particles were applied in the amplification of the Pfg377 gene using the PCR approach. After amplification, PCR products containing PMAMVE-grafted MLPs and QDs-PPs were separated using a magnet and examined via a fluorescence microscope. PMAMVE-grafted particles were not found to inhibit the PCR reaction while facilitating efficient fluorescent detection of the PCR product. Results showed high sensitivity and specificity for the detection of amplified Pfg377 gene within only a few steps. This procedure represents a novel improvement to the post-amplification analysis

A model of modified meta -iodobenzylguanidine conjugated gold nanoparticles for neuroblastoma treatment

International audience127 I-modified m IBG was successfully synthesized and grafted covalently to the surface of carboxylated PEG-GNPs. The particles were not toxic to the normal fibroblast cells while specifically internalized into neuroblastoma cells line via NET

Development of loop-mediated isothermal amplification (LAMP) assay using SYBR safe and gold-nanoparticle probe for detection of Leishmania in HIV patients

Abstract Asymptomatic leishmaniasis cases have continuously increased, especially among patients with HIV who are at risk to develop further symptoms of cutaneous and visceral leishmaniasis. Thus, early diagnosis using a simple, sensitive and reliable diagnostic assay is important because populations at risk mostly reside in rural communities where laboratory equipment is limited. In this study, the highly sensitive and selective determination of Leishmania infection in asymptomatic HIV patients was achieved using dual indicators (SYBR safe and gold-nanoparticle probe; AuNP-probe) in one-step LAMP method based on basic instruments. The assay can be simply evaluated under the naked eye due to clear interpretation of fluorescent emission of LAMP-SYBR safe dye-complex and colorimetric precipitate of specific AuNP-probes. The sensitivities and specificities of fluorescent SYBR safe dye and AuNP-probe indicators were equal, which were as high as 94.1 and 97.1%, respectively. Additionally, detection limits were 102 parasites/mL (0.0147 ng/µL), ten times more sensitivity than other related studies. To empower leishmaniasis surveillance, this inexpensive one-step SYBR safe and AuNP-LAMP assay is reliably fast and simple for field diagnostics to point-of-care settings, which can be set up in all levels of health care facilities including resource limited areas, especially in low to middle income countries

Immunity to Malaria in <em>Plasmodium vivax</em> Infection: A Study in Central China

<div><h3>Background</h3><p><em>P. vivax</em> infection is characterised by relapsing fever, indicating reinfection by previously hidden parasites in the host. Relapsed infection can lead to the activation of the memory T cell pool, which may lead to protective immunity. This study aims to characterise immune responses in acute <em>P. vivax</em>-infected patients living in an area of central China characterised by only <em>P. vivax</em> infection.</p> <h3>Methodology/Principal Findings</h3><p>We conducted a cross-sectional immune-phenotypic analysis of adults using the following inclusion criteria: acute <em>P. vivax</em> infection (N = 37), a history of <em>P. vivax</em> infection (N = 17), and no known history of <em>P. vivax</em> infection (N = 21). We also conducted a 2-week longitudinal analysis following acute <em>P. vivax</em> infection, in which PBMC proliferation was measured in response to <em>P. vivax</em> and <em>P. falciparum</em> blood stage lysates. Using flow cytometry, we showed elevated memory T cells in the blood during acute <em>P. vivax</em> infection. The levels of γδ T cells were two-fold higher than those measured in naive controls. This result suggested that in the two populations, memory and γδ T cells promptly responded to <em>P. vivax</em> parasites. Interestingly, <em>P. falciparum</em> antigens stimulated T cells obtained from <em>P. vivax</em>-infected patients during a day 14-convalescence, whereas lymphocytes from the naïve control group responded to a lower degree of convalescence.</p> <h3>Conclusions/Significance</h3><p>Cell-mediated immunity during the convalescent period of the <em>P. vivax</em>-infected hosts was comprised of T cells that were specifically able to recognise <em>P. falciparum</em> antigens. Although the magnitude of the response was only half that measured after stimulation with <em>P. vivax</em> antigens, the matter of cross-antigenic stimulation is of great interest.</p> </div