An MPER antibody neutralizes HIV-1 using germline features shared among donors.

The membrane-proximal external region (MPER) of HIV-1 envelope glycoprotein (Env) can be targeted by neutralizing antibodies of exceptional breadth. MPER antibodies usually have long, hydrophobic CDRH3s, lack activity as inferred germline precursors, are often from the minor IgG3 subclass, and some are polyreactive, such as 4E10. Here we describe an MPER broadly neutralizing antibody from the major IgG1 subclass, PGZL1, which shares germline V/D-region genes with 4E10, has a shorter CDRH3, and is less polyreactive. A recombinant sublineage variant pan-neutralizes a 130-isolate panel at 1.4 μg/ml (IC50). Notably, a germline revertant with mature CDR3s neutralizes 12% of viruses and still binds MPER after DJ reversion. Crystal structures of lipid-bound PGZL1 variants and cryo-EM reconstruction of an Env-PGZL1 complex reveal how these antibodies recognize MPER and viral membrane. Discovery of common genetic and structural elements among MPER antibodies from different patients suggests that such antibodies could be elicited using carefully designed immunogens

Nanoparticle size influences the magnitude and quality of mucosal immune responses after intranasal immunization

Background: The development of nanoparticulate antigen-delivery systems is an important emerging area of vaccinology, being sought to amplify immune responses to recombinant antigens that are poorly immunogenic. Nanoparticle size may play an important role in influencing the activity of such particulate-based adjuvants. Methods: To explore how the size of nanoparticles that are in the range of many common viruses can modulate the magnitude and quality of mucosal immune responses, the model antigen ovalbumin (OVA) was conjugated to 30 nm or 200 nm polypropylene sulfide nanoparticles (NPs) and administered intranasally to C57BL/6 mice. Results: We show that by increasing the size of the NPs from 30 to 200 nm, OVA was more effectively delivered into both MHC class I and MHC class II-presentation pathways. Intranasal immunization with the 200 nm NPs increased the magnitude of CD4(+) T cell responses in the lungs, as well as systemic and mucosal humoral responses. Most importantly, 200 nm NPs increased the proportion of antigen-specific polyfunctional CD4(+) T cells as compared to 30 nm NPs. Conclusions: The 200 nm NPs are a very interesting antigen nanocarrier for prophylactic vaccines against mucosal pathogens that require multifunctional CD4(+) T cells for protection. These results contribute to our understanding of how the size of an antigen-conjugated nanoparticle modulates mucosal immune responses to a protein antigen and may be useful to engineer subunit vaccines able to elicit appropriate mucosal immune responses that correlate with protection. (C) 2012 Elsevier Ltd. All rights reserved

A high-throughput nanoimmunoassay chip applied to large-scale vaccine adjuvant screening

Large-scale experimentation is becoming instrumental in enabling new discoveries in systems biology and personalized medicine. We developed a multiplexed high-throughput nanoimmunoassay chip capable of quantifying four biomarkers in 384 5 nL samples, for a total of 1536 assays. Our platform, compared to conventional methods, reduces volume and reagent cost by similar to 1000-fold. We applied our platform in the context of systems vaccinology, to assess the synergistic production of inflammatory cytokines from dendritic cells (DCs) stimulated with 10 different adjuvants that target members of the Toll-like receptor (TLR) family. We quantified these adjuvants both alone and in all pairwise combinations, for a total of 435 conditions, revealing numerous synergistic pairs. We evaluated two synergistic interactions, MPLA + Gardiquimod and MPLA + CpG-B, in a mouse model, where we measured the same inflammatory cytokines in bronchoalveolar lavage and in blood serum at 4 different time points using our chip, and observed similar synergistic effects in vivo, demonstrating the potential of our microfluidic platform to predict agonistic immunogenicity. More generally, a high-throughput, matrix-insensitive, low sample volume technology can play an important role in the discovery of novel therapeutics and research areas requiring large-scale biomarker quantitation

Tunable T cell immunity towards a protein antigen using polymersomes vs. solid-core nanoparticles

