The continuous emergence of SARS-CoV-2 variants of concern with mutated spike receptor binding do... more The continuous emergence of SARS-CoV-2 variants of concern with mutated spike receptor binding domains has rendered many therapeutic mAbs ineffective. To date, there are no clinically authorized therapeutic antibodies effective against the predominant circulating sub-lineages BQ and XBB. Here, we report the isolation of broad and potent neutralizing HuMabs from a Danish healthcare worker infected with SARS-CoV-2 early in the pandemic. These HuMabs include a novel and genetically unique non-RBD-specific HuMab (K501SP6) which can neutralize Omicron sub-lineages BQ and XBB, and an RBD-specific HuMab (K501SP3) with high potency towards earlier circulating variants but was escaped by Omicron sub-lineages BA.5, BQ and XBB through F486 and E484 substitutions. Characterizing SARS-CoV-2 spike-specific HuMabs, including broadly reactive non-RBD-specific HuMabs, can give insight into the immune mechanisms involved in neutralization and immune evasion, which can be a valuable addition to alread...
Although experts in the field have agreed on the malaria vaccine technology roadmap that should b... more Although experts in the field have agreed on the malaria vaccine technology roadmap that should be followed (http://www.malariavaccineroadmap.net/), the path towards an effective malaria vaccine remains littered with intellectual and practical pot-holes. The animal models that are currently available are problematic, and current understanding of the exact mechanisms and targets of protective immune responses is incomplete. However, recent technological advances might help overcome some of these hurdles.
Malaria during pregnancy is a major global health problem caused by infection with Plasmodium fal... more Malaria during pregnancy is a major global health problem caused by infection with Plasmodium falciparum parasites. Severe effects arise from the accumulation of infected erythrocytes in the placenta. Here, erythrocytes infected by late blood-stage parasites adhere to placental chondroitin sulphate A (CS) via VAR2CSA-type P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion proteins. Immunity to placental malaria is acquired through exposure and mediated through antibodies to VAR2CSA. Through evolution, the VAR2CSA proteins have diversified in sequence to escape immune recognition but retained their overall macromolecular structure to maintain CS binding affinity. This structural conservation may also have allowed development of broadly reactive antibodies to VAR2CSA in immune women. Here we show the negative stain and cryo-EM structure of the only known broadly reactive human monoclonal antibody, PAM1.4, in complex with VAR2CSA. The data shows how PAM1.4’s broad VAR2CSA r...
BackgroundThe development of vaccine candidates for COVID‐19, and the administration of booster v... more BackgroundThe development of vaccine candidates for COVID‐19, and the administration of booster vaccines, has meant a significant reduction in COVID‐19 related deaths world‐wide and the easing of global restrictions. However, new variants of SARS‐CoV‐2 have emerged with less susceptibility to vaccine induced immunity leading to breakthrough infections among vaccinated people. It is generally acknowledged that immunoglobulins play the major role in immune‐protection, primarily through binding to the SARS‐COV‐2 receptor binding domain (RBD) and thereby inhibiting viral binding to the ACE2 receptor. However, there are limited investigations of anti‐RBD isotypes (IgM, IgG, IgA) and IgG subclasses (IgG1–4) over the course of vaccination and breakthrough infection.MethodIn this study, SARS‐CoV‐2 humoral immunity is examined in a single subject with unique longitudinal sampling. Over a two year period, the subject received three doses of vaccine, had two active breakthrough infections and 22 blood samples collected. Serological testing included anti‐nucleocapsid total antibodies, anti‐RBD total antibodies, IgG, IgA, IgM and IgG subclasses, neutralization and ACE2 inhibition against the wildtype (WT), Delta and Omicron variants.ResultsVaccination and breakthrough infections induced IgG, specifically IgG1 and IgG4 as well as IgM and IgA. IgG1 and IgG4 responses were cross reactive and associated with broad inhibition.ConclusionThe findings here provide novel insights into humoral immune response characteristics associated with SARS‐CoV‐2 breakthrough infections.
