scholarly journals Inhibitor of Cysteine Proteases Is Critical for Motility and Infectivity of Plasmodium Sporozoites

mBio ◽  
2013 ◽  
Vol 4 (6) ◽  
Author(s):  
Katja E. Boysen ◽  
Kai Matuschewski
Keyword(s):  
Life Cycle ◽  
Salivary Glands ◽  
Cysteine Proteases ◽  
Gliding Motility ◽  
Parasitic Infections ◽  
Mammalian Host ◽  
Insect Vector ◽  
Mosquito Vector ◽  
Infected Female ◽  
Wide Range

ABSTRACT Malaria is transmitted when motile sporozoites are injected into the dermis by an infected female Anopheles mosquito. Inside the mosquito vector, sporozoites egress from midgut-associated oocysts and eventually penetrate the acinar cells of salivary glands. Parasite-encoded factors with exclusive vital roles in the insect vector can be studied by classical reverse genetics. Here, we characterized the in vivo roles of Plasmodium berghei falstatin/ICP (inhibitor of cysteine proteases). This protein was previously suggested to act as a protease inhibitor during erythrocyte invasion. We show by targeted gene disruption that loss of ICP function does not affect growth inside the mammalian host but causes a complete defect in sporozoite transmission. Sporogony occurred normally in icp(−) parasites, but hemocoel sporozoites showed a defect in continuous gliding motility and infectivity for salivary glands, which are prerequisites for sporozoite transmission to the mammalian host. Absence of ICP correlates with enhanced cleavage of circumsporozoite protein, in agreement with a role as a protease regulator. We conclude that ICP is essential for only the final stages of sporozoite maturation inside the mosquito vector. This study is the first genetic evidence that an ICP is necessary for the productive motility of a eukaryotic parasitic cell. IMPORTANCE Cysteine proteases and their inhibitors are considered ideal drug targets for the treatment of a wide range of diseases, including cancer and parasitic infections. In protozoan parasites, including Leishmania, Trypanosoma, and Plasmodium, cysteine proteases play important roles in life cycle progression. A mouse malaria model provides an unprecedented opportunity to study the roles of a parasite-encoded inhibitor of cysteine proteases (ICP) over the entire parasite life cycle. By precise gene deletion, we found no evidence that ICP influences disease progression or parasite virulence. Instead, we discovered that this factor is necessary for parasite movement and malaria transmission from mosquitoes to mammals. This finding in a fast-moving unicellular protozoan has important implications for malaria intervention strategies and the roles of ICPs in the regulation of eukaryotic cell migration.

scholarly journals Leishmania Protein Kinases: Important Regulators of the Parasite Life Cycle and Molecular Targets for Treating Leishmaniasis

2021 ◽  
Vol 9 (4) ◽  
pp. 691
Author(s):  
Antonia Efstathiou ◽  
Despina Smirlis
Keyword(s):  
Life Cycle ◽  
Protein Kinases ◽  
Clinical Manifestations ◽  
Molecular Targets ◽  
Leishmania Infection ◽  
Mammalian Host ◽  
Insect Vector ◽  
Eukaryotic Protein ◽  
Wide Range ◽  
Eukaryotic Protein Kinases

Leishmania is a protozoan parasite of the trypanosomatid family, causing a wide range of diseases with different clinical manifestations including cutaneous, mucocutaneous and visceral leishmaniasis. According to WHO, one billion people are at risk of Leishmania infection as they live in endemic areas while there are 12 million infected people worldwide. Annually, 0.9–1.6 million new infections are reported and 20–50 thousand deaths occur due to Leishmania infection. As current chemotherapy for treating leishmaniasis exhibits numerous drawbacks and due to the lack of effective human vaccine, there is an urgent need to develop new antileishmanial therapy treatment. To this end, eukaryotic protein kinases can be ideal target candidates for rational drug design against leishmaniasis. Eukaryotic protein kinases mediate signal transduction through protein phosphorylation and their inhibition is anticipated to be disease modifying as they regulate all essential processes for Leishmania viability and completion of the parasitic life cycle including cell-cycle progression, differentiation and virulence. This review highlights existing knowledge concerning the exploitation of Leishmania protein kinases as molecular targets to treat leishmaniasis and the current knowledge of their role in the biology of Leishmania spp. and in the regulation of signalling events that promote parasite survival in the insect vector or the mammalian host.

scholarly journals Metabolic reprogramming during the Trypanosoma brucei life cycle

