Molecular determinants of cross-reactivity and potency by VH3-33 antibodies against the Plasmodium falciparum circumsporozoite protein.

IGHV3-33-encoded antibodies are prevalent in the human humoral response against the Plasmodium falciparum circumsporozoite protein (PfCSP). Among VH3-33 antibodies, cross-reactivity between PfCSP major repeat (NANP), minor (NVDP), and junctional (NPDP) motifs is associated with high affinity and potent parasite inhibition. However, the molecular basis of antibody cross-reactivity and the relationship with efficacy remain unresolved. Here, we perform an extensive structure-function characterization of 12 VH3-33 anti-PfCSP monoclonal antibodies (mAbs) with varying degrees of cross-reactivity induced by immunization of mice expressing a human immunoglobulin gene repertoire. We identify residues in the antibody paratope that mediate cross-reactive binding and delineate four distinct epitope conformations induced by antibody binding, with one consistently associated with high protective efficacy and another that confers comparably potent inhibition of parasite liver invasion. Our data show a link between molecular features of cross-reactive VH3-33 mAb binding to PfCSP and mAb potency, relevant for the development of antibody-based interventions against malaria.

A multi-specific, multi-affinity antibody platform neutralizes sarbecoviruses and confers protection against SARS-CoV-2 in vivo.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), has been responsible for a global pandemic. Monoclonal antibodies (mAbs) have been used as antiviral therapeutics; however, these therapeutics have been limited in efficacy by viral sequence variability in emerging variants of concern (VOCs) and in deployment by the need for high doses. In this study, we leveraged the multi-specific, multi-affinity antibody (Multabody, MB) platform, derived from the human apoferritin protomer, to enable the multimerization of antibody fragments. MBs were shown to be highly potent, neutralizing SARS-CoV-2 at lower concentrations than their corresponding mAb counterparts. In mice infected with SARS-CoV-2, a tri-specific MB targeting three regions within the SARS-CoV-2 receptor binding domain was protective at a 30-fold lower dose than a cocktail of the corresponding mAbs. Furthermore, we showed in vitro that mono-specific MBs potently neutralize SARS-CoV-2 VOCs by leveraging augmented avidity, even when corresponding mAbs lose their ability to neutralize potently, and that tri-specific MBs expanded the neutralization breadth beyond SARS-CoV-2 to other sarbecoviruses. Our work demonstrates how avidity and multi-specificity combined can be leveraged to confer protection and resilience against viral diversity that exceeds that of traditional monoclonal antibody therapies.

Glycosylated nanoparticle-based PfCSP vaccine confers long-lasting antibody responses and sterile protection in mouse malaria model.

The development of an effective and durable vaccine remains a central goal in the fight against malaria. Circumsporozoite protein (CSP) is the major surface protein of sporozoites and the target of the only licensed Plasmodium falciparum (Pf) malaria vaccine, RTS,S/AS01. However, vaccine efficacy is low and short-lived, highlighting the need for a second-generation vaccine with superior efficacy and durability. Here, we report a Helicobacter pylori apoferritin-based nanoparticle immunogen that elicits strong B cell responses against PfCSP epitopes that are targeted by the most potent human monoclonal antibodies. Glycan engineering of the scaffold and fusion of an exogenous T cell epitope enhanced the anti-PfCSP B cell response eliciting strong, long-lived and protective humoral immunity in mice. Our study highlights the power of rational vaccine design to generate a highly efficacious second-generation anti-infective malaria vaccine candidate and provides the basis for its further development.

Molecular and functional properties of human Plasmodium falciparum CSP C-terminus antibodies.

Human monoclonal antibodies (mAbs) against the central repeat and junction domain of Plasmodium falciparum circumsporozoite protein (PfCSP) have been studied extensively to guide malaria vaccine design compared to antibodies against the PfCSP C terminus. Here, we describe the molecular characteristics and protective potential of 73 germline and mutated human mAbs against the highly immunogenic PfCSP C-terminal domain. Two mAbs recognized linear epitopes in the C-terminal linker with sequence similarity to repeat and junction motifs, whereas all others targeted conformational epitopes in the α-thrombospondin repeat (α-TSR) domain. Specificity for the polymorphic Th2R/Th3R but not the conserved RII+/CS.T3 region in the α-TSR was associated with IGHV3-21/IGVL3-21 or IGLV3-1 gene usage. Although the C terminus specific mAbs showed signs of more efficient affinity maturation and class-switching compared to anti-repeat mAbs, live sporozoite binding and inhibitory activity was limited to a single C-linker reactive mAb with cross-reactivity to the central repeat and junction. The data provide novel insights in the human anti-C-linker and anti-α-TSR antibody response that support exclusion of the PfCSP C terminus from malaria vaccine designs.

High-density binding to Plasmodium falciparum circumsporozoite protein repeats by inhibitory antibody elicited in mouse with human immunoglobulin repertoire.