<p>Levels (AU) of IgG specific for PfRH5 (A), CyRPA (B), Pf113 (C), EBA175 (D), GLURP-R0 (E... more <p>Levels (AU) of IgG specific for PfRH5 (A), CyRPA (B), Pf113 (C), EBA175 (D), GLURP-R0 (E) and GLURP-R2 (F) in plasma of individual children according to clinical category: SM (severe P. falciparum malaria), UM (uncomplicated P. falciparum malaria), FC (non-parasitemic febrile controls), AC (asymptomatic controls), HC (non-parasitemic healthy controls). Please refer to Materials and Methods for category definitions. The number of individuals with IgG above cut-off and the total number of individuals in each clinical category are given along the top of each panel. Horizontal lines along the top of the panels indicate statistically significant (P<0.05) differences between groups. Data presentation otherwise as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0198371#pone.0198371.g001" target="_blank">Fig 1B</a>. The presented data is from one experiment.</p
<p>Plasma levels of IgG specific for PfRH5 (A, D), CyRPA (B, E), and Pf113 (C, F) in childr... more <p>Plasma levels of IgG specific for PfRH5 (A, D), CyRPA (B, E), and Pf113 (C, F) in children with P. falciparum malaria (Day 0), and in the same children two weeks (Day 14) and six weeks (Day 42) later. Temporal changes in levels of IgG in individual children (A-C) and in the cohort mean IgG level (D-F). Data from individual children are connected by lines (A-C). Cohort running means (heavy lines) and their 95% confidence intervals (thin lines), calculated as described previously [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0198371#pone.0198371.ref034" target="_blank">34</a>], as well as calculated catabolic decay from Day 14 (dashed lines) are shown (D-F). Negative cut-offs (shaded areas) are shown (all panels). The presented data is from one experiment.</p
Rosetting, the adhesion of Plasmodium falciparum-infected erythrocytes to uninfected erythrocytes... more Rosetting, the adhesion of Plasmodium falciparum-infected erythrocytes to uninfected erythrocytes, involves clonal variants of the parasite protein P. falciparum erythrocyte mem-brane protein 1 (PfEMP1) and soluble serum factors. While rosetting is a well-known pheno-typic marker of parasites associated with severe malaria, the reason for this association remains unclear, as do the molecular details of the interaction between the infected erythro-cyte (IE) and the adhering erythrocytes. Here, we identify for the first time a single serum factor, the abundant serum protease inhibitor α2-macroglobulin (α2M), which is both required and sufficient for rosetting mediated by the PfEMP1 protein HB3VAR06 and some other rosette-mediating PfEMP1 proteins. We map the α2M binding site to the C terminal end of HB3VAR06, and demonstrate that α2M can bind at least four HB3VAR06 proteins, plausibly augmenting their combined avidity for host receptors. IgM has previously been identified as a rosette...
Malaria is a deadly infectious disease primarily caused by the parasite Plasmodium falciparum . I... more Malaria is a deadly infectious disease primarily caused by the parasite Plasmodium falciparum . It remains a major global health problem, and there is no highly effective vaccine. A parasite protein called RH5 is centrally involved in the invasion of host red blood cells, making it—and the other parasite proteins it interacts with—promising vaccine targets. We recently identified a protein called P113 that binds RH5, suggesting that it anchors RH5 to the parasite surface. In this paper, we use structural biology to locate and characterize the RH5 binding region on P113. These findings will be important to guide the development of new antimalarial vaccines to ultimately prevent this disease, which affects some of the poorest people on the planet.
The continuous emergence of SARS-CoV-2 variants of concern with mutated spike receptor binding do... more The continuous emergence of SARS-CoV-2 variants of concern with mutated spike receptor binding domains has rendered many therapeutic mAbs ineffective. To date, there are no clinically authorized therapeutic antibodies effective against the predominant circulating sub-lineages BQ and XBB. Here, we report the isolation of broad and potent neutralizing HuMabs from a Danish healthcare worker infected with SARS-CoV-2 early in the pandemic. These HuMabs include a novel and genetically unique non-RBD-specific HuMab (K501SP6) which can neutralize Omicron sub-lineages BQ and XBB, and an RBD-specific HuMab (K501SP3) with high potency towards earlier circulating variants but was escaped by Omicron sub-lineages BA.5, BQ and XBB through F486 and E484 substitutions. Characterizing SARS-CoV-2 spike-specific HuMabs, including broadly reactive non-RBD-specific HuMabs, can give insight into the immune mechanisms involved in neutralization and immune evasion, which can be a valuable addition to alread...
Although experts in the field have agreed on the malaria vaccine technology roadmap that should b... more Although experts in the field have agreed on the malaria vaccine technology roadmap that should be followed (http://www.malariavaccineroadmap.net/), the path towards an effective malaria vaccine remains littered with intellectual and practical pot-holes. The animal models that are currently available are problematic, and current understanding of the exact mechanisms and targets of protective immune responses is incomplete. However, recent technological advances might help overcome some of these hurdles.
Malaria during pregnancy is a major global health problem caused by infection with Plasmodium fal... more Malaria during pregnancy is a major global health problem caused by infection with Plasmodium falciparum parasites. Severe effects arise from the accumulation of infected erythrocytes in the placenta. Here, erythrocytes infected by late blood-stage parasites adhere to placental chondroitin sulphate A (CS) via VAR2CSA-type P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion proteins. Immunity to placental malaria is acquired through exposure and mediated through antibodies to VAR2CSA. Through evolution, the VAR2CSA proteins have diversified in sequence to escape immune recognition but retained their overall macromolecular structure to maintain CS binding affinity. This structural conservation may also have allowed development of broadly reactive antibodies to VAR2CSA in immune women. Here we show the negative stain and cryo-EM structure of the only known broadly reactive human monoclonal antibody, PAM1.4, in complex with VAR2CSA. The data shows how PAM1.4’s broad VAR2CSA r...
