scholarly journals Extensive Transcriptional and Translational Regulation Occur During the Maturation of Malaria Parasite Sporozoites

2019 ◽  
Author(s):  
Scott E. Lindner ◽  
Kristian E. Swearingen ◽  
Melanie J. Shears ◽  
Michael P. Walker ◽  
Erin N. Vrana ◽  
...  
Keyword(s):  
Translational Regulation ◽  
Plasmodium Yoelii ◽  
Translational Repression ◽  
Infected Mosquito ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Gene Products ◽  
Cycle Progression ◽  
Infectious State ◽  
Validation Experiments

AbstractPlasmodium sporozoites are transmitted from an infected mosquito to mammals in which they infect the liver. The infectivity profile of sporozoites changes as they egress from oocysts on the mosquito midgut into the hemocoel, and then invade the salivary glands, where they maintain a poised and infectious state until transmission occurs. Upon transmission, the sporozoite must then navigate the host skin, vasculature, and liver. All of these feats require distinct repertoires of proteins and capabilities that are coordinated in an appropriate temporal manner. Here, we report the comprehensive and dynamic transcriptomes and proteomes of both oocyst sporozoite and salivary gland sporozoite stages in both rodent-infectious Plasmodium yoelii parasites and human-infectious Plasmodium falciparum parasites. These data robustly define mRNAs and proteins that are Upregulated in Oocyst Sporozoites (UOS) or Upregulated in Infectious Sporozoites (UIS), which include critical gene products for sporozoite functions, as well as many of unknown importance that are similarly regulated. Moreover, we found that Plasmodium uses two overlapping, extensive, and independent programs of translational repression across sporozoite maturation to temporally regulate specific genes necessary to successfully navigate the mosquito vector and mammalian host environments. Finally, gene-specific validation experiments of selected, translationally repressed transcripts in P. yoelii confirmed the interpretations of the global transcriptomic and proteomic datasets. Together, these data indicate that two waves of translational repression are implemented and relieved at different times in sporozoite maturation to promote its successful life cycle progression.

scholarly journals Cyclic GMP Balance Is Critical for Malaria Parasite Transmission from the Mosquito to the Mammalian Host

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Viswanathan Lakshmanan ◽  
Matthew E. Fishbaugher ◽  
Bob Morrison ◽  
Michael Baldwin ◽  
Michael Macarulay ◽  
...  
Keyword(s):  
Salivary Glands ◽  
Cyclic Gmp ◽  
Cyclic Nucleotide ◽  
Malaria Parasite ◽  
Plasmodium Yoelii ◽  
Pcr Analysis ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Parasite Transmission ◽  
Mosquito Bite

ABSTRACT Transmission of malaria occurs during Anopheles mosquito vector blood meals, when Plasmodium sporozoites that have invaded the mosquito salivary glands are delivered to the mammalian host. Sporozoites display a unique form of motility that is essential for their movement across cellular host barriers and invasion of hepatocytes. While the molecular machinery powering motility and invasion is increasingly well defined, the signaling events that control these essential parasite activities have not been clearly delineated. Here, we identify a phosphodiesterase (PDEγ) in Plasmodium, a regulator of signaling through cyclic nucleotide second messengers. Reverse transcriptase PCR (RT-PCR) analysis and epitope tagging of endogenous PDEγ detected its expression in blood stages and sporozoites of Plasmodium yoelii. Deletion of PDEγ (pdeγ−) rendered sporozoites nonmotile, and they failed to invade the mosquito salivary glands. Consequently, PDEγ deletion completely blocked parasite transmission by mosquito bite. Strikingly, pdeγ− sporozoites showed dramatically elevated levels of cyclic GMP (cGMP), indicating that a perturbation in cyclic nucleotide balance is involved in the observed phenotypic defects. Transcriptome sequencing (RNA-Seq) analysis of pdeγ− sporozoites revealed reduced transcript abundance of genes that encode key components of the motility and invasion apparatus. Our data reveal a crucial role for PDEγ in maintaining the cyclic nucleotide balance in the malaria parasite sporozoite stage, which in turn is essential for parasite transmission from mosquito to mammal. IMPORTANCE Malaria is a formidable threat to human health worldwide, and there is an urgent need to identify novel drug targets for this parasitic disease. The parasite is transmitted by mosquito bite, inoculating the host with infectious sporozoite stages. We show that cellular signaling by cyclic nucleotides is critical for transmission of the parasite from the mosquito vector to the mammalian host. Parasite phosphodiesterase γ is essential for maintaining cyclic nucleotide balance, and its deletion blocks transmission of sporozoites. A deeper understanding of the signaling mechanisms involved in transmission might inform the discovery of novel drugs that interrupt this essential step in the parasite life cycle.

