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Abstract With resistance to most antimalarials increasing, it is imperative that new drugs are developed. We previously identified an aryl acetamide compound, MMV006833 (M-833), that inhibited the ring-stage development of newly invaded merozoites. Here, we select parasites resistant to M-833 and identify mutations in the START lipid transfer protein (PF3D7_0104200, PfSTART1). Introducing PfSTART1 mutations into wildtype parasites reproduces resistance to M-833 as well as to more potent analogues. PfSTART1 binding to the analogues is validated using organic solvent-based Proteome Integral Solubility Alteration (Solvent PISA) assays. Imaging of invading merozoites shows the inhibitors prevent the development of ring-stage parasites potentially by inhibiting the expansion of the encasing parasitophorous vacuole membrane. The PfSTART1-targeting compounds also block transmission to mosquitoes and with multiple stages of the parasite’s lifecycle being affected, PfSTART1 represents a drug target with a new mechanism of action.

Apicomplexan parasites that reside within a parasitophorous vacuole harbor a conserved pore-forming protein that enables small-molecule transfer across the parasitophorous vacuole membrane (PVM). In Plasmodium parasites that cause malaria, this nutrient pore is formed by EXP2 which can complement the function of GRA17, an orthologous protein in Toxoplasma gondii. EXP2, however, has an additional function in Plasmodium parasites, serving also as the pore-forming component of the protein export machinery PTEX. To examine how EXP2 can play this additional role, transgenes that encoded truncations of EXP2, GRA17, hybrid GRA17-EXP2, or EXP2 under the transcriptional control of different promoters were expressed in EXP2 knockdown parasites to determine which could complement EXP2 function. This revealed that EXP2 is a unique pore-forming protein, and its protein export role in P. falciparum cannot be complemented by T. gondii GRA17. This was despite the addition of the EXP2 assembly strand and part of the linker helix to GRA17, which are regions necessary for the interaction of EXP2 with the other core PTEX components. This indicates that the body region of EXP2 plays a critical role in PTEX assembly and/or that the absence of other T. gondii GRA proteins in P. falciparum leads to its reduced efficiency of insertion into the PVM and complementation potential. Altering the timing and abundance of EXP2 expression did not affect protein export but affected parasite viability, indicating that the unique transcriptional profile of EXP2 when compared to other PTEX components enables it to serve an additional role in nutrient exchange.

The Plasmodium falciparum reticulocyte-binding protein homolog 5 (PfRH5) is the current leading blood-stage malaria vaccine candidate. PfRH5 functions as part of the pentameric PCRCR complex containing PTRAMP, CSS, PfCyRPA and PfRIPR, all of which are essential for infection of human red blood cells (RBCs). To trigger RBC invasion, PfRH5 engages with RBC protein basigin in a step termed the RH5-basigin binding stage. Although we know increasingly more about how antibodies specific for PfRH5 can block invasion, much less is known about how antibodies recognizing other members of the PCRCR complex can inhibit invasion. To address this, we performed live cell imaging using monoclonal antibodies (mAbs) which bind PfRH5 and PfCyRPA. We measured the degree and timing of the invasion inhibition, the stage at which it occurred, as well as subsequent events. We show that parasite invasion is blocked by individual mAbs, and the degree of inhibition is enhanced when combining a mAb specific for PfRH5 with one binding PfCyRPA. In addition to directly establishing the invasion-blocking capacity of the mAbs, we identified a secondary action of certain mAbs on extracellular parasites that had not yet invaded where the mAbs appeared to inactivate the parasites by triggering a developmental pathway normally only seen after successful invasion. These findings suggest that epitopes within the PfCyRPA-PfRH5 sub-complex that elicit these dual responses may be more effective immunogens than neighboring epitopes by both blocking parasites from invading and rapidly inactivating extracellular parasites. These two protective mechanisms, prevention of invasion and inactivation of uninvaded parasites, resulting from antibody to a single epitope indicate a possible route to the development of more effective vaccines.

M5717 is a promising antimalarial drug under development that acts against multiple stages of the life cycle of Plasmodium parasites by inhibiting the translation elongation factor 2 (PfeEF2), thereby preventing protein synthesis. The parasite clearance profile after drug treatment in preclinical studies in mice, and clinical trials in humans showed a notable delayed clearance phenotype whereby parasite infected red blood cells (iRBCs) persisted in the bloodstream for a significant period before eventual clearance. In a normal P. falciparum infection iRBCs sequester in the deep circulation by cytoadherence, allowing them to avoid surveillance and clearance in the spleen. We found that M5717 blocks parasite modification of their host red blood cells (RBCs) by preventing synthesis of new exported proteins, rather than by directly blocking the export of these proteins into the RBC compartment. Using in vitro models, we demonstrated that M5717 treated ring/trophozoite stage iRBCs became less rigid, and cytoadhered less well compared to untreated iRBCs. This indicates that in vivo persistence of M5717 treated iRBCs in the bloodstream is likely due to reduced cytoadherence and splenic clearance.

Background Clinically relevant aortic dilatation (>40 mm) and increased cardiovascular risk are common among retired professional American‐style football athletes. Among younger athletes, the effect of American‐style football participation on aortic size is incompletely understood. We sought to determine changes in aortic root (AR) size and associated cardiovascular phenotypes across the collegiate career. Methods and Results This was a multicenter, longitudinal repeated‐measures observational cohort study of athletes across 3 years of elite collegiate American‐style football participation. A total of 247 athletes (119 [48%] Black, 126 [51%] White, 2 [1%] Latino; 91 [37%] linemen, 156 [63%] non‐linemen) were enrolled as freshmen and studied at pre‐ and postseason year 1, postseason year 2 (N=140 athletes), and postseason year 3 (N=82 athletes). AR size was measured with transthoracic echocardiography. AR diameter increased over the study period from 31.7 (95% CI, 31.4–32.0) to 33.5 mm (95% CI, 33.1–33.8; P

With emerging resistance to frontline treatments, it is vital that new antimalarial drugs are identified to target Plasmodium falciparum. We have recently described a compound, MMV020291, as a specific inhibitor of red blood cell (RBC) invasion, and have generated analogues with improved potency. Here, we generated resistance to MMV020291 and performed whole genome sequencing of 3 MMV020291-resistant populations. This revealed 3 nonsynonymous single nucleotide polymorphisms in 2 genes; 2 in profilin (N154Y, K124N) and a third one in actin-1 (M356L). Using CRISPR-Cas9, we engineered these mutations into wild-type parasites, which rendered them resistant to MMV020291. We demonstrate that MMV020291 reduces actin polymerisation that is required by the merozoite stage parasites to invade RBCs. Additionally, the series inhibits the actin-1-dependent process of apicoplast segregation, leading to a delayed death phenotype. In vitro cosedimentation experiments using recombinant P. falciparum proteins indicate that potent MMV020291 analogues disrupt the formation of filamentous actin in the presence of profilin. Altogether, this study identifies the first compound series interfering with the actin-1/profilin interaction in P. falciparum and paves the way for future antimalarial development against the highly dynamic process of actin polymerisation.

The cation efflux pump Plasmodium falciparum ATPase 4 (PfATP4) maintains Na+ homeostasis in malaria parasites and has been implicated in the mechanism of action of many structurally diverse antimalarial agents, including >7% of the antimalarial compounds in the Medicines for Malaria Venture’s ‘Malaria Box’ and ‘Pathogen Box’. Recent screens of the ‘Malaria Box’ and ‘Pathogen Box’ revealed that many PfATP4 inhibitors prevent parasites from exiting their host red blood cell (egress) or entering new host cells (invasion), suggesting that these compounds may have additional molecular targets involved in egress or invasion. Here, we demonstrate that five PfATP4 inhibitors reduce egress but not invasion. These compounds appear to inhibit egress by blocking the activation of protein kinase G, an enzyme that, once stimulated, rapidly activates parasite egress. We establish a direct link between egress and PfATP4 function by showing that the inhibition of egress is attenuated in a Na+-depleted environment and in parasites with a mutation in pfatp4. Finally, we show that PfATP4 inhibitors induce host cell lysis when administered prior to the completion of parasite replication. Since host cell lysis mimics egress but is not followed by invasion, this phenomenon likely explains why several PfATP4 inhibitors were previously classified as invasion inhibitors. Collectively, our results confirm that PfATP4-mediated Na+ efflux is critical to the regulation of parasite egress.

Background Ventricular–arterial (VA) coupling is defined as the ratio between arterial elastance (EA) and left ventricular elastance (ELV). VA uncoupling, as occurs in hypertensive heart disease, is associated with adverse outcomes. This study sought to determine the relationship between American football (AF)–associated hypertension and VA uncoupling. Methods and Results This was a multicenter, longitudinal, and repeated measures observational study of collegiate AF athletes across 3 years of AF participation. Of 200 freshman athletes initially enrolled, 142 (67 Black [47%]/75 White [53%], 58 linemen [41%]/84 nonlinemen [59%]) were prospectively studied with echocardiography and applanation tonometry. Primary echocardiographic VA coupling outcome measures were EA/ELV and ΔEA/ELV, with increased EA/ELV indicating VA uncoupling. Adjusting for race and player position, AF athletes demonstrated increased EA/ELV (mean [95% CI]Δ, 0.10 [0.04–0.15]; P=0.001) and systolic blood pressure (SBP) (mean [95% CI]Δ, 11.4 [8.3–14.5] mm Hg, P

Plasmodium falciparum exports ~10% of its proteome into its host erythrocyte to modify the host cell's physiology. The Plasmodium export element (PEXEL) motif contained within the N-terminus of most exported proteins directs the trafficking of those proteins into the erythrocyte. To reach the host cell, the PEXEL motif of exported proteins is processed by the endoplasmic reticulum (ER) resident aspartyl protease plasmepsin V. Then, following secretion into the parasite-encasing parasitophorous vacuole, the mature exported protein must be unfolded and translocated across the parasitophorous vacuole membrane by the Plasmodium translocon of exported proteins (PTEX). PTEX is a protein-conducting channel consisting of the pore-forming protein EXP2, the protein unfoldase HSP101, and structural component PTEX150. The mechanism of how exported proteins are specifically trafficked from the parasite's ER following PEXEL cleavage to PTEX complexes on the parasitophorous vacuole membrane is currently not understood. Here, we present evidence that EXP2 and PTEX150 form a stable subcomplex that facilitates HSP101 docking. We also demonstrate that HSP101 localises both within the parasitophorous vacuole and within the parasite's ER throughout the ring and trophozoite stage of the parasite, coinciding with the timeframe of protein export. Interestingly, we found that HSP101 can form specific interactions with model PEXEL proteins in the parasite's ER, irrespective of their PEXEL processing status. Collectively, our data suggest that HSP101 recognises and chaperones PEXEL proteins from the ER to the parasitophorous vacuole and given HSP101's specificity for the EXP2-PTEX150 subcomplex, this provides a mechanism for how exported proteins are specifically targeted to PTEX for translocation into the erythrocyte.

Plasmodium-infected red blood cells export virulence factors, such asPfEMP1, to the cell surface. Here, the authors identify a protein complex termed EPIC that interacts with PfEMP1 during export, and they show that knockdown of an EPIC component affects parasite virulence.

ABSTRACT Understanding the mechanisms behind host cell invasion by Plasmodium falciparum remains a major hurdle to developing antimalarial therapeutics that target the asexual cycle and the symptomatic stage of malaria. Host cell entry is enabled by a multitude of precisely timed and tightly regulated receptor-ligand interactions. Cyclic nucleotide signaling has been implicated in regulating parasite invasion, and an important downstream effector of the cAMP-signaling pathway is protein kinase A (PKA), a cAMP-dependent protein kinase. There is increasing evidence that P. falciparum PKA (PfPKA) is responsible for phosphorylation of the cytoplasmic domain of P. falciparum apical membrane antigen 1 (PfAMA1) at Ser610, a cAMP-dependent event that is crucial for successful parasite invasion. In the present study, CRISPR-Cas9 and conditional gene deletion (dimerizable cre) technologies were implemented to generate a P. falciparum parasite line in which expression of the catalytic subunit of PfPKA (PfPKAc) is under conditional control, demonstrating highly efficient dimerizable Cre recombinase (DiCre)-mediated gene excision and complete knockdown of protein expression. Parasites lacking PfPKAc show severely reduced growth after one intraerythrocytic growth cycle and are deficient in host cell invasion, as highlighted by live-imaging experiments. Furthermore, PfPKAc-deficient parasites are unable to phosphorylate PfAMA1 at Ser610. This work not only identifies an essential role for PfPKAc in the P. falciparum asexual life cycle but also confirms that PfPKAc is the kinase responsible for phosphorylating PfAMA1 Ser610. IMPORTANCE Malaria continues to present a major global health burden, particularly in low-resource countries. Plasmodium falciparum, the parasite responsible for the most severe form of malaria, causes disease through rapid and repeated rounds of invasion and replication within red blood cells. Invasion into red blood cells is essential for P. falciparum survival, and the molecular events mediating this process have gained much attention as potential therapeutic targets. With no effective vaccine available, and with the emergence of resistance to antimalarials, there is an urgent need for the development of new therapeutics. Our research has used genetic techniques to provide evidence of an essential protein kinase involved in P. falciparum invasion. Our work adds to the current understanding of parasite signaling processes required for invasion, highlighting PKA as a potential drug target to inhibit invasion for the treatment of malaria.

The development of effective malaria vaccines remains a global health priority. Currently, the most advanced vaccine, known as RTS,S, has only shown modest efficacy in clinical trials. Thus, the development of more efficacious vaccines by improving the formulation of RTS,S for increased efficacy or to interrupt malaria transmission are urgently needed. The RTS,S vaccine is based on the presentation of a fragment of the sporozoite antigen on the surface of virus-like particles (VLPs) based on human hepatitis B virus (HBV). In this study, we have developed and evaluated a novel VLP platform based on duck HBV (known as Metavax) for malaria vaccine development. This platform can incorporate large and complex proteins into VLPs and is produced in a Hansenula cell line compatible with cGMP vaccine production. Here, we have established the expression of leading P. falciparum malaria vaccine candidates as VLPs. This includes Pfs230 and Pfs25, which are candidate transmission-blocking vaccine antigens. We demonstrated that the VLPs effectively induce antibodies to malaria vaccine candidates with minimal induction of antibodies to the duck-HBV scaffold antigen. Antibodies to Pfs230 also recognised native protein on the surface of gametocytes, and antibodies to both Pfs230 and Pfs25 demonstrated transmission-reducing activity in standard membrane feeding assays. These results establish the potential utility of this VLP platform for malaria vaccines, which may be suitable for the development of multi-component vaccines that achieve high vaccine efficacy and transmission-blocking immunity.

Malaria parasites remodel their host erythrocytes to gain nutrients and avoid the immune system. Host erythrocytes are modified by hundreds of effector proteins exported from the parasite into the host cell. Protein export is mediated by the PTEX translocon comprising five core components of which EXP2 is considered to form the putative pore that spans the vacuole membrane enveloping the parasite within its erythrocyte. To explore the function and importance of EXP2 for parasite survival in the asexual blood stage of Plasmodium falciparum we inducibly knocked down the expression of EXP2. Reduction in EXP2 expression strongly reduced parasite growth proportional to the degree of protein knockdown and tended to stall development about half way through the asexual cell cycle. Once the knockdown inducer was removed and EXP2 expression restored, parasite growth recovered dependent upon the length and degree of knockdown. To establish EXP2 function and hence the basis for growth reduction, the trafficking of an exported protein was monitored following EXP2 knockdown. This resulted in severe attenuation of protein export and is consistent with EXP2, and PTEX in general, being the conduit for export of proteins into the host compartment.

Plasmodium falciparum parasites, the causative agents of malaria, modify their host erythrocyte to render them permeable to supplementary nutrient uptake from the plasma and for removal of toxic waste. Here we investigate the contribution of the rhoptry protein RhopH2, in the formation of new permeability pathways (NPPs) in Plasmodium-infected erythrocytes. We show RhopH2 interacts with RhopH1, RhopH3, the erythrocyte cytoskeleton and exported proteins involved in host cell remodeling. Knockdown of RhopH2 expression in cycle one leads to a depletion of essential vitamins and cofactors and decreased de novo synthesis of pyrimidines in cycle two. There is also a significant impact on parasite growth, replication and transition into cycle three. The uptake of solutes that use NPPs to enter erythrocytes is also reduced upon RhopH2 knockdown. These findings provide direct genetic support for the contribution of the RhopH complex in NPP activity and highlight the importance of NPPs to parasite survival.

Malaria is caused by five different Plasmodium spp. in humans each of which modifies the host erythrocyte to survive and replicate. The two main causes of malaria, P. falciparum and P. vivax, differ in their ability to cause severe disease, mainly due to differences in the cytoadhesion of infected erythrocytes (IE) in the microvasculature. Cytoadhesion of P. falciparum in the brain leads to a large number of deaths each year and is a consequence of exported parasite proteins, some of which modify the erythrocyte cytoskeleton while others such as PfEMP1 project onto the erythrocyte surface where they bind to endothelial cells. Here we investigate the effects of knocking out an exported Hsp70-type chaperone termed Hsp70-x that is present in P. falciparum but not P. vivax. Although the growth of Δhsp70-x parasites was unaffected, the export of PfEMP1 cytoadherence proteins was delayed and Δhsp70-x IE had reduced adhesion. The Δhsp70-x IE were also more rigid than wild-type controls indicating changes in the way the parasites modified their host erythrocyte. To investigate the cause of this, transcriptional and translational changes in exported and chaperone proteins were monitored and some changes were observed. We propose that PfHsp70-x is not essential for survival in vitro, but may be required for the efficient export and functioning of some P. falciparum exported proteins.

The most severe form of malaria in humans is caused by the protozoan parasite Plasmodium falciparum. The invasive form of malaria parasites is termed a merozoite and it employs an array of parasite proteins that bind to the host cell to mediate invasion. In Plasmodium falciparum, the erythrocyte binding-like (EBL) and reticulocyte binding-like (Rh) protein families are responsible for binding to specific erythrocyte receptors for invasion and mediating signalling events that initiate active entry of the malaria parasite. Here we have addressed the role of the cytoplasmic tails of these proteins in activating merozoite invasion after receptor engagement. We show that the cytoplasmic domains of these type 1 membrane proteins are phosphorylated in vitro. Depletion of PfCK2, a kinase implicated to phosphorylate these cytoplasmic tails, blocks P. falciparum invasion of red blood cells. We identify the crucial residues within the PfRh4 cytoplasmic domain that are required for successful parasite invasion. Live cell imaging of merozoites from these transgenic mutants show they attach but do not penetrate erythrocytes implying the PfRh4 cytoplasmic tail conveys signals important for the successful completion of the invasion process.

During blood stage Plasmodium falciparum infection, merozoites invade uninfected erythrocytes via a complex, multistep process involving a series of distinct receptor-ligand binding events. Understanding each element in this process increases the potential to block the parasite's life cycle via drugs or vaccines. To investigate specific receptor-ligand interactions, they were systematically blocked using a combination of genetic deletion, enzymatic receptor cleavage and inhibition of binding via antibodies, peptides and small molecules, and the resulting temporal changes in invasion and morphological effects on erythrocytes were filmed using live cell imaging. Analysis of the videos have shown receptor-ligand interactions occur in the following sequence with the following cellular morphologies; 1) an early heparin-blockable interaction which weakly deforms the erythrocyte, 2) EBA and PfRh ligands which strongly deform the erythrocyte, a process dependant on the merozoite's actin-myosin motor, 3) a PfRh5-basigin binding step which results in a pore or opening between parasite and host through which it appears small molecules and possibly invasion components can flow and 4) an AMA1-RON2 interaction that mediates tight junction formation, which acts as an anchor point for internalization. In addition to enhancing general knowledge of apicomplexan biology, this work provides a rational basis to combine sequentially acting merozoite vaccine candidates in a single multi-receptor-blocking vaccine.

Drug discovery is a key part of malaria control and eradication strategies, and could benefit from sensitive and affordable assays to quantify parasite growth and to help identify the targets of potential anti-malarial compounds. Bioluminescence, achieved through expression of exogenous luciferases, is a powerful tool that has been applied in studies of several aspects of parasite biology and high throughput growth assays. We have expressed the new reporter NanoLuc (Nluc) luciferase in Plasmodium falciparum and showed it is at least 100 times brighter than the commonly used firefly luciferase. Nluc brightness was explored as a means to achieve a growth assay with higher sensitivity and lower cost. In addition we attempted to develop other screening assays that may help interrogate libraries of inhibitory compounds for their mechanism of action. To this end parasites were engineered to express Nluc in the cytoplasm, the parasitophorous vacuole that surrounds the intraerythrocytic parasite or exported to the red blood cell cytosol. As proof-of-concept, these parasites were used to develop functional screening assays for quantifying the effects of Brefeldin A, an inhibitor of protein secretion, and Furosemide, an inhibitor of new permeation pathways used by parasites to acquire plasma nutrients.

Targeted regulation of protein levels is an important tool to gain insights into the role of proteins essential to cell function and development. In recent years, a method based on mutated forms of the human FKBP12 has been established and used to great effect in various cell types to explore protein function. The mutated FKBP protein, referred to as destabilization domain (DD) tag when fused with a native protein at the N- or C-terminus targets the protein for proteosomal degradation. Regulated expression is achieved via addition of a compound, Shld-1, that stabilizes the protein and prevents degradation. A limited number of studies have used this system to provide powerful insight into protein function in the human malaria parasite Plasmodium falciparum. In order to better understand the DD inducible system in P. falciparum, we studied the effect of Shld-1 on parasite growth, demonstrating that although development is not impaired, it is delayed, requiring the appropriate controls for phenotype interpretation. We explored the quantified regulation of reporter Green Fluorescent Protein (GFP) and luciferase constructs fused to three DD variants in parasite cells either via transient or stable transfection. The regulation obtained with the original FKBP derived DD domain was compared to two triple mutants DD24 and DD29, which had been described to provide better regulation for C-terminal tagging in other cell types. When cloned to the C-terminal of reporter proteins, DD24 provided the strongest regulation allowing reporter activity to be reduced to lower levels than DD and to restore the activity of stabilised proteins to higher levels than DD29. Importantly, DD24 has not previously been applied to regulate proteins in P. falciparum. The possibility of regulating an exported protein was addressed by targeting the Ring-Infected Erythrocyte Surface Antigen (RESA) at its C-terminus. The tagged protein demonstrated an important modulation of its expression.

The genomes of Plasmodium parasites that cause malaria in humans, other primates, birds, and rodents all encode multiple 6-cys proteins. Distinct 6-cys protein family members reside on the surface at each extracellular life cycle stage and those on the surface of liver infective and sexual stages have been shown to play important roles in hepatocyte growth and fertilization respectively. However, 6-cys proteins associated with the blood-stage forms of the parasite have no known function. Here we investigate the biochemical nature and function of two blood-stage 6-cys proteins in Plasmodium falciparum, the most pathogenic species to afflict humans. We show that native P12 and P41 form a stable heterodimer on the infective merozoite surface and are secreted following invasion, but could find no evidence that this complex mediates erythrocyte-receptor binding. That P12 and P41 do not appear to have a major role as adhesins to erythrocyte receptors was supported by the observation that antisera to these proteins did not substantially inhibit erythrocyte invasion. To investigate other functional roles for these proteins their genes were successfully disrupted in P. falciparum, however P12 and P41 knockout parasites grew at normal rates in vitro and displayed no other obvious phenotypic changes. It now appears likely that these blood-stage 6-cys proteins operate as a pair and play redundant roles either in erythrocyte invasion or in host-immune interactions.

BACKGROUND: Antibodies targeting blood stage antigens are important in protection against malaria, but the key targets and mechanisms of immunity are not well understood. Merozoite surface protein 1 (MSP1) is an abundant and essential protein. The C-terminal 19 kDa region (MSP1-19) is regarded as a promising vaccine candidate and may also be an important target of immunity. METHODOLOGY/FINDINGS: Growth inhibitory antibodies against asexual-stage parasites and IgG to recombinant MSP1-19 were measured in plasma samples from a longitudinal cohort of 206 children in Papua New Guinea. Differential inhibition by samples of mutant P. falciparum lines that expressed either the P. falciparum or P. chabaudi form of MSP1-19 were used to quantify MSP1-19 specific growth-inhibitory antibodies. The great majority of children had detectable IgG to MSP1-19, and high levels of IgG were significantly associated with a reduced risk of symptomatic P. falciparum malaria during the 6-month follow-up period. However, there was little evidence of PfMSP1-19 specific growth inhibition by plasma samples from children. Similar results were found when testing non-dialysed or dialysed plasma, or purified antibodies, or when measuring growth inhibition in flow cytometry or microscopy-based assays. Rabbit antisera generated by immunization with recombinant MSP1-19 demonstrated strong MSP1-19 specific growth-inhibitory activity, which appeared to be due to much higher antibody levels than human samples; antibody avidity was similar between rabbit antisera and human plasma. CONCLUSIONS/SIGNIFICANCE: These data suggest that MSP1-19 is not a major target of growth inhibitory antibodies and that the protective effects of antibodies to MSP1-19 are not due to growth inhibitory activity, but may instead be mediated by other mechanisms. Alternatively, antibodies to MSP1-19 may act as a marker of protective immunity.

Apicomplexan parasites are obligate intracellular parasites that infect a variety of hosts, causing significant diseases in livestock and humans. The invasive forms of the parasites invade their host cells by gliding motility, an active process driven by parasite adhesion proteins and molecular motors. A crucial point during host cell invasion is the formation of a ring-shaped area of intimate contact between the parasite and the host known as a tight junction. As the invasive zoite propels itself into the host-cell, the junction moves down the length of the parasite. This process must be tightly regulated and signalling is likely to play a role in this event. One crucial protein for tight-junction formation is the apical membrane antigen 1 (AMA1). Here we have investigated the phosphorylation status of this key player in the invasion process in the human malaria parasite Plasmodium falciparum. We show that the cytoplasmic tail of P. falciparum AMA1 is phosphorylated at serine 610. We provide evidence that the enzyme responsible for serine 610 phosphorylation is the cAMP regulated protein kinase A (PfPKA). Importantly, mutation of AMA1 serine 610 to alanine abrogates phosphorylation of AMA1 in vivo and dramatically impedes invasion. In addition to shedding unexpected new light on AMA1 function, this work represents the first time PKA has been implicated in merozoite invasion.

We present Bäcklund transformations for the non-commutative anti-self-dual Yang–Mills equation where the gauge group is G=GL(2), and use it to generate a series of exact solutions from a simple seed solution. The solutions generated by this approach are represented in terms of quasi-determinants. We also explain the origins of all the ingredients of the Bäcklund transformations within the framework of non-commutative twistor theory. In particular, we show that the generated solutions belong to a non-commutative version of the Atiyah–Ward ansatz. [ABSTRACT FROM AUTHOR]

A non-Abelian version of the Hirota-Miwa equation is considered. In an earlier paper of Nimmo (2006 J. Phys. A: Math. Gen. 39 5053-65) it was shown how solutions expressed as quasideterminants could be constructed for this system by means of Darboux transformations. In this paper, we discuss these solutions from a different perspective and show that the solutions are quasi-Plücker coordinates and that the non-Abelian Hirota-Miwa equation may be written as a quasi-Plücker relation. The special case of the matrix Hirota-Miwa equation is also considered using a more traditional, bilinear approach and the techniques are compared. [ABSTRACT FROM AUTHOR]

A noncommutative version of the KP equation and two families of its solutions expressed as quasideterminants are discussed. The origin of these solutions is explained by means of Darboux and binary Darboux transformations. Additionally, it is shown that these solutions may also be verified directly. This approach is reminiscent of the wronskian technique used for the Hirota bilinear form of the regular, commutative KP equation but, in the noncommutative case, no bilinearizing transformation is available. [ABSTRACT FROM AUTHOR]

The deuterium NMR spectra of the ternary metal deuterides (TMDs) Ca2RhD5and Ca2IrD5show that the disorder is dynamic at room temperature, with barriers to the motion of 31.8 and 39.0 kJ mol-1, respectively. At low temperatures, splittings equivalent to quadrupole coupling constants of 50.9 and 24.5 kHz were obtained for Ca2RhD5and 68.3 and 41.7 kHz for Ca2IrD5and are assigned to the planar and apical deuterium positions, respectively. Differential scanning calorimetric study of the transition in Ca2IrH5located a reversible phase transition at 284 K with an enthalpy change of 650 J mol-1and entropy change of 2.3 J K-1mol-1. [ABSTRACT FROM AUTHOR]

Mitochondrial fission requires the division of both the inner and outer mitochondrial membranes. Dynamin-related proteins operate in division of the outer membrane of probably all mitochondria, and also that of chloroplasts - organelles that have a bacterial origin like mitochondria. How the inner mitochondrial membrane divides is less well established. Homologues of the major bacterial division protein, FtsZ, are known to reside inside mitochondria of the chromophyte alga Mallomonas, a red alga, and the slime mould Dictyostelium discoideum, where these proteins are likely to act in division of the organelle. Mitochondrial FtsZ is, however, absent from the genomes of higher eukaryotes (animals, fungi, and plants), even though FtsZs are known to be essential for the division of probably all chloroplasts. To begin to understand why higher eukaryotes have lost mitochondrial FtsZ, we have sampled various diverse protists to determine which groups have retained the gene. Database searches and degenerate PCR uncovered genes for likely mitochondrial FtsZs from the glaucocystophyte Cyanophora paradoxa, the oomycete Phytophthora infestans, two haptophyte algae, and two diatoms - one being Thalassiosira pseudonana, the draft genome of which is now available. From Thalassiosira we also identified two chloroplast FtsZs, one of which appears to be undergoing a C-terminal shortening that may be common to many organellar FtsZs. Our data indicate that many protists still employ the FtsZ-based ancestral mitochondrial division mechanism, and that mitochondrial FtsZ has been lost numerous times in the evolution of eukaryotes. [ABSTRACT FROM AUTHOR]

We solve the direct scattering problem for the ultradiscrete Korteweg de Vries (udKdV) equation, over for any potential with compact (finite) support, by explicitly constructing bound state and non-bound state eigenfunctions. We then show how to reconstruct the potential in the scattering problem at any time, using an ultradiscrete analogue of a Darboux transformation. This is achieved in two steps. First we use so-called 'undressing' transformations (i.e. Darboux transformations that use bound state eigenfunctions) on the potential in the scattering problem to obtain data that uniquely characterises both its soliton content and the remaining 'background', and thereby the entire potential. Then we use so-called 'dressing' transformations (i.e. Darboux transformations that use bound state eigenfunctions) to put back the solitonic content in the background at general time t, whereby obtaining an explicit expression for the solution to the udKdV equation associated to the original potential at t  =  0. [ABSTRACT FROM AUTHOR]

The modern field of optical angular momentum began with the realisation by Allen et al in 1992 that, in addition to the spin associated with polarisation, light beams with helical phase fronts carry orbital angular momentum. There has been much confusion and debate, however, surrounding the intricacies of the field and, in particular, the separation of the angular momentum into its spin and orbital parts. Here we take the opportunity to state the current position as we understand it, which we present as six perspectives: (i) we start with a reprise of the 1992 paper in which it was pointed out that the Laguerre–Gaussian modes, familiar from laser physics, carry orbital angular momentum. (ii) The total angular momentum may be separated into spin and orbital parts, but neither alone is a true angular momentum. (iii) The spin and orbital parts, although not themselves true angular momenta, are distinct and physically meaningful, as has been demonstrated clearly in a range of experiments. (iv) The orbital part of the angular momentum in the direction of propagation of a beam is not simply the azimuthal component of the linear momentum. (v) The component of spin in the direction of propagation is not the helicity, although these are related quantities. (vi) Finally, the spin and orbital parts of the angular momentum correspond to distinct symmetries of the free electromagnetic field and hence are separately conserved quantities. [ABSTRACT FROM AUTHOR]

The usual description in basic electromagnetic theory of the linear and angular momenta of light is centred upon the identification of Poynting's vector as the linear momentum density and its cross product with position, or azimuthal component, as the angular momentum density. This seemingly reasonable approach brings with it peculiarities, however, in particular with regards to the separation of angular momentum into orbital and spin contributions, which has sometimes been regarded as contrived. In the present paper, we observe that densities are not unique, which leads us to ask whether the usual description is, in fact, the most natural choice. To answer this, we adopt a fundamental rather than heuristic approach by first identifying appropriate symmetries of Maxwell's equations and subsequently applying Noether's theorem to obtain associated conservation laws. We do not arrive at the usual description. Rather, an equally acceptable one in which the relationship between linear and angular momenta is nevertheless more subtle and in which orbital and spin contributions emerge separately and with transparent forms. [ABSTRACT FROM AUTHOR]

A generalization of the ultra-discrete KdV equation is investigated using a direct approach. We show that evolution through one time step serves to reveal the entire solitonic content of the system. [ABSTRACT FROM AUTHOR]

We consider a noncommutative version of the Davey-Stewartson equations and derive two families of quasideterminant solution via Darboux and binary Darboux transformations. These solutions can be verified by direct substitution. We then calculate the dromion solutions of the equations and obtain computer plots in a noncommutative setting. [ABSTRACT FROM AUTHOR]

A noncommutative version of the modified KP equation and a family of its solutions expressed as quasideterminants are discussed. The origin of these solutions is explained by means of Darboux transformations and the solutions are verified directly. We also verify directly an explicit connection between quasideterminant solutions of the noncommutative mKP equation and the noncommutative KP equation arising from the Miura transformation. [ABSTRACT FROM AUTHOR]

Background: The emergence of SARS-CoV-2 variants and COVID-19 vaccination have resulted in complex exposure histories. Rapid assessment of the effects of these exposures on neutralising antibodies against SARS-CoV-2 infection is crucial for informing vaccine strategy and epidemic management. We aimed to investigate heterogeneity in individual-level and population-level antibody kinetics to emerging variants by previous SARS-CoV-2 exposure history, to examine implications for real-time estimation, and to examine the effects of vaccine-campaign timing., Methods: Our Bayesian hierarchical model of antibody kinetics estimated neutralising-antibody trajectories against a panel of SARS-CoV-2 variants quantified with a live virus microneutralisation assay and informed by individual-level COVID-19 vaccination and SARS-CoV-2 infection histories. Antibody titre trajectories were modelled with a piecewise linear function that depended on the key biological quantities of an initial titre value, time the peak titre is reached, set-point time, and corresponding rates of increase and decrease for gradients between two timing parameters. All process parameters were estimated at both the individual level and the population level. We analysed data from participants in the University College London Hospitals-Francis Crick Institute Legacy study cohort (NCT04750356) who underwent surveillance for SARS-CoV-2 either through asymptomatic mandatory occupational health screening once per week between April 1, 2020, and May 31, 2022, or symptom-based testing between April 1, 2020, and Feb 1, 2023. People included in the Legacy study were either Crick employees or health-care workers at three London hospitals, older than 18 years, and gave written informed consent. Legacy excluded people who were unable or unwilling to give informed consent and those not employed by a qualifying institution. We segmented data to include vaccination events occurring up to 150 days before the emergence of three variants of concern: delta, BA.2, and XBB 1.5. We split the data for each wave into two categories: real-time and retrospective. The real-time dataset contained neutralising-antibody titres collected up to the date of emergence in each wave; the retrospective dataset contained all samples until the next SARS-CoV-2 exposure of each individual, whether vaccination or infection., Findings: We included data from 335 participants in the delta wave analysis, 223 (67%) of whom were female and 112 (33%) of whom were male (median age 40 years, IQR 22-58); data from 385 participants in the BA.2 wave analysis, 271 (70%) of whom were female and 114 (30%) of whom were male (41 years, 22-60); and data from 248 participants in the XBB 1.5 wave analysis, 191 (77%) of whom were female, 56 (23%) of whom were male, and one (<1%) of whom preferred not to say (40 years, 21-59). Overall, we included 968 exposures (vaccinations) across 1895 serum samples in the model. For the delta wave, we estimated peak titre values as 490·0 IC 50 (95% credible interval 224·3-1515·9) for people with no previous infection and as 702·4 IC 50 (300·8-2322·7) for people with a previous infection before omicron; the delta wave did not include people with a previous omicron infection. For the BA.2 wave, we estimated peak titre values as 858·1 IC 50 (689·8-1363·2) for people with no previous infection, 1020·7 IC 50 (725·9-1722·6) for people with a previous infection before omicron, and 1422·0 IC 50 (679·2-3027·3) for people with a previous omicron infection. For the XBB 1.5 wave, we estimated peak titre values as 703·2 IC 50 (415·0-3197·8) for people with no previous infection, 1215·9 IC 50 (511·6-7338·7) for people with a previous infection before omicron, and 1556·3 IC 50 (757·2-7907·9) for people with a previous omicron infection., Interpretation: Our study shows the feasibility of real-time estimation of antibody kinetics before SARS-CoV-2 variant emergence. This estimation is valuable for understanding how specific combinations of SARS-CoV-2 exposures influence antibody kinetics and for examining how COVID-19 vaccination-campaign timing could affect population-level immunity to emerging variants., Funding: Wellcome Trust, National Institute for Health Research University College London Hospitals Biomedical Research Centre, UK Research and Innovation, UK Medical Research Council, Francis Crick Institute, and Genotype-to-Phenotype National Virology Consortium., Competing Interests: Declaration of interests CSw receives grants from Bristol Myers Squibb, Ono Pharmaceuticals, Boehringer Ingelheim, Roche-Ventana, Pfizer, and Archer Dx; receives personal fees from Genentech, the Sarah Canon Research Institute, Medicxi, Bicycle Therapeutics, GRAIL, Amgen, AstraZeneca, Bristol Myers Squibb, Illumina, GlaxoSmithKline, MSD, and Roche-Ventana; holds stock options in Apogen Biotech, Epic Biosciences, GRAIL, and Achilles Therapeutics; is a member of a scientific advisory board for Bicycle Therapeutics, GRAIL, Relay Therapeutics, SAGA Diagnostics, and Achilles Therapeutics; is a co-founder of Achilles Therapeutics; receives consulting fees from Genentech, Medicxi, MetaboMed, Novartis, the China Innovation Centre of Roche, and the Sarah Cannon Research Institute; and receives honoraria from Amgen, AstraZeneca, Bristol Myers Squibb, Illumina, and Incyte. DLVB receives grants, paid to their institution, from AstraZeneca. EJC is an unpaid member of the Infection, Prevention and Control Committee of the UK Kidney Association. RB and DLVB are members of the Genotype-to-Phenotype 2 Consortium. AJK received the Sir Henry Dale Fellowship, jointly funded by the Wellcome Trust and the Royal Society (grant number 206250/Z/17/Z). AJK and DH were supported by the National Institutes of Health (1R01AI141534–01A1). All other authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Background: Over the past three decades, our understanding of sleep apnea in women has advanced, revealing disparities in pathophysiology, diagnosis, and treatment compared to men. However, no real-life study to date has explored the relationship between mask-related side effects (MRSEs) and gender in the context of long-term CPAP., Methods: The InterfaceVent-CPAP study is a prospective real-life cross-sectional study conducted in an apneic adult cohort undergoing at least 3 months of CPAP with unrestricted mask-access (34 different masks, no gender specific mask series). MRSE were assessed by the patient using visual analog scales (VAS). CPAP-non-adherence was defined as a mean CPAP-usage of less than 4 h per day. The primary objective of this ancillary study was to investigate the impact of gender on the prevalence of MRSEs reported by the patient. Secondary analyses assessed the impact of MRSEs on CPAP-usage and CPAP-non-adherence depending on the gender., Results: A total of 1484 patients treated for a median duration of 4.4 years (IQ 25-75 : 2.0-9.7) were included in the cohort, with women accounting for 27.8%. The prevalence of patient-reported mask injury, defined as a VAS score ≥ 5 (p = 0.021), was higher in women than in men (9.6% versus 5.3%). For nasal pillow masks, the median MRSE VAS score for dry mouth was higher in women (p = 0.039). For oronasal masks, the median MRSE VAS score for runny nose was higher in men (p = 0.039). Multivariable regression analyses revealed that, for both women and men, dry mouth was independently and negatively associated with CPAP-usage, and positively associated with CPAP-non-adherence., Conclusion: In real-life patients treated with long-term CPAP, there are gender differences in patient reported MRSEs. In the context of personalized medicine, these results suggest that the design of future masks should consider these gender differences if masks specifically for women are developed. However, only dry mouth, a side effect not related to mask design, impacts CPAP-usage and non-adherence., Trial Registration: INTERFACEVENT IS REGISTERED WITH CLINICALTRIALS.GOV (NCT03013283).FIRST REGISTRATION DATE IS 2016-12-23., (© 2024. The Author(s).)

Cellular senescence, a stress-induced stable proliferation arrest associated with an inflammatory senescence-associated secretory phenotype (SASP), is a cause of aging. In senescent cells, cytoplasmic chromatin fragments (CCFs) activate SASP via the anti-viral cGAS/STING pathway. Promyelocytic leukemia (PML) protein organizes PML nuclear bodies (NBs), which are also involved in senescence and anti-viral immunity. The HIRA histone H3.3 chaperone localizes to PML NBs in senescent cells. Here, we show that HIRA and PML are essential for SASP expression, tightly linked to HIRA's localization to PML NBs. Inactivation of HIRA does not directly block expression of nuclear factor κB (NF-κB) target genes. Instead, an H3.3-independent HIRA function activates SASP through a CCF-cGAS-STING-TBK1-NF-κB pathway. HIRA physically interacts with p62/SQSTM1, an autophagy regulator and negative SASP regulator. HIRA and p62 co-localize in PML NBs, linked to their antagonistic regulation of SASP, with PML NBs controlling their spatial configuration. These results outline a role for HIRA and PML in the regulation of SASP., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objective: Metabolic dysfunction associated fatty liver disease (MAFLD) is over-represented in people with HIV (PWH). Maraviroc (MVC) and/or metformin (MET) may reduce MAFLD by influencing inflammatory pathways and fatty acid metabolism., Design: Open-label, 48-week randomized trial with a 2 x 2 factorial design., Setting: Multicenter HIV clinics., Participants: Nondiabetic, virologically suppressed PLWH, aged at least 35 years, with confirmed/suspected MAFLD (≥1 biochemical/anthropometric/radiological/histological features)., Intervention: Adjunctive MVC; MET; MVC+MET vs. antiretroviral therapy (ART) alone., Primary Outcome: Change in liver fat fraction (LFF) between baseline and week-48 using magnetic resonance proton density fat fraction (MR PDFF)., Results: Six sites enrolled 90 participants (93% male; 81% white; median age 52 [interquartile range, IQR 47-57] years) between March 19, 2018, and November 11, 2019. Seventy percent had imaging/biopsy and at least one 1 MAFLD criteria. The analysis included 82/90 with week-0 and week-48 scans. Median baseline MR PDFF was 8.9 (4.6-17.1); 40, 38, 8, and 14% had grade zero, one, two, and three steatosis, respectively. Mean LFF increased slightly between baseline and follow-up scans: 2.22% MVC, 1.26% MET, 0.81% MVC+MET, and 1.39% ART alone. Prolonged intervention exposure (delayed week-48 scans) exhibited greater increases in MR PDFF (estimated difference 4.23% [95% confidence interval, 95% CI 2.97-5.48], P  < 0.001). There were no differences in predicted change for any intervention compared to ART alone: MVC (-0.42% [95% CI -1.53 to 0.68, P  = 0.45]), MET (-0.62 [-1.81 to 0.56, P  = 0.30]), and MVC+MET (-1.04 [-2.74 to 0.65, P  = 0.23]). Steatosis grade remained unchanged in 55% and increased in 24%., Conclusion: Baseline levels of liver fat were lower than predicted. Contrary to our hypothesis, neither MVC, MET, or the combination significantly reduced liver fat as measured by MRPDFF compared to ART alone., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Cellular senescence, a stress-induced stable proliferation arrest associated with an inflammatory Senescence-Associated Secretory Phenotype (SASP), is a cause of aging. In senescent cells, Cytoplasmic Chromatin Fragments (CCFs) activate SASP via the anti-viral cGAS/STING pathway. PML protein organizes PML nuclear bodies (NBs), also involved in senescence and anti-viral immunity. The HIRA histone H3.3 chaperone localizes to PML NBs in senescent cells. Here, we show that HIRA and PML are essential for SASP expression, tightly linked to HIRA's localization to PML NBs. Inactivation of HIRA does not directly block expression of NF-κB target genes. Instead, an H3.3-independent HIRA function activates SASP through a CCF-cGAS-STING-TBK1-NF-κB pathway. HIRA physically interacts with p62/SQSTM1, an autophagy regulator and negative SASP regulator. HIRA and p62 co-localize in PML NBs, linked to their antagonistic regulation of SASP, with PML NBs controlling their spatial configuration. These results outline a role for HIRA and PML in regulation of SASP.

Background: SARS-CoV-2 variant Omicron rapidly evolved over 2022, causing three waves of infection due to sub-variants BA.1, BA.2 and BA.4/5. We sought to characterise symptoms and viral loads over the course of COVID-19 infection with these sub-variants in otherwise-healthy, vaccinated, non-hospitalised adults, and compared data to infections with the preceding Delta variant of concern (VOC)., Methods: In a prospective, observational cohort study, healthy vaccinated UK adults who reported a positive polymerase chain reaction (PCR) or lateral flow test, self-swabbed on alternate weekdays until day 10. We compared participant-reported symptoms and viral load trajectories between infections caused by VOCs Delta and Omicron (sub-variants BA.1, BA.2 or BA.4/5), and tested for relationships between vaccine dose, symptoms and PCR cycle threshold (Ct) as a proxy for viral load using Chi-squared (χ2) and Wilcoxon tests., Results: 563 infection episodes were reported among 491 participants. Across infection episodes, there was little variation in symptom burden (4 [IQR 3-5] symptoms) and duration (8 [IQR 6-11] days). Whilst symptom profiles differed among infections caused by Delta compared to Omicron sub-variants, symptom profiles were similar between Omicron sub-variants. Anosmia was reported more frequently in Delta infections after 2 doses compared with Omicron sub-variant infections after 3 doses, for example: 42% (25/60) of participants with Delta infection compared to 9% (6/67) with Omicron BA.4/5 (χ2 P < 0.001; OR 7.3 [95% CI 2.7-19.4]). Fever was less common with Delta (20/60 participants; 33%) than Omicron BA.4/5 (39/67; 58%; χ2 P = 0.008; OR 0.4 [CI 0.2-0.7]). Amongst infections with an Omicron sub-variants, symptoms of coryza, fatigue, cough and myalgia predominated. Viral load trajectories and peaks did not differ between Delta, and Omicron, irrespective of symptom severity (including asymptomatic participants), VOC or vaccination status. PCR Ct values were negatively associated with time since vaccination in participants infected with BA.1 (β = -0.05 (CI -0.10-0.01); P = 0.031); however, this trend was not observed in BA.2 or BA.4/5 infections., Conclusion: Our study emphasises both the changing symptom profile of COVID-19 infections in the Omicron era, and ongoing transmission risk of Omicron sub-variants in vaccinated adults., Trial Registration: NCT04750356., Competing Interests: CSw reports interests unrelated to this Correspondence: grants from BMS, Ono-Pharmaceuticals, Boehringer-Ingelheim, Roche-Ventana, Pfizer and Archer Dx, unrelated to this Correspondence; personal fees from Genentech, Sarah Canon Research Institute, Medicxi, Bicycle Therapeutics, GRAIL, Amgen, AstraZeneca, BMS, Illumina, GlaxoSmithKline, MSD, and Roche-Ventana, unrelated to this Correspondence; and stock options from Apogen Biotech, Epic Biosciences, GRAIL, and Achilles Therapeutics, unrelated to this Correspondence. DLVB reports grants from AstraZeneca unrelated to this Correspondence. All other authors declare no competing interests. This declaration on competing interests does not alter our adherence to PLOS ONE policies on sharing data and materials, (Copyright: © 2024 Townsley et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Objective: Bone loss in people with HIV (PWH) is poorly understood. Switching tenofovir disoproxil fumarate (TDF) to tenofovir alafenamide (TAF) has yielded bone mineral density (BMD) increases. PETRAM (NCT#:03405012) investigated whether BMD and bone turnover changes correlate., Design: Open-label, randomized controlled trial., Setting: Single-site, outpatient, secondary care., Participants: Nonosteoporotic, virologically suppressed, cis-male PWH taking TDF/emtricitabine (FTC)/rilpivirine (RPV) for more than 24 weeks., Intervention: Continuing TDF/FTC/RPV versus switching to TAF/FTC/RPV (1 : 1 randomization)., Main Outcome Measures: :[ 18 F]NaF-PET/CT for bone turnover (standardized uptake values, SUV mean ) and dual-energy x-ray absorptiometry for lumbar spine and total hip BMD., Results: Thirty-two men, median age 51 years, 76% white, median duration TDF/FTC/RPV 49 months, were randomized between 31 August 2018 and 09 March 2020. Sixteen TAF:11 TDF were analyzed. Baseline-final scan range was 23-103 (median 55) weeks. LS-SUV mean decreased for both groups (TAF -7.9% [95% confidence interval -14.4, -1.5], TDF -5.3% [-12.1,1.5], P  = 0.57). TH-SUV mean showed minimal changes (TAF +0.3% [-12.2,12.8], TDF +2.9% [-11.1,16.9], P  = 0.77). LS-BMD changes were slightly more favorable with TAF but failed to reach significance (TAF +1.7% [0.3,3.1], TDF -0.3 [-1.8,1.2], P  = 0.06). Bone turnover markers decreased more with TAF ([CTX -35.3% [-45.7, -24.9], P1NP -17.6% [-26.2, -8.5]) than TDF (-11.6% [-28.8, +5.6] and -6.9% [-19.2, +5.4] respectively); statistical significance was only observed for CTX ( P  = 0.02, P1NP, P  = 0.17)., Conclusion: Contrary to our hypothesis, lumbar spine and total hip regional bone formation (SUV mean ) and BMD did not differ postswitch to TAF. However, improved LS-BMD and CTX echo other TAF-switch studies. The lack of difference in SUV mean may be due to inadequate power., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)

