Biology subjects

Vlachou, D.

Publications and source records attributed to Vlachou, D..

11 recordsLinked to original sources

bioRxiv2026

Plasmodium Protein Kinase 2 is required for ookinete to oocyst transition, and parasite transmission by the mosquito.

Plasmodium spp., the parasites that are the causative agents of malaria, encode a repertoire of divergent protein kinases that coordinate essential processes including cell division and host cell invasion, yet the functions of many kinases are poorly defined. Plasmodium Protein Kinase 2 (PK2) is essential for asexual blood-stage proliferation and has been implicated in P. falciparum merozoite invasion of red blood cells. However, its role in the sexual stages of the Plasmodium life cycle responsible for transmission is unknown. Here, using live cell imaging, functional analyses, ultrastructure microscopy and phosphoproteomics, we demonstrate that PK2 has a significant role in the Plasmodium berghei life cycle in the mosquito. We show that PK2 is expressed in merozoites, ookinetes and sporozoites - the invasive stages of the parasite life cycle. A conditional knockdown approach revealed that PK2 is required for the ookinete to oocyst transition in the mosquito midgut, potentially associated with altered microneme positioning. Using haemocoel injection to bypass the midgut barrier revealed that PK2 is also required for sporozoite development after midgut invasion. Following PK2 knockdown, global proteome abundance was largely unaffected at 24 h post activation, whereas phosphoproteomics identified changes in phosphorylation of proteins linked to midgut traversal, parasite architecture, and gene regulation. These studies provide insight into the importance of PK2 function in Plasmodium sexual stages and parasite transmission through the mosquito, highlighting its essential function during the three invasive stages of the parasites life cycle.

microbiology↗

bioRxiv2026

A robust negative association between estimated tumour circadian clock function and survival in early stage breast cancer

Recent studies have established that the circadian clock influences onset, progression and therapeutic outcomes in a number of chronic conditions including cardio-metabolic diseases and cancer. For the latter, they also suggest that chronotherapy offers the potential to refine current treatments and improve the development of future anti-cancer medicines. Therefore, there is a need for tools to measure the functional state of the tumoural circadian clock in patients. We have previously developed a model-led machine-learning algorithm called TimeTeller which has the potential to provide such a tool. Here we demonstrate its potential for clinical relevance by a study of 1286 breast cancer patients in which we characterise the nature of the circadian clock disruption in their tumours and demonstrate a strong nonlinear association between 10-year survival and TimeTellers tumoural clock disfunction score {Theta}. We find that good tumour clock function is antagonistic to survival.

cancer biology↗

bioRxiv2025

Metabolic reprogramming and gut microbiota ecology drive divergent Plasmodium vivax infection outcomes in Anopheles darlingi

Anopheles darlingi is the principal malaria vector in the Amazon basin, where Plasmodium vivax accounts for the majority of cases. Despite its epidemiological importance, the molecular and microbial determinants of A. darlingi susceptibility to P. vivax remain poorly understood. Here, we investigated vector-parasite-microbiota interactions using experimental infections with field-derived P. vivax gametocytaemic blood, which produced two distinct infection phenotypes: low and high oocyst burdens. Transcriptomic profiling of mosquito midguts across key parasite developmental timepoints revealed that low-infection mosquitoes mounted an early and sustained response characterised by activation of detoxification pathways, redox regulation, aromatic amino acid catabolism, and purine depletion, likely coordinated through neurophysiological cues, which collectively create a metabolically restrictive environment for parasite development. These physiological changes were accompanied by reduced bacterial diversity and enrichment of Enterobacteriales and Pseudomonadales, taxa previously linked to anti-Plasmodium activity. Conversely, high-infection mosquitoes exhibited limited metabolic reprogramming, expansion of Flavobacteriales, and transcriptional signatures consistent with permissive physiological states, potentially associated with reproductive trade-offs. Importantly, low infection outcomes consistently arose from bloodmeals with the lowest gametocyte densities, suggesting that host- and parasite-derived components of the bloodmeal act as early conditioning factors that prime the mosquito midgut for either resistance or susceptibility. These findings reframe A. darlingi vector competence to P. vivax not as a fixed immune trait but as a dynamic outcome of early redox, metabolic, and microbial interactions. They also highlight ecological and physiological targets for transmission-blocking strategies and reinforce the importance of studying vector-parasite interactions in regionally relevant systems.

molecular biology↗

bioRxiv2025

The nanosd integral gene drive enables population modification of the malaria vector Anopheles gambiae

The modification of mosquito populations at scale through CRISPR-Cas9-mediated homing gene drives is a promising route for malaria vector control. Integral gene drives (IGDs) are designed to utilize the regulatory sequences of endogenous genes to express only the minimal set of components required for gene drive. In this study, we describe the creation and characterization of the nanosd IGD targeting and inserted into the nanos gene of the malaria vector Anopheles gambiae and show that it achieves high rates of gene drive (97.7% in females, 99.0% in males). We find that homozygous nanosd females but not males show impaired fecundity, and a variable loss of ovary phenotype. Transcriptomic analysis of ovaries points to decreased transcript levels of the nanos gene when harbouring Cas9. As a minimal genetic modification, nanosd does not induce widespread transcriptomic perturbations, and its susceptibility to Plasmodium spp. and Onyong nyong virus infection remains similar to wild-type mosquitoes. Importantly, we find that nanosd propagates efficiently in caged mosquito populations and is maintained as a source of Cas9 after the emergence of drive resistant alleles whilst also mobilising a non-autonomous antiparasitic effector modification. The nanosd gene drive shows promise as a genetic tool for malaria vector control via population modification, and we outline steps towards its further optimization.