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 683 ◽  
Author(s):  
Terry K. Smith ◽  
Frédéric Bringaud ◽  
Derek P. Nolan ◽  
Luisa M. Figueiredo
Keyword(s):  
Life Cycle ◽  
Trypanosoma Brucei ◽  
Model Organism ◽  
Protozoan Parasite ◽  
Tsetse Fly ◽  
Metabolic Reprogramming ◽  
Mammalian Host ◽  
Insect Vector ◽  
Environmental Signals ◽  
Cellular Metabolic Activity

Cellular metabolic activity is a highly complex, dynamic, regulated process that is influenced by numerous factors, including extracellular environmental signals, nutrient availability and the physiological and developmental status of the cell. The causative agent of sleeping sickness, Trypanosoma brucei, is an exclusively extracellular protozoan parasite that encounters very different extracellular environments during its life cycle within the mammalian host and tsetse fly insect vector. In order to meet these challenges, there are significant alterations in the major energetic and metabolic pathways of these highly adaptable parasites. This review highlights some of these metabolic changes in this early divergent eukaryotic model organism.

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 Investigating the Chaperone Properties of a Novel Heat Shock Protein, Hsp70.c, fromTrypanosoma brucei

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Adélle Burger ◽  
Michael H. Ludewig ◽  
Aileen Boshoff
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Trypanosoma Brucei ◽  
Mammalian Host ◽  
Insect Vector ◽  
Wide Range ◽  
Response To Stress ◽  
Parasite Biology ◽  
Substrate Binding Domain

The neglected tropical disease, African Trypanosomiasis, is fatal and has a crippling impact on economic development. Heat shock protein 70 (Hsp70) is an important molecular chaperone that is expressed in response to stress and Hsp40 acts as its co-chaperone. These proteins play a wide range of roles in the cell and they are required to assist the parasite as it moves from a cold blooded insect vector to a warm blooded mammalian host. A novel cytosolic Hsp70, fromTrypanosoma brucei, TbHsp70.c, contains an acidic substrate binding domain and lacks the C-terminal EEVD motif. The ability of a cytosolic Hsp40 fromTrypanosoma bruceiJ protein 2, Tbj2, to function as a co-chaperone of TbHsp70.c was investigated. The main objective was to functionally characterize TbHsp70.c to further expand our knowledge of parasite biology. TbHsp70.c and Tbj2 were heterologously expressed and purified and both proteins displayed the ability to suppress aggregation of thermolabile MDH and chemically denatured rhodanese. ATPase assays revealed a 2.8-fold stimulation of the ATPase activity of TbHsp70.c by Tbj2. TbHsp70.c and Tbj2 both demonstrated chaperone activity and Tbj2 functions as a co-chaperone of TbHsp70.c.In vivoheat stress experiments indicated upregulation of the expression levels of TbHsp70.c.

scholarly journals Plasmodium berghei Sporozoites Acquire Virulence and Immunogenicity during Mosquito Hemocoel Transit

2013 ◽  
Vol 82 (3) ◽  
pp. 1164-1172 ◽  
Author(s):  
Yuko Sato ◽  
Georgina N. Montagna ◽  
Kai Matuschewski
Keyword(s):  
Salivary Glands ◽  
Plasmodium Berghei ◽  
Lower Proportion ◽  
Gliding Motility ◽  
Mammalian Host ◽  
Live Attenuated Vaccine ◽  
Experimental Cerebral Malaria ◽  
Content Type ◽  
Vector Borne

ABSTRACTMalaria is a vector-borne disease caused by the single-cell eukaryotePlasmodium. The infectious parasite forms are sporozoites, which originate from midgut-associated oocysts, where they eventually egress and reach the mosquito hemocoel. Sporozoites actively colonize the salivary glands in order to be transmitted to the mammalian host. Whether residence in the salivary glands provides distinct and vital cues for the development of infectivity remains unsolved. In this study, we systematically compared the infectivity ofPlasmodium bergheisporozoites isolated from the mosquito hemocoel and salivary glands. Hemocoel sporozoites display a lower proportion of gliding motility but develop into liver stages when added to cultured hepatoma cells or after intravenous injection into mice. Mice infected by hemocoel sporozoites had blood infections similar to those induced by sporozoites liberated from salivary glands. These infected mice display indistinguishable systemic inflammatory cytokine responses and develop experimental cerebral malaria. When used as metabolically active, live attenuated vaccine, hemocoel sporozoites elicit substantial protection against sporozoite challenge infections. Collectively, these findings show that salivary gland colonization does not influence parasite virulence in the mammalian host when sporozoites are administered intravenously. This conclusion has important implications forin vitrosporozoite production and manufacturing of whole-sporozoite vaccines.