scholarly journals A Plasmodium yoelii Mei2-Like RNA Binding Protein Is Essential for Completion of Liver Stage Schizogony

2016 ◽  
Vol 84 (5) ◽  
pp. 1336-1345 ◽  
Author(s):  
Dorender A. Dankwa ◽  
Marshall J. Davis ◽  
Stefan H. I. Kappe ◽  
Ashley M. Vaughan
Keyword(s):  
Rna Binding ◽  
Rna Binding Proteins ◽  
Plasmodium Yoelii ◽  
Parasite Development ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Wild Type ◽  
Liver Stage ◽  
Content Type ◽  
Stage Development

Plasmodiumparasites employ posttranscriptional regulatory mechanisms as their life cycle transitions between host cell invasion and replication within both the mosquito vector and mammalian host. RNA binding proteins (RBPs) provide one mechanism for modulation of RNA function. To explore the role ofPlasmodiumRBPs during parasite replication, we searched for RBPs that might play a role during liver stage development, the parasite stage that exhibits the most extensive growth and replication. We identified a parasite ortholog of theMei2(Meiosisinhibited 2) RBP that is conserved amongPlasmodiumspecies (PlasMei2) and exclusively transcribed in liver stage parasites. Epitope-taggedPlasmodium yoeliiPlasMei2 was expressed only during liver stage schizogony and showed an apparent granular cytoplasmic location. Knockout ofPlasMei2(plasmei2−) inP. yoeliionly affected late liver stage development. TheP. yoeliiplasmei2−liver stage size increased progressively until late in development, similar to wild-type parasite development. However,P. yoeliiplasmei2−liver stage schizonts exhibited an abnormal DNA segregation phenotype and failed to form exoerythrocytic merozoites. Consequently the cellular integrity ofP. yoeliiplasmei2−liver stages became increasingly compromised late in development and the majority ofP. yoeliiplasmei2−underwent cell death by the time wild-type liver stages mature and release merozoites. This resulted in a complete block ofP. yoeliiplasmei2−transition from liver stage to blood stage infection in mice. Our results show for the first time the importance of aPlasmodiumRBP in the coordinated progression of late liver stage schizogony and maturation of new invasive forms.

scholarly journals Standard selection treatments with sulfadiazine limit Plasmodium yoelii host-to-vector transmission

2022 ◽  
Author(s):  
Kelly T. Rios ◽  
Taylor M. Dickson ◽  
Scott E Lindner
Keyword(s):  
Culture Media ◽  
Competitive Inhibitor ◽  
Plasmodium Yoelii ◽  
Infected Mosquito ◽  
Mosquito Vector ◽  
Intensity Of Infection ◽  
Asexual Blood Stage ◽  
Vector Transmission

Some early antimalarial drugs have been repurposed for experimental applications, thus extending their utility well beyond the point when resistance becomes prevalent in circulating parasite populations. One such drug is sulfadiazine, which is an analog of p-aminobenzoic acid (pABA), and acts as a competitive inhibitor of dihydropteroate synthase, which is an essential enzyme in the parasite's folate synthesis pathway that is required for DNA synthesis. Sulfadiazine treatment of mice infected with P. yoelii and P. berghei is routinely used to enrich for gametocytes by killing asexual blood stage parasites, but it is not well known if the exposed gametocytes are perturbed or if there is a detrimental effect on transmission. To determine if there was a significant effect of sulfadiazine exposure upon host-to-vector transmission, we transmitted Plasmodium yoelii (17XNL strain) parasites to Anopheles stephensi mosquitoes and evaluated the prevalence of infection (percent of mosquitoes infected) and intensity of infection (number of oocysts per infected mosquito) under different sulfadiazine treatment conditions of the mouse or of the mosquitoes. We observed that parasites exposed to sulfadiazine either in the mouse host or in the mosquito vector had a reduction in both the number of mosquitoes that became infected and in the intensity of infection compared to untreated controls. We also observed that provision of freshly prepared pABA in the mosquito sugar water could only marginally overcome the defects caused by sulfadiazine treatment. In contrast, we determined that gametocytes exposed to sulfadiazine were able to be fertilized and develop into morphologically mature ookinetes in vitro, and thus that sulfadiazine exposure in the host may be reversible if the drug is washed out and the parasites are supplemented with pABA in the culture media. Overall, this indicates that sulfadiazine dampens host-to-vector transmission, and that this inhibition can only be partially overcome by exposure to fresh pABA in vivo and in vitro. Because gametocytes are of great interest for developing transmission blocking interventions, we recommend that less disruptive approaches for gametocyte enrichment be used in order to study minimally perturbed parasites.