synthetic biology↗

bioRxiv2023

Intracellular Plasmodium aquaporin 2 is required for sporozoite production in the mosquito vector and malaria transmission

Malaria remains a devastating disease and, with current measures failing to control its transmission, there is a need for novel interventions. A family of proteins that have long been pursued as potential intervention targets are aquaporins which are channels facilitating the movement of water and other solutes across membranes. We identify a new aquaporin in malaria parasites and demonstrate that it is essential for disease transmission through mosquitoes. Disruption of AQP2 in the human parasite Plasmodium falciparum and the rodent parasite Plasmodium berghei blocks sporozoite production inside oocysts established on mosquito midguts, preventing parasite infection of salivary glands and transmission to a new host. In vivo epitope tagging of AQP2 in P. berghei, combined with immunofluorescence assays, reveals that the protein is localized in previously uncharacterized organelles found in the cytoplasm of gametocytes, ookinetes and sporozoites. The number of these organelles varies between individual parasites and lifecycle stages suggesting that they are likely part of a dynamic endolysosomal system. Phylogenetic analysis confirms that AQP2 is unique to malaria and closely related parasites and most closely related to other intracellular aquaporins. Structure prediction analyses identify several unusual features, including a large accessory extracellular loop and an arginine-to-phenylalanine substitution in the selectivity filter principally determining pore function, a unique feature not found in any aquaporins studied to date. This in conjunction with the requirement of AQP2 for malaria transmission suggests that AQP2 may be a fruitful new target of novel antimalarial interventions.

microbiology↗

bioRxiv2023

TimeTeller: a tool to probe the circadian clock as a multigene dynamical system

AO_SCPLOWBSTRACTC_SCPLOWRecent studies have established that the circadian clock influences onset, progression and therapeutic outcomes in a number of diseases including cancer and heart diseases. Therefore, there is a need for tools to measure the functional state of the molecular circadian clock and its downstream targets in patients. Moreover, the clock is a multi-dimensional stochastic oscillator and there are few tools for analysing it as a system. In this paper we consider the methodology behind Time-Teller, a machine learning tool that analyses the clock as a system and aims to estimate circadian clock function from a single transcriptome by modelling the multi-dimensional state of the clock. We demonstrate its potential for clock systems assessment by applying it to mouse, baboon and human microarray and RNA-seq data and show how to visualise and quantify the global structure of the clock, quantitatively stratify individual transcriptomic samples by clock dysfunction and globally compare clocks across individuals, conditions and tissues thus highlighting its potential relevance for advancing circadian medicine.

systems biology↗

bioRxiv2023

Reverse genetic screen identifies malaria parasite genes required for gametocyte-to-sporozoite development in its mosquito host

Malaria remains one of the most devastating infectious diseases. Reverse genetic screens offer a powerful approach to identify genes and molecular processes governing malaria parasite biology. However, sexual reproduction and complex regulation of gene expression and genotype-phenotype associations in the mosquito have hampered the development of screens in this key part of the parasite lifecycle. We designed a genetic approach in the rodent parasite Plasmodium berghei, which in conjunction with barcode sequencing allowed us to overcome the fertilization roadblock and screen for gametocyte-expressed genes required for parasite infection of the mosquito Anopheles coluzzii. The results confirmed previous findings, validating our approach for scaling up, and identified new genes required for ookinete motility and mosquito midgut infection and for sporozoite development and oocyst egress and salivary gland infection. Our findings can assist efforts to study malaria transmission biology and develop new interventions to control disease transmission.

microbiology↗

bioRxiv2020

Anopheles coluzzii stearoyl-CoA desaturase is essential for adult female survival and reproduction upon blood feeding

Vitellogenesis and oocyte maturation require anautogenous female Anopheles mosquitoes to obtain a bloodmeal from a vertebrate host. The bloodmeal is rich in proteins that are readily broken down into amino acids in the midgut lumen and absorbed by the midgut epithelial cells where they are converted into lipids and then transported to other tissues including ovaries. The stearoyl-CoA desaturase (SCD) plays a pivotal role in this process by converting saturated (SFAs) to unsaturated (UFAs) fatty acids; the latter being essential for maintaining cell membrane fluidity amongst other housekeeping functions. Here, we report the functional and phenotypic characterization of SCD1 in the malaria vector mosquito Anopheles coluzzii. We show that RNA interference (RNAi) silencing of SCD1 and administration of sterculic acid (SA), a small molecule inhibitor of SCD1, significantly impact on the survival and reproduction of female mosquitoes following blood feeding. Microscopic observations reveal that the mosquito thorax is quickly filled with blood, a phenomenon likely caused by the collapse of midgut epithelial cell membranes, and that epithelial cells are depleted of lipid droplets and oocytes fail to mature. Transcriptional profiling shows that genes involved in protein, lipid and carbohydrate metabolism and immunity-related genes are the most affected by SCD1 knock down (KD) in blood-fed mosquitoes. Metabolic profiling reveals that these mosquitoes exhibit increased amounts of saturated fatty acids and TCA cycle intermediates, highlighting the biochemical framework by which the SCD1 KD phenotype manifests as a result of a detrimental metabolic syndrome. Accumulation of SFAs is also the likely cause of the potent immune response observed in the absence of infection, which resembles an auto-inflammatory condition. These data provide insights into mosquito bloodmeal metabolism and lipid homeostasis and could inform efforts to develop novel interventions against mosquito-borne diseases.