Antibodies targeting the human malaria parasite Plasmodium falciparum circumsporozoite protein (PfCSP) can prevent infection and disease. PfCSP contains multiple central repeating NANP motifs; some of the most potent anti-infective antibodies against malaria bind to these repeats. Multiple antibodies can bind the repeating epitopes concurrently by engaging into homotypic Fab-Fab interactions, which results in the ordering of the otherwise largely disordered central repeat into a spiral. Here, we characterize IGHV3-33/IGKV1-5-encoded monoclonal antibody (mAb) 850 elicited by immunization of transgenic mice with human immunoglobulin loci. mAb 850 binds repeating NANP motifs with picomolar affinity, potently inhibits Plasmodium falciparum (Pf) in vitro and, when passively administered in a mouse challenge model, reduces liver burden to a similar extent as some of the most potent anti-PfCSP mAbs yet described. Like other IGHV3-33/IGKV1-5-encoded anti-NANP antibodies, mAb 850 primarily utilizes its HCDR3 and germline-encoded aromatic residues to recognize its core NANP motif. Biophysical and cryo-electron microscopy analyses reveal that up to 19 copies of Fab 850 can bind the PfCSP repeat simultaneously, and extensive homotypic interactions are observed between densely-packed PfCSP-bound Fabs to indirectly improve affinity to the antigen. Together, our study expands on the molecular understanding of repeat-induced homotypic interactions in the B cell response against PfCSP for potently protective mAbs against Pf infection.

Multivalency transforms SARS-CoV-2 antibodies into ultrapotent neutralizers.

SARS-CoV-2, the virus responsible for COVID-19, has caused a global pandemic. Antibodies can be powerful biotherapeutics to fight viral infections. Here, we use the human apoferritin protomer as a modular subunit to drive oligomerization of antibody fragments and transform antibodies targeting SARS-CoV-2 into exceptionally potent neutralizers. Using this platform, half-maximal inhibitory concentration (IC50) values as low as 9 × 10-14 M are achieved as a result of up to 10,000-fold potency enhancements compared to corresponding IgGs. Combination of three different antibody specificities and the fragment crystallizable (Fc) domain on a single multivalent molecule conferred the ability to overcome viral sequence variability together with outstanding potency and IgG-like bioavailability. The MULTi-specific, multi-Affinity antiBODY (Multabody or MB) platform thus uniquely leverages binding avidity together with multi-specificity to deliver ultrapotent and broad neutralizers against SARS-CoV-2. The modularity of the platform also makes it relevant for rapid evaluation against other infectious diseases of global health importance. Neutralizing antibodies are a promising therapeutic for SARS-CoV-2.

A high-affinity antibody against the CSP N-terminal domain lacks Plasmodium falciparum inhibitory activity.

Malaria is a global health concern, and research efforts are ongoing to develop a superior vaccine to RTS,S/AS01. To guide immunogen design, we seek a comprehensive understanding of the protective humoral response against Plasmodium falciparum (Pf) circumsporozoite protein (PfCSP). In contrast to the well-studied responses to the repeat region and the C-terminus, the antibody response against the N-terminal domain of PfCSP (N-CSP) remains obscure. Here, we characterized the molecular recognition and functional efficacy of the N-CSP-specific monoclonal antibody 5D5. The crystal structure at 1.85-Å resolution revealed that 5D5 binds an α-helical epitope in N-CSP with high affinity through extensive shape and charge complementarity and the unusual utilization of an antibody N-linked glycan. Nevertheless, functional studies indicated low 5D5 binding to live Pf sporozoites and lack of sporozoite inhibition in vitro and in vivo. Overall, our data do not support the inclusion of the 5D5 N-CSP epitope into the next generation of CSP-based vaccines.

Evolution of protective human antibodies against Plasmodium falciparum circumsporozoite protein repeat motifs.

The circumsporozoite protein of the human malaria parasite Plasmodium falciparum (PfCSP) is the main target of antibodies that prevent the infection and disease, as shown in animal models. However, the limited efficacy of the PfCSP-based vaccine RTS,S calls for a better understanding of the mechanisms driving the development of the most potent human PfCSP antibodies and identification of their target epitopes. By characterizing 200 human monoclonal PfCSP antibodies induced by sporozoite immunization, we establish that the most potent antibodies bind around a conserved (N/D)PNANPN(V/A) core. High antibody affinity to the core correlates with protection from parasitemia in mice and evolves around the recognition of NANP motifs. The data suggest that the rational design of a next-generation PfCSP vaccine that elicits high-affinity antibody responses against the core epitope will promote the induction of protective humoral immune responses.

Frequency of hematologic malignancies in the population of Arica, Chile.