scholarly journals Infecting mosquitoes alters DENV-2 characteristics and enhances hemorrhage-induction potential in Stat1-/- mice

2021 ◽  
Vol 15 (8) ◽  
pp. e0009728
Author(s):  
Ka Wan Cheang ◽  
Wen-Yu Chen ◽  
Betty A. Wu-Hsieh ◽  
Shin-Hong Shiao
Keyword(s):  
Low Dose ◽  
Infected Mosquito ◽  
Effective Vaccine ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Salivary Gland Extract ◽  
Mammalian Cell Lines ◽  
Gland Extract ◽  
Mosquito Saliva ◽  
Severe Hemorrhage

Dengue is one of the most prevalent arthropod-borne viral diseases in humans. There is still no effective vaccine or treatment to date. Previous studies showed that mosquito-derived factors present in saliva or salivary gland extract (SGE) contribute to the pathogenesis of dengue. In this study, we aimed to investigate the interplay between mosquito vector and DENV and to address the question of whether the mosquito vector alters the virus that leads to consequential disease manifestations in the mammalian host. DENV2 cultured in C6/36 cell line (culture-DENV2) was injected to Aedes aegypti intrathoracically. Saliva was collected from infected mosquitoes 7 days later. Exploiting the sensitivity of Stat1-/- mice to low dose of DENV2 delivered intradermally, we showed that DENV2 collected in infected mosquito saliva (msq-DENV2) induced more severe hemorrhage in mice than their culture counterpart. Msq-DENV2 was characterized by smaller particle size, larger plaque size and more rapid growth in mosquito as well as mammalian cell lines compared to culture-DENV2. In addition, msq-DENV2 was more efficient than culture-DENV2 in inducing Tnf mRNA production by mouse macrophage. Together, our results point to the possibility that the mosquito vector provides an environment that alters DENV2 by changing its growth characteristics as well as its potential to cause disease.

scholarly journals Transcriptomics and proteomics reveal two waves of translational repression during the maturation of malaria parasite sporozoites

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Scott E. Lindner ◽  
Kristian E. Swearingen ◽  
Melanie J. Shears ◽  
Michael P. Walker ◽  
Erin N. Vrana ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Salivary Gland ◽  
Protein Expression ◽  
Salivary Glands ◽  
Malaria Parasite ◽  
Plasmodium Yoelii ◽  
Translational Repression ◽  
Successful Development ◽  
Regulate Protein ◽  
Validation Experiments

Abstract Plasmodium sporozoites are transmitted from infected mosquitoes to mammals, and must navigate the host skin and vasculature to infect the liver. This journey requires distinct proteomes. Here, we report the dynamic transcriptomes and proteomes of both oocyst sporozoites and salivary gland sporozoites in both rodent-infectious Plasmodium yoelii parasites and human-infectious Plasmodium falciparum parasites. The data robustly define mRNAs and proteins that are upregulated in oocyst sporozoites (UOS) or upregulated in infectious sporozoites (UIS) within the salivary glands, including many that are essential for sporozoite functions in the vector and host. Moreover, we find that malaria parasites use two overlapping, extensive, and independent programs of translational repression across sporozoite maturation to temporally regulate protein expression. Together with gene-specific validation experiments, these data indicate that two waves of translational repression are implemented and relieved at different times during sporozoite maturation, migration and infection, thus promoting their successful development and vector-to-host transition.

scholarly journals Preparing for Transmission: Gene Regulation in Plasmodium Sporozoites

2021 ◽  
Vol 10 ◽  
Author(s):  
Sylvie Briquet ◽  
Carine Marinach ◽  
Olivier Silvie ◽  
Catherine Vaquero
Keyword(s):  
Gene Expression ◽  
Translational Repression ◽  
Mammalian Host ◽  
Insect Vector ◽  
Mosquito Vector ◽  
Parasite Life Cycle ◽  
Transcriptional Regulatory ◽  
Transcriptional Regulatory Mechanisms ◽  
Regulated Gene Expression ◽  
Anopheline Mosquitoes