BackgroundThe development of vaccine candidates for COVID‐19, and the administration of booster v... more BackgroundThe development of vaccine candidates for COVID‐19, and the administration of booster vaccines, has meant a significant reduction in COVID‐19 related deaths world‐wide and the easing of global restrictions. However, new variants of SARS‐CoV‐2 have emerged with less susceptibility to vaccine induced immunity leading to breakthrough infections among vaccinated people. It is generally acknowledged that immunoglobulins play the major role in immune‐protection, primarily through binding to the SARS‐COV‐2 receptor binding domain (RBD) and thereby inhibiting viral binding to the ACE2 receptor. However, there are limited investigations of anti‐RBD isotypes (IgM, IgG, IgA) and IgG subclasses (IgG1–4) over the course of vaccination and breakthrough infection.MethodIn this study, SARS‐CoV‐2 humoral immunity is examined in a single subject with unique longitudinal sampling. Over a two year period, the subject received three doses of vaccine, had two active breakthrough infections and 22 blood samples collected. Serological testing included anti‐nucleocapsid total antibodies, anti‐RBD total antibodies, IgG, IgA, IgM and IgG subclasses, neutralization and ACE2 inhibition against the wildtype (WT), Delta and Omicron variants.ResultsVaccination and breakthrough infections induced IgG, specifically IgG1 and IgG4 as well as IgM and IgA. IgG1 and IgG4 responses were cross reactive and associated with broad inhibition.ConclusionThe findings here provide novel insights into humoral immune response characteristics associated with SARS‐CoV‐2 breakthrough infections.
<p>Levels (AU) of IgG specific for PfRH5 (A), CyRPA (B), Pf113 (C), EBA175 (D), GLURP-R0 (E... more <p>Levels (AU) of IgG specific for PfRH5 (A), CyRPA (B), Pf113 (C), EBA175 (D), GLURP-R0 (E) and GLURP-R2 (F) in plasma of individual children according to clinical category: SM (severe P. falciparum malaria), UM (uncomplicated P. falciparum malaria), FC (non-parasitemic febrile controls), AC (asymptomatic controls), HC (non-parasitemic healthy controls). Please refer to Materials and Methods for category definitions. The number of individuals with IgG above cut-off and the total number of individuals in each clinical category are given along the top of each panel. Horizontal lines along the top of the panels indicate statistically significant (P<0.05) differences between groups. Data presentation otherwise as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0198371#pone.0198371.g001" target="_blank">Fig 1B</a>. The presented data is from one experiment.</p
<p>Plasma levels of IgG specific for PfRH5 (A, D), CyRPA (B, E), and Pf113 (C, F) in childr... more <p>Plasma levels of IgG specific for PfRH5 (A, D), CyRPA (B, E), and Pf113 (C, F) in children with P. falciparum malaria (Day 0), and in the same children two weeks (Day 14) and six weeks (Day 42) later. Temporal changes in levels of IgG in individual children (A-C) and in the cohort mean IgG level (D-F). Data from individual children are connected by lines (A-C). Cohort running means (heavy lines) and their 95% confidence intervals (thin lines), calculated as described previously [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0198371#pone.0198371.ref034" target="_blank">34</a>], as well as calculated catabolic decay from Day 14 (dashed lines) are shown (D-F). Negative cut-offs (shaded areas) are shown (all panels). The presented data is from one experiment.</p
Rosetting, the adhesion of Plasmodium falciparum-infected erythrocytes to uninfected erythrocytes... more Rosetting, the adhesion of Plasmodium falciparum-infected erythrocytes to uninfected erythrocytes, involves clonal variants of the parasite protein P. falciparum erythrocyte mem-brane protein 1 (PfEMP1) and soluble serum factors. While rosetting is a well-known pheno-typic marker of parasites associated with severe malaria, the reason for this association remains unclear, as do the molecular details of the interaction between the infected erythro-cyte (IE) and the adhering erythrocytes. Here, we identify for the first time a single serum factor, the abundant serum protease inhibitor α2-macroglobulin (α2M), which is both required and sufficient for rosetting mediated by the PfEMP1 protein HB3VAR06 and some other rosette-mediating PfEMP1 proteins. We map the α2M binding site to the C terminal end of HB3VAR06, and demonstrate that α2M can bind at least four HB3VAR06 proteins, plausibly augmenting their combined avidity for host receptors. IgM has previously been identified as a rosette...
Malaria is a deadly infectious disease primarily caused by the parasite Plasmodium falciparum . I... more Malaria is a deadly infectious disease primarily caused by the parasite Plasmodium falciparum . It remains a major global health problem, and there is no highly effective vaccine. A parasite protein called RH5 is centrally involved in the invasion of host red blood cells, making it—and the other parasite proteins it interacts with—promising vaccine targets. We recently identified a protein called P113 that binds RH5, suggesting that it anchors RH5 to the parasite surface. In this paper, we use structural biology to locate and characterize the RH5 binding region on P113. These findings will be important to guide the development of new antimalarial vaccines to ultimately prevent this disease, which affects some of the poorest people on the planet.
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Papers by Lea Barfod