Hematologic diseases are a heterogeneous group of malignancies that affect people worldwide such as leukemia, lymphoma and multiple myelomas. The aim of this study was to characterize the frequency of hematological diseases in the population of Arica, Chile (18°S, 70°W), between 2011 and 2014. A total of 108 cases of hematologic malignancies were registered at Dr. Juan Noé Crevani Regional Hospital in this period; 40 male and 52 female cases were included in this retrospective and descriptive analysis. The overall median age at diagnosis for hematological malignancies was 59 years (range, 17 to 96 years). The results indicated that the frequency of hematological diseases such as non-Hodgkin lymphoma and leukemia was not associated with sex, ethnicity and type of disease. However, in 2012 there was an increased number of cases of Hodgkin lymphoma compared with any other year in the study, whereas the number of multiple myeloma cases decreased between 2011 and 2014. No significant differences were observed among different types of disease, nor among the types of leukemia. However, when intervals of age were considered, it was revealed that patients >75 years had the highest incidence of hematological malignancies, mainly multiple myeloma, compared with other age groups. However, young adults were more commonly diagnosed with Hodgkin lymphoma than other disease types. A non-significant difference was observed in leukemia between 2011 and 2014 when sex was taken into consideration, in which the incidence rate was higher in females compared with males. Hodgkin lymphoma was most commonly at stage II and non-Hodgkin lymphoma was most commonly at stage IV. No significant differences were observed between the nodal and extranodal type, mixed cellularity and nodular sclerosis or in the morphology of non-Hodgkin lymphoma cell type. Overall, there was a decrease in the frequency of hematological malignancies between 2011 and 2014, but no significant differences were observed in males or females. This study provided for the first time the pattern and distribution of hematological diseases in Arica, Chile.

Fracturas mandibulares en el servicio de otorrinolaringología y cirugía maxilofacial: experiencia en las características clínicas, diagnósticas y de tratamiento en el Hospital San José / Mandibular fractures in the otorhinolaryngology and maxillofacial surgery service: experience in clinical, diagnostic and treatment characteristics at the San José Hospital

Introducción: el trauma facial es una de las urgencias más frecuentes del servicio de otorrinolaringología y cirugía maxilofacial. El tratamiento debe ser dirigido a identificar la causa y el tipo de fractura e implica que puede ser conservador o quirúrgico. Objetivo: describir la experiencia clínica y diagnóstica de las fracturas mandibulares en el servicio de otorrinolaringología y cirugía maxilofacial del Hospital San José de Bogotá entre 2014 y 2018. Diseño: estudio observacional descriptivo. Metodología: Se reclutó una cohorte de pacientes con diagnóstico de fractura mandibular en el Hospital de San José entre 2014 a 2018. Se describieron las principales características clínicas y demográficas, hallazgos imagenológicos, tipo de fractura, tratamiento, complicaciones y recidivas. Resultados: se incluyeron 25 casos de pacientes con fractura mandibular durante el período descrito. El 72 % de los pacientes fueron del sexo masculino, con edad promedio de 32 (DS 11,23) años. Con etiología por: caídas, la más frecuente (40 %), accidente de tránsito (32 %) y riña callejera (16 %). Las regiones anatómicas comprometidas con mayor frecuencia fueron el cóndilo (20 %), ángulo (12 %) y el área parasinfisiaria (12 %). El manejo quirúrgico estuvo presente en el 56 % de los pacientes, en los que se utilizó el abordaje oral en el 100 % de los casos. Conclusión: las fracturas mandibulares son frecuentes en hombres y comprometen con mayor frecuencia al cóndilo de la mandíbula. Según el tipo de fractura y el grado de compromiso, el manejo puede ser conservador o quirúrgico. Con baja frecuencia en complicaciones y recidiva.

Introduction: facial trauma is one of the most frequent emergencies of the otolaryngology and maxillofacial surgery service..Treatment should be aimed at identifying the cause and type of fracture and imply that it can be conservative and surgical to provide adequate knowledge and management for this type of pathology. Objective: to describe the experience in the conservative and surgical management of fractures. mandibular in the otolaryngology and maxillofacial surgery department of the San José Hospital in Bogotá between 2014 and 2018. Design: descriptive study. Methods: a cohort of patients with a diagnosis of mandibular fracture was enrolled at the Hospital de San José between 2014 and 2018. The main clinical and demographic characteristics, imaging findings, type of fracture, treatment, complications and recurrences were describe. Results: 25 cases of patients with mandibular fracture were included during the period described.72 % of the patients were men, with an average age of 32.32 years (DS11.23). With etiology due to falls, the most frequent cases (40 %), followed by traffic accidents (32 %) and street disputes (16 %) The anatomical regions frequently compromised are: the condyle (20 %), angle (12 %), parasinfisiary (12 %). Surgical treatment was present in 56 % of these patients, 100 % oral approach was used. Conclusion: mandibular fractures are common in men, and most often compromise the jaw condyle. Depending on the type of fracture and the degree of commitment, the treatment can be conservative or surgical. With low frequency in complications and recurrence.