Using poly(propylene sulfide) (PPS) and poly(ethylene glycol) (PEG) as components of a nanocarrier platform, we sought to compare immune responses induced by PPS-bl-PEG polymersomes (PSs; watery-core structures, with antigen incorporated within the PSs) and PEG-stabilized PPS nanopartides (NPs; solid-core structures, with antigen conjugated upon the NP surface). We have previously shown strong CD8(+) T cell responses to antigen conjugated to NPs via a disulfide link, and here we investigated the extent to which antigen incorporated within oxidatively-sensitive PSs could induce CD4(+) or CD8(+) T cell responses. C57BL/6 mice were subcutaneously immunized with free ovalbumin (OVA) as a model antigen, or equivalent doses of OVA-loaded into PSs, conjugated onto NPs, or given as a mixture of the two. Free CpG was used as an adjuvant. Antigen-loaded PSs induced enhanced frequencies of antigen-specific CD4(+) T cells in the spleen, lymph nodes and lungs as compared to the NP formulation, whereas antigen-conjugated NPs induced stronger CD8(+) T cell responses. Co-administration of both PSs and NPs elicited T cell immunity characteristic of the two nanocarriers at the same time, i.e. both strong CD4(+) and CD8(+) T cell responses. These results have important implications for particulate-based vaccine design and highlight the potential of using different antigen-delivery systems for the induction of both T helper and cytotoxic T lymphocyte immune responses. (C) 2013 Elsevier Ltd. All rights reserved

Study of the genotypic resistant pattern in HIV-infected women and children from rural west Cameroon

The distribution of antiretroviral (ARV) therapy resistance mutations among HIV-1 strains was evaluated in 39 postpartum women, one pregnant woman, and 12 HIV-positive babies (seven newborns and five children) living in rural west Cameroon. Thirty-five women and all newborns received a single dose of nevirapine (NVP) to prevent mother-to-child transmission of HIV-1; two women were ARV treated and three were ARV naive. Of the 52 viral strains examined, three were subtype B, 45 were classified into eight HIV-1 non-B subtypes, and four remained unclassifiable. Sequence analysis for genotypic drug resistance in the reverse transcriptase (RT) gene showed the presence of mutations associated with nonnucleoside RT inhibitor resistance in 20% of the samples from NVP-treated women and in 57% of those from treated newborns. Mutations associated with nucleoside RT inhibitors (M184V in one case and V118I in four cases) were found in five samples, despite being derived from ARV-naive patients. As expected, a greater frequency of mutations was found in the protease gene region. Of the sequences analyzed, 79% harbored five to seven specific mutations. The secondary mutations showed the typical protease inhibitor resistance-associated pattern for non-subtype B viruses, M36I being the predominant mutation (92.5% in women, 100% in babies). Other mutations frequently detected were K20I, L63P, H69K, and I13V. These findings confirm that resistance mutations can be detected in ARV-naive patients infected with non-B subtypes and emphasize an urgent need for studies assessing the impact of these mutations on the efficacy of subsequent ARV therapy and on the appearance of drug-resistant strains

Dendritic cell activation and T cell priming with adjuvant- and antigen-loaded oxidation-sensitive polymersomes

While current subunit vaccines successfully induce humoral immune responses, a need exists for vaccine strategies to elicit strong cell-mediated immunity to address diseases such as cancer and chronic viral infection. Polymersomes are stable vesicles composed of self-assembling block copolymers with tunable degradation properties allowing delivery of both hydrophilic (within vesicle interior) or hydrophobic (within vesicle membrane) payload molecules. Here we apply oxidation-sensitive nanoscale polymersomes for both antigen and adjuvant delivery to dendritic cell (DC) endosomes. Calcein-loaded polymersomes were observed to release their payload initially in multiple DC endosomal compartments and subsequently within the cytosol. With either the Toll-like receptor agonists gardiquimod or R848 as payloads within the polymersomes, release resulted in DC activation, as indicated by induction of inflammatory cytokine expression and upregulation of DC maturation surface markers: for example, the ability of gardiquimod to induce IL-6 and IL-12 cytokine expression by DCs was enhanced 10-fold when loaded within polymersomes. With the model antigen ovalbumin as a payload, release resulted in CD8(+) T cell cross-priming by promoting protein antigen cross-presentation through MHC I, as indicated by activation of OT-I CD8(+) T cells. Our results demonstrate that oxidation-sensitive polymersomes can function as a vaccine delivery platform for inducing cell-mediated antigen-specific immune responses. (C) 2012 Elsevier Ltd. All rights reserved

High-Density Array of Well-Ordered HIV-1 Spikes on Synthetic Liposomal Nanoparticles Efficiently Activate B Cells

A major step toward an HIV-1 vaccine is an immunogen capable of inducing neutralizing antibodies. Envelope glycoprotein (Env) mimetics, such as the NFL and SOSIP designs, generate native-like, well-ordered trimers and elicit tier 2 homologous neutralization (SOSIPs). We reasoned that the display of well-ordered trimers by high-density, particulate array would increase B cell activation compared to soluble trimers. Here, we present the design of liposomal nanoparticles displaying well-ordered Env spike trimers on their surface. Biophysical analysis, cryo- and negative stain electron microscopy, as well as binding analysis with a panel of broadly neutralizing antibodies confirm a high-density, well-ordered trimer particulate array. The Env-trimer-conjugated liposomes were superior to soluble trimers in activating B cells ex vivo and germinal center B cells in vivo. In addition, the trimer-conjugated liposomes elicited modest tier 2 homologous neutralizing antibodies. The trimer-conjugated liposomes represent a promising initial lead toward the development of more effective HIV vaccine immunogens

PPS nanoparticles as versatile delivery system to induce systemic and broad mucosal immunity after intranasal administration

Degradable polymer nanoparticles (NPs, 50nm) based on polypropylene sulfide (PPS) were conjugated to thiolated antigen and adjuvant proteins by reversible disulfide bonds and evaluated in mucosal vaccination. Ovalbumin was used as a model antigen, and antigen-conjugated NPs were administered intranasally in the mouse. We show penetration of nasal mucosae, transit via M cells, and uptake by antigen-presenting cells in the nasal-associated lymphoid tissue. Ovalbumin-conjugated NPs induced cytotoxic T lymphocytic responses in lung and spleen tissues, as well as humoral response in mucosal airways. Co-conjugation of the TLR5 ligand flagellin further enhanced humoral responses in the airways as well as in the distant vaginal and rectal mucosal compartments and induced cellular immune responses with a Th1 bias, in contrast with free flagellin. The PPS NP platform thus appears interesting as a platform for intranasally-administered mucosal vaccination for inducing broad mucosal immunity

Travellers' Risk Behaviors and Health Problems: Post-Travel Follow Up in Two Travel Medicine Centers in Italy

OBJECTIVES: We examined the association between travellers' characteristics, compliance with pre-travel recommendations and health problems.METHODS: Volunteer travellers were enrolled and data collected using a questionnaire between 30-60 days after returning home. We analyzed the associations through bivariate and multivariate models.RESULTS: Of the 468 enrolled travelers, 68% consumed raw food and 81% food containing milk and/or eggs. 32% consumed street vendor food and 30% drinks containing ice. 24% used the recommended mechanical prophylaxis measures. 46% got sick during and/or after travel (gastrointestinal symptoms most frequently). Factors predisposing to health problems were female gender, youth/middle age, intermediate travel duration and profession. The American continent and staying in hostels and tents were significantly associated with febrile illness. Street vendor food was significantly associated with skin reactions.CONCLUSIONS: Adherence to behavioral recommendations remains low. Travellers must be informed of health risks during and after travel

Genotypic resistance of archived and circulating viral strains in the blood of treated HIV-infected individuals

The aim of this study was to evaluate patterns of antiretroviral resistance of HIV-1 in peripheral blood mononuclear cells (PBMCs) and in the plasma of patients whose therapeutic regimen is failing. Plasma and PBMC samples were collected from 95 HIV-infected patients undergoing long-term treatment. Genotyping of the reverse transcriptase (RT) and protease genes of HIV-1 was undertaken using the fluorescent dideoxy-terminator method. Comparison of the amino acid sequence of the RT and protease genes in cell-associated variants of HIV-1 with that of the plasma revealed that 62 of the 95 patients' samples tested exhibited different genotypic resistance patterns (discordant samples [DSs]). In 27% of samples, the patterns of resistance detected were concordant in both compartments. In 51% of DSs, the greatest number of mutations was found in plasma; however, in 37% of DSs, greater numbers of mutations were found in PBMC DNA. The HIV mutation patterns detected in plasma do not necessarily reflect those found in the cell-associated compartment. The observation that the cellular compartment may contain an archive of the resistance variant makes this reservoir an interesting substrate for analysis of the "resistance potential" in a given patient