scholarly journals The Plasmodium eukaryotic initiation factor-2α kinase IK2 controls the latency of sporozoites in the mosquito salivary glands

2010 ◽  
Vol 207 (7) ◽  
pp. 1465-1474 ◽  
Author(s):  
Min Zhang ◽  
Clare Fennell ◽  
Lisa Ranford-Cartwright ◽  
Ramanavelan Sakthivel ◽  
Pascale Gueirard ◽  
...  
Keyword(s):  
Salivary Gland ◽  
Life Cycle ◽  
Salivary Glands ◽  
Stress Responses ◽  
Initiation Factor ◽  
Eukaryotic Cells ◽  
Mammalian Host ◽  
Eukaryotic Initiation Factor ◽  
Active Process ◽  
Eif2α Kinase

Sporozoites, the invasive form of malaria parasites transmitted by mosquitoes, are quiescent while in the insect salivary glands. Sporozoites only differentiate inside of the hepatocytes of the mammalian host. We show that sporozoite latency is an active process controlled by a eukaryotic initiation factor-2α (eIF2α) kinase (IK2) and a phosphatase. IK2 activity is dominant in salivary gland sporozoites, leading to an inhibition of translation and accumulation of stalled mRNAs into granules. When sporozoites are injected into the mammalian host, an eIF2α phosphatase removes the PO4 from eIF2α-P, and the repression of translation is alleviated to permit their transformation into liver stages. In IK2 knockout sporozoites, eIF2α is not phosphorylated and the parasites transform prematurely into liver stages and lose their infectivity. Thus, to complete their life cycle, Plasmodium sporozoites exploit the mechanism that regulates stress responses in eukaryotic cells.

The role of membrane transporters in Leishmania virulence

2017 ◽  
Vol 1 (6) ◽  
pp. 601-611 ◽  
Author(s):  
Snezhana Akpunarlieva ◽  
Richard Burchmore
Keyword(s):  
Life Cycle ◽  
Amino Acid ◽  
Membrane Transporters ◽  
Mammalian Host ◽  
Insect Vector ◽  
Parasite Life Cycle ◽  
Severe Morbidity ◽  
Intracellular Amastigotes ◽  
Genomic Analyses

Leishmania are parasitic protozoa which infect humans and cause severe morbidity and mortality. Leishmania parasitise as extracellular promastigotes in the insect vector and as intracellular amastigotes in the mammalian host. Cycling between hosts involves implementation of stringent and co-ordinated responses to shifting environmental conditions. One of the key dynamic aspects of Leishmania biology is substrate acquisition and metabolism. Genomic analyses have revealed that Leishmania encode many putative membrane transporters, many of which are differentially expressed during the parasite life cycle. Only a small fraction of these transporters, however, have been functionally characterised. Currently, most information is available about nutrient transporters, mainly involved in carbohydrate, amino acid, nucleobase and nucleoside, cofactor, and ion acquisition. Several have apparent roles in Leishmania virulence and will be discussed in this perspective.

scholarly journals Disruption of Plasmodium Sporozoite Transmission by Depletion of Sporozoite Invasion-Associated Protein 1

2009 ◽  
Vol 8 (4) ◽  
pp. 640-648 ◽  
Author(s):  
Sabine Engelmann ◽  
Olivier Silvie ◽  
Kai Matuschewski
Keyword(s):  
Salivary Gland ◽  
Salivary Glands ◽  
Gliding Motility ◽  
Insect Vector ◽  
Targeted Disruption ◽  
Apicomplexan Parasites ◽  
Complex Development ◽  
Fluorescent Tagging ◽  
And Migration

ABSTRACT Accumulation of infectious Plasmodium sporozoites in Anopheles spp. salivary glands marks the final step of the complex development of the malaria parasite in the insect vector. Sporozoites are formed inside midgut-associated oocysts and actively egress into the mosquito hemocoel. Traversal of the salivary gland acinar cells correlates with the sporozoite's capacity to perform continuous gliding motility. Here, we characterized the cellular role of the Plasmodium berghei sporozoite invasion-associated protein 1 (SIAP-1). Intriguingly, SIAP-1 orthologs are found exclusively in apicomplexan hemoprotozoa, parasites that are transmitted by arthropod vectors, e.g., Plasmodium, