Autoantibodies inhibit Plasmodium falciparum growth and are associated with protection from clinical malaria.

Many infections, including malaria, are associated with an increase in autoantibodies (AAbs). Prior studies have reported an association between genetic markers of susceptibility to autoimmune disease and resistance to malaria, but the underlying mechanisms are unclear. Here, we performed a longitudinal study of children and adults (n = 602) in Mali and found that high levels of plasma AAbs before the malaria season independently predicted a reduced risk of clinical malaria in children during the ensuing malaria season.

APEX2-based proximity proteomic analysis identifies candidate interactors for Plasmodium falciparum knob-associated histidine-rich protein in infected erythrocytes.

The interaction of Plasmodium falciparum-infected red blood cells (iRBCs) with the vascular endothelium plays a crucial role in malaria pathology and disease. KAHRP is an exported P. falciparum protein involved in iRBC remodelling, which is essential for the formation of protrusions or "knobs" on the iRBC surface.

Application of B cell immortalization for the isolation of antibodies and B cell clones from vaccine and infection settings.

The isolation and characterization of neutralizing antibodies from infection and vaccine settings informs future vaccine design, and methodologies that streamline the isolation of antibodies and the generation of B cell clones are of great interest. Retroviral transduction to express Bcl-6 and Bcl-xL and transform primary B cells has been shown to promote long-term B cell survival and antibody secretion , and can be used to isolate antibodies from memory B cells. However, application of this methodology to B cell subsets from different tissues and B cells from chronically infected individuals has not been well characterized.

Neutralizing and interfering human antibodies define the structural and mechanistic basis for antigenic diversion.

Defining mechanisms of pathogen immune evasion and neutralization are critical to develop potent vaccines and therapies. Merozoite Surface Protein 1 (MSP-1) is a malaria vaccine antigen and antibodies to MSP-1 are associated with protection from disease. However, MSP-1-based vaccines performed poorly in clinical trials in part due to a limited understanding of the protective antibody response to MSP-1 and of immune evasion by antigenic diversion.

Assessment of Plasmodium falciparum Antigen-Specific B Cells.

This protocol describes methods that exploit the specificity of binding between the B cell receptor and cognate antigen to detect and characterize Plasmodium-specific human B cells. Importantly, this approach allows for the isolation and study of B cells without activating the cells or requiring them to secrete antibodies. The protocol describes how antigen "probes" are generated and used in flow cytometry to identify and sort antigen-specific B cells, and includes methods for enrichment of antigen-specific B cells prior to flow cytometry.

Comparative intravital imaging of human and rodent malaria sporozoites reveals the skin is not a species-specific barrier.

Malaria infection starts with the injection of Plasmodium sporozoites into the host's skin. Sporozoites are motile and move in the skin to find and enter blood vessels to be carried to the liver. Here, we present the first characterization of P.

Increased circulation time of Plasmodium falciparum underlies persistent asymptomatic infection in the dry season.

The dry season is a major challenge for Plasmodium falciparum parasites in many malaria endemic regions, where water availability limits mosquito vectors to only part of the year. How P. falciparum bridges two transmission seasons months apart, without being cleared by the human host or compromising host survival, is poorly understood.

Generation of Transmission-Competent Human Malaria Parasites with Chromosomally-Integrated Fluorescent Reporters.

Malaria parasites have a complex life cycle that includes specialized stages for transmission between their mosquito and human hosts. These stages are an understudied part of the lifecycle yet targeting them is an essential component of the effort to shrink the malaria map. The human parasite Plasmodium falciparum is responsible for the majority of deaths due to malaria.

Antibody-Mediated Protection against Sporozoites Begins at the Dermal Inoculation Site.

sporozoites are injected into the skin as mosquitoes probe for blood. From here, they migrate through the dermis to find blood vessels which they enter in order to be rapidly carried to the liver, where they invade hepatocytes and develop into the next life cycle stage, the exoerythrocytic stage. Once sporozoites enter the blood circulation, they are found in hepatocytes within minutes.

Alpha-v-containing integrins are host receptors for the sporozoite surface protein, TRAP.

Malaria-causing sporozoites are deposited in the dermis by the bite of an infected mosquito and move by gliding motility to the liver where they invade and develop within host hepatocytes. Although extracellular interactions between sporozoite ligands and host receptors provide important guidance cues for productive infection and are good vaccine targets, these interactions remain largely uncharacterized. Thrombospondin-related anonymous protein (TRAP) is a parasite cell surface ligand that is essential for both gliding motility and invasion because it couples the extracellular binding of host receptors to the parasite cytoplasmic actinomyosin motor; however, the molecular nature of the host TRAP receptors is poorly defined.

Discovery of Plasmodium (M)TRAP-Aldolase Interaction Stabilizers Interfering with Sporozoite Motility and Invasion.

As obligate, intracellular parasites, Plasmodium spp. rely on invasion of host cells in order to replicate and continue their life cycle. The parasite needs to traverse the dermis and endothelium of blood vessels, invade hepatocytes and red blood cells, traverse the mosquito midgut, and enter the salivary glands to continue the cycle of infection and transmission.