microbiology↗

bioRxiv2019

Plasmodium PIMMS43 is required for ookinete evasion of the mosquito complement-like response and sporogonic development in the oocyst

Malaria transmission requires Plasmodium parasites to successfully infect a female Anopheles mosquito, surviving a series of robust innate immune responses. Understanding how parasites evade these responses can highlight new ways to block malaria transmission. We show that ookinete and sporozoite surface protein PIMMS43 is required for Plasmodium ookinete evasion of the Anopheles coluzzii complement-like system and for sporogonic development in the oocyst. Disruption of P. berghei PIMMS43 triggers robust complement activation and ookinete elimination upon mosquito midgut traversal. Silencing the complement-like system restores ookinete-to-oocyst transition. Antibodies that bind PIMMS43 interfere with parasite immune evasion when ingested with the infectious blood meal and significantly reduce the prevalence and intensity of infection. PIMMS43 genetic structure across African P. falciparum populations indicates allelic adaptation to sympatric vector populations. These data significantly add to our understanding of mosquito-parasite interactions and identify PIMMS43 as a target of interventions aiming at malaria transmission blocking.\n\nAuthor summaryMalaria is a devastating disease transmitted among humans through mosquito bites. Mosquito control has significantly reduced clinical malaria cases and deaths in the last decades. However, as mosquito resistance to insecticides is becoming widespread impacting on current control tools, such as insecticide impregnated bed nets and indoor spraying, new interventions are urgently needed, especially those that target disease transmission. Here, we characterize a protein found on the surface of malaria parasites, which serves to evade the mosquito immune system ensuring disease transmission. Neutralization of PIMMS43, either by eliminating it from the parasite genome or by pre-incubating parasites with antibodies that bind to the protein, is shown to inhibit mosquito infection by malaria parasites. Differences in PIMMS43 detected between malaria parasite populations sampled across Africa suggest that these populations have adapted for transmission by different mosquito vectors that are also differentially distributed across the continent. We conclude that interventions targeting PIMMS43 could block malaria parasites inside mosquitoes before they can infect humans.

microbiology↗

bioRxiv2019

Epigenetic regulation underlying Plasmodium berghei gene expression during its developmental transition from host to vector

Epigenetic regulation of gene expression is an important attribute in the survival and adaptation of the malaria parasite Plasmodium in its human host. Our understanding of epigenetic regulation of gene expression in Plasmodium developmental stages beyond asexual replication in the mammalian host is sparse. We used chromatin immune-precipitation (ChIP) and RNA sequencing to create an epigenetic and transcriptomic map of the murine parasite Plasmodium berghei development from asexual blood stages to male and female gametocytes, and finally, to ookinetes. We show that heterochromatin 1 (HP1) almost exclusively associates with variantly expressed gene families at subtelomeric regions and remains stable across stages and various parasite lines. Variant expression based on heterochromatic silencing is observed only in very few genes. In contrast, the active histone mark histone 3 Lysine 9 acetylation (H3K9ac) is found between heterochromatin boundaries and occurs as a sharp peak around the start codon for ribosomal protein genes. H3K9ac occupancy positively correlates with gene transcripts in asexual blood stages, male gametocytes and ookinetes. Interestingly, H3K9ac occupancy does not correlate with transcript abundance in female gametocytes. Finally, we identify novel DNA motifs upstream of ookinete-specific genes thought to be involved in transcriptional activation upon fertilization.

genomics↗

bioRxiv2019

TimeTeller: a New Tool for Precision Circadian Medicine and Cancer Prognosis

Recent studies have established that the circadian clock influences onset, progression and therapeutic outcomes in a number of diseases including cancer and heart disease. Therefore, there is a need for tools to measure the functional state of the circadian clock and its downstream targets in patients. We provide such a tool and demonstrate its clinical relevance by an application to breast cancer where we find a strong link between survival and our measure of clock dysfunction. We use a machine-learning approach and construct an algorithm called TimeTeller which uses the multi-dimensional state of the genes in a transcriptomics analysis of a single biological sample to assess the level of circadian clock dysfunction. We demonstrate how this can distinguish healthy from malignant tissues and demonstrate that the molecular clock dysfunction metric is a potentially new prognostic and predictive breast cancer biomarker that is independent of the main established prognostic factors.

cancer biology↗