Purpose of Review: The 2022 global outbreak of mpox disproportionally affected people with HIV (PWH). We review the data on the presentation, treatment, and prevention of mpox in PWH., Recent Findings: Most PWH with mpox had a mild and self-limiting illness, no different to people without HIV. A higher rate of rectal symptoms has been reported among PWH and those with advanced HIV disease were at higher risk of severe disease, hospitalization, and death. Treatment with antivirals was widely used in hospitalized patients without any randomized control trial data to support its use and without any data specifically in PWH. Use of smallpox vaccines to prevent mpox is safe in PWH regardless of CD4+ cell count. There is limited data on efficacy in those with lower CD4+ cell count and on long-term protective efficacy., Summary: PWH should be offered vaccination against mpox in line with national guidelines. PWH should be individually risk-assessed for severe mpox, based on their CD4+ cell count and co-morbidities and ideally recruited into treatment trials to build an evidence base on efficacy. HIV and other sexually transmitted infection testing should be offered to all people diagnosed with mpox., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Hepatic steatosis is a major cause of chronic liver disease associated with several negative health outcomes. We compared the prevalence of and factors associated with steatosis in people living with and without HIV., Methods: Older (>50 years) and younger (<50 years) people with HIV and older HIV-negative controls (>50 years) underwent liver transient elastography examination with controlled attenuation parameter (steatosis ≥238 dB/m, moderate/severe steatosis ≥280 dB/m, liver fibrosis ≥7.1 kPa). We compared groups using logistic regression/Chi-squared/Fisher's exact/Kruskal-Wallis tests., Results: In total, 317 participants (109 older people with HIV; 101 younger people with HIV; 107 HIV-negative controls) were predominantly white (86%) and male (76%), and 21% were living with obesity (body mass index ≥30 kg/m 2 ). Most (97%) people with HIV had undetectable HIV RNA. The prevalence of fibrosis was 8.4%, 3.0%, and 6.5% in the three groups, respectively (p = 0.26). Fibrosis was predominately (>65%) mild. The prevalence of steatosis was the same in older people with HIV (66.4%) and controls (66.4%) but lower in younger people with HIV (37.4%; p < 0.001). After adjustment, younger people with HIV were less likely to have steatosis (odds ratio [OR] 0.26; 95% confidence interval [CI] 0.14-0.52) than controls, but male sex (OR 2.45; 95% CI 1.20-4.50) and high waist-to-hip ratio (OR 3.04; 95% CI 1.74-5.33) were associated with an increased odds of steatosis. We found no association between steatosis and HIV-related variables., Conclusions: The prevalence of hepatic steatosis and fibrosis was similar between older participants regardless of HIV status. Age, sex, and abdominal obesity, but not HIV-related variables, were associated with steatosis. Interventions for controlling obesity should be integrated into routine HIV care., (© 2023 The Authors. HIV Medicine published by John Wiley & Sons Ltd on behalf of British HIV Association.)

Leakage is a common issue with PAP therapy and may contribute to short-term non-compliance with treatment. PAP manufacturers use different methods to estimate and report air leaks (median, mean, p90, p95, % of important air leak, time spent on major leaks), which makes the analysis and comparisons challenging. Leak intensity is a well-known parameter of major importance as it can significantly affect the performance of PAP devices. However, there is a lack of knowledge regarding another leakage parameter, namely the leakage pattern. As of now, there is no standard classification for leak patterns in real-life settings. Our objective was to develop and propose a comprehensive nomenclature for leakage patterns observed during nasal auto-PAP therapy. We examined 50 ventilatory polygraphy recordings conducted with auto-PAP, based on data from a prior study in which the unintentional leak flow was precisely measured over time. We have categorized leaks into two main types: continuous leaks, which appear and persist for an extended period, and discontinuous leaks, which vanish more rapidly. Continuous leaks can have both abrupt or gradual apparitions and terminations. Their "shape" can be either interrupted or constant. Discontinuous leaks can have both abrupt or gradual apparitions and terminations. Due to the relatively short observation scale (less than 5 min minutes), this type of leakage is not characterized by a specific shape between apparition and termination. This nomenclature could be a valuable tool that facilitates comparative bench tests or clinical studies. This tool could support manufacturers in developing precise algorithms for leak compensation, residual AHI estimation and the accuracy of CPAP monitoring data. Lastly, establishing a standardized approach for describing and categorizing air leakage patterns could assist clinicians in identifying device-related issues, such as patient discomfort arising from specific types of leakage., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Lebret Marius reports a relationship with Air Liquide Medical Systems and KerNel Biomedical that includes: employment., (Copyright © 2023. Published by Elsevier B.V.)