Deletion of the rodent malaria ortholog for falcipain-1 highlights differences between hepatic and blood stage merozoites.

Proteases have been implicated in a variety of developmental processes during the malaria parasite lifecycle. In particular, invasion and egress of the parasite from the infected hepatocyte and erythrocyte, critically depend on protease activity. Although falcipain-1 was the first cysteine protease to be characterized in P.

Palmitoyl transferases have critical roles in the development of mosquito and liver stages of Plasmodium.

As the Plasmodium parasite transitions between mammalian and mosquito host, it has to adjust quickly to new environments. Palmitoylation, a reversible and dynamic lipid post-translational modification, plays a central role in regulating this process and has been implicated with functions for parasite morphology, motility and host cell invasion. While proteins associated with the gliding motility machinery have been described to be palmitoylated, no palmitoyl transferase responsible for regulating gliding motility has previously been identified.

Longitudinal analysis of Plasmodium sporozoite motility in the dermis reveals component of blood vessel recognition.

Malaria infection starts with injection of Plasmodium sporozoites by an Anopheles mosquito into the skin of the mammalian host. How sporozoites locate and enter a blood vessel is a critical, but poorly understood process. In this study, we examine sporozoite motility and their interaction with dermal blood vessels, using intravital microscopy in mice.

Phosphoproteomics reveals malaria parasite Protein Kinase G as a signalling hub regulating egress and invasion.

Our understanding of the key phosphorylation-dependent signalling pathways in the human malaria parasite, Plasmodium falciparum, remains rudimentary. Here we address this issue for the essential cGMP-dependent protein kinase, PfPKG. By employing chemical and genetic tools in combination with quantitative global phosphoproteomics, we identify the phosphorylation sites on 69 proteins that are direct or indirect cellular targets for PfPKG.

The innate and adaptive response to mosquito saliva and Plasmodium sporozoites in the skin.

A malaria infection begins when an infected mosquito takes a blood meal and inoculates parasites into the skin of its mammalian host. The parasite then has to exit the skin and escape the immune cells that protect the body from infection and alert the system to intruding pathogens. It has become apparent that this earliest stage of infection is amenable to vaccine interventions.

The repeat region of the circumsporozoite protein is critical for sporozoite formation and maturation in Plasmodium.

The circumsporozoite protein (CSP) is the major surface protein of the sporozoite stage of malaria parasites and has multiple functions as the parasite develops and then migrates from the mosquito midgut to the mammalian liver. The overall structure of CSP is conserved among Plasmodium species, consisting of a species-specific central tandem repeat region flanked by two conserved domains: the NH2-terminus and the thrombospondin repeat (TSR) at the COOH-terminus. Although the central repeat region is an immunodominant B-cell epitope and the basis of the only candidate malaria vaccine in Phase III clinical trials, little is known about its functional role(s).

Targeting Plasmodium falciparum protein kinases with adenosine analogue-oligoarginine conjugates.

During the last decade, a vast number of inhibitors, ligands and fluorescent probes have evolved for mammalian protein kinases; however, the suitability of these compounds for studies of evolutionarily divergent eukaryotes has mostly been left beyond the scope of research. Here, we examined whether adenosine analogue-oligoarginine conjugates that had been extensively characterized as efficient inhibitors of the human protein kinases are applicable for targeting Plasmodium protein kinases. We demonstrated that ARCs were not only able to bind to and inhibit a representative member of Plasmodium falciparum kinome (cGMP-dependent protein kinase) in biochemical assay, but also affected the general phosphorylation levels in parasites released from the infected red blood cells upon saponin treatment.

Spatiotemporal and functional characterisation of the Plasmodium falciparum cGMP-dependent protein kinase.

Signalling by 3'-5'-cyclic guanosine monophosphate (cGMP) exists in virtually all eukaryotes. In the apicomplexan parasite Plasmodium, the cGMP-dependent protein kinase (PKG) has previously been reported to play a critical role in four key stages of the life cycle. The Plasmodium falciparum isoform (PfPKG) is essential for the initiation of gametogenesis and for blood stage schizont rupture and work on the orthologue from the rodent malaria parasite P.

The role of cGMP signalling in regulating life cycle progression of Plasmodium.

The 3'-5'-cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG) is the main mediator of cGMP signalling in the malaria parasite. This article reviews the role of PKG in Plasmodium falciparum during gametogenesis and blood stage schizont rupture, as well as the role of the Plasmodium berghei orthologue in ookinete differentiation and motility, and liver stage schizont development. The current views on potential effector proteins downstream of PKG and the mechanisms that may regulate cyclic nucleotide levels are presented.

Live imaging of mitosomes and hydrogenosomes by HaloTag technology.

Hydrogenosomes and mitosomes represent remarkable mitochondrial adaptations in the anaerobic parasitic protists such as Trichomonas vaginalis and Giardia intestinalis, respectively. In order to provide a tool to study these organelles in the live cells, the HaloTag was fused to G. intestinalis IscU and T.