Plasmodium sporozoites are transmitted to mammals by anopheline mosquitoes and first infect the liver, where they transform into replicative exoerythrocytic forms, which subsequently release thousands of merozoites that invade erythrocytes and initiate the malaria disease. In some species, sporozoites can transform into dormant hypnozoites in the liver, which cause malaria relapses upon reactivation. Transmission from the insect vector to a mammalian host is a critical step of the parasite life cycle, and requires tightly regulated gene expression. Sporozoites are formed inside oocysts in the mosquito midgut and become fully infectious after colonization of the insect salivary glands, where they remain quiescent until transmission. Parasite maturation into infectious sporozoites is associated with reprogramming of the sporozoite transcriptome and proteome, which depends on multiple layers of transcriptional and post-transcriptional regulatory mechanisms. An emerging scheme is that gene expression in Plasmodium sporozoites is controlled by alternating waves of transcription activity and translational repression, which shape the parasite RNA and protein repertoires for successful transition from the mosquito vector to the mammalian host.

scholarly journals The fibrinolytic system enables the onset of Plasmodium infection in the mosquito vector and the mammalian host

2021 ◽  
Vol 7 (6) ◽  
pp. eabe3362 ◽  
Author(s):  
Thiago Luiz Alves e Silva ◽  
Andrea Radtke ◽  
Amanda Balaban ◽  
Tales Vicari Pascini ◽  
Zarna Rajeshkumar Pala ◽  
...  
Keyword(s):  
Plasminogen Activators ◽  
Fibrinolytic System ◽  
Matrix Proteins ◽  
Parasite Development ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Plasminogen Activation ◽  
Plasmodium Infection ◽  
Human Plasminogen ◽  
Vertebrate Hosts

Plasmodium parasites must migrate across proteinaceous matrices to infect the mosquito and vertebrate hosts. Plasmin, a mammalian serine protease, degrades extracellular matrix proteins allowing cell migration through tissues. We report that Plasmodium gametes recruit human plasminogen to their surface where it is processed into plasmin by corecruited plasminogen activators. Inhibition of plasminogen activation arrests parasite development early during sexual reproduction, before ookinete formation. We show that increased fibrinogen and fibrin in the blood bolus, which are natural substrates of plasmin, inversely correlate with parasite infectivity of the mosquito. Furthermore, we show that sporozoites, the parasite form transmitted by the mosquito to humans, also bind plasminogen and plasminogen activators on their surface, where plasminogen is activated into plasmin. Surface-bound plasmin promotes sporozoite transmission by facilitating parasite migration across the extracellular matrices of the dermis and of the liver. The fibrinolytic system is a potential target to hamper Plasmodium transmission.

scholarly journals Plasmodium yoelii Sporozoites with Simultaneous Deletion of P52 and P36 Are Completely Attenuated and Confer Sterile Immunity against Infection

2007 ◽  
Vol 75 (8) ◽  
pp. 3758-3768 ◽  
Author(s):  
Mehdi Labaied ◽  
Anke Harupa ◽  
Ronald F. Dumpit ◽  
Isabelle Coppens ◽  
Sebastian A. Mikolajczak ◽  
...  
Keyword(s):  
Host Cell ◽  
Genetic Manipulation ◽  
Parasitophorous Vacuole ◽  
Plasmodium Yoelii ◽  
Blood Stage ◽  
Mammalian Host ◽  
Electron Microscopic ◽  
Rodent Host ◽  
Blood Stage Infection ◽  
Stage Infection

ABSTRACT Malaria infection starts when sporozoites are transmitted to the mammalian host during a mosquito bite. Sporozoites enter the blood circulation, reach the liver, and infect hepatocytes. The formation of a parasitophorous vacuole (PV) establishes their intracellular niche. Recently, two members of the 6-Cys domain protein family, P52 and P36, were each shown to play an important albeit nonessential role in Plasmodium berghei sporozoite infectivity for the rodent host. Here, we generated p52/p36-deficient Plasmodium yoelii parasites by the simultaneous deletion of both genes using a single genetic manipulation. p52/p36-deficient parasites exhibited normal progression through the life cycle during blood-stage infection, transmission to mosquitoes, mosquito-stage development, and sporozoite infection of the salivary glands. p52/p36-deficient sporozoites also showed normal motility and cell traversal activity. However, immunofluorescence analysis and electron microscopic observations revealed that p52/p36-deficient parasites did not form a PV within hepatocytes in vitro and in vivo. The p52/p36-deficient parasites localized as free entities in the host cell cytoplasm or the host cell nucleoplasm and did not develop as liver stages. Consequently, they did not cause blood-stage infections even at high sporozoite inoculation doses. Mice immunized with p52/p36-deficient sporozoites were completely protected against infectious sporozoite challenge. Our results demonstrate for the first time the generation of two-locus gene deletion-attenuated parasites that infect the liver but do not progress to blood-stage infection. The study will critically guide the design of Plasmodium falciparum live attenuated malaria vaccines.

scholarly journals P-bodies and the miRNA pathway regulate translational repression of bicoid mRNA during Drosophila melanogaster oogenesis

2018 ◽  
Author(s):  
John M. McLaughlin ◽  
Daniel F.Q. Smith ◽  
Irina E. Catrina ◽  
Diana P. Bratu
Keyword(s):  
Drosophila Melanogaster ◽  
Small Rna ◽  
Translational Regulation ◽  
Translational Repression ◽  
Temporal Regulation ◽  
P Bodies ◽  
Maternal Transcripts ◽  
Spatio Temporal ◽  
Mirna Pathway ◽  
Rna Pathways

ABSTRACTEmbryonic axis patterning in Drosophila melanogaster is partly achieved by mRNAs that are maternally localized to the oocyte; the spatio-temporal regulation of these transcripts’ stability and translation is a characteristic feature of oogenesis. While protein regulatory factors are necessary for the translational regulation of some maternal transcripts (e.g. oskar and gurken), small RNA pathways are also known to regulate mRNA stability and translation in eukaryotes. MicroRNAs (miRNAs) are small RNA regulators of gene expression, widely conserved throughout eukaryotic genomes and essential for animal development. The main D. melanogaster anterior determinant, bicoid, is maternally transcribed, but it is not translated until early embryogenesis. We investigated the possibility that its translational repression during oogenesis is mediated by miRNA activity. We found that the bicoid 3’UTR contains a highly conserved, predicted binding site for miR-305. Our studies reveal that miR-305 regulates the translation of a reporter gene containing the bicoid 3’UTR in cell culture, and that miR-305 only partially contributes to bicoid mRNA translational repression during oogenesis. We also found that Processing bodies (P-bodies) in the egg chamber may play a role in stabilizing bicoid and other maternal transcripts. Here, we offer insights into the possible role of P-bodies and the miRNA pathway in the translational repression of bicoid mRNA during oogenesis.

Vector survival and parasite infection: the effect of Wuchereria bancrofti on its vector Culex quinquefasciatus

Parasitology ◽  
2004 ◽  
Vol 129 (1) ◽  
pp. 43-50 ◽  
Author(s):  
K. KRISHNAMOORTHY ◽  
S. SUBRAMANIAN ◽  
G. J. VAN OORTMARSSEN ◽  
J. D. F. HABBEMA ◽  
P. K. DAS
Keyword(s):  
Incubation Period ◽  
Culex Quinquefasciatus ◽  
Geometric Mean ◽  
Wuchereria Bancrofti ◽  
Parasite Load ◽  
Infected Mosquito ◽  
Parasite Development ◽  
Mosquito Vector ◽  
Extrinsic Incubation Period ◽  
Parasite Loss

This paper investigates a cohort of 2187 laboratory reared Culex quinquefasciatus fed on 69 human volunteers, including 59 persons with different levels of Wuchereria bancrofti microfilariae and 10 without microfilaria. Mosquitoes were followed until death. Mosquito survival was analysed in relation to the level of microfilaria in the human and larval count in the dead mosquito. Vector mortality during the extrinsic incubation period (12 days post-engorgement) was significantly higher in mosquitoes fed on microfilaraemic volunteers (50%) than in those fed on amicrofilaraemics (29%). Both the percentage infected and the geometric mean parasite density was significantly higher among mosquitoes which died before 13 days (45% infected and 10 larvae per infected mosquito) than those surviving beyond 13 days (39% and 2·2), suggesting a parasite loss of more than 80% during the extrinsic incubation period. A large proportion (62%) of the mosquitoes that died during the early of phase of parasite development were infected (36% in low, 26% in medium and 90% in high human Mf-density). Survival analysis showed that the parasite load in mosquitoes and the human Mf-density for a given parasite load are independent risk factors of vector survival. Overall, the hazard of dying was found to be 11–15 times higher among mosquitoes fed on microfilaraemic volunteers than those fed on amicrofilaraemics. The hazard doubles for every increase of about 60–70 parasites in the vector. As a consequence of the parasite-induced reduction in vector survival, the transmission success of the parasite is reduced. The implication of the results on control/elimination of lymphatic filariasis using mass-drug administration is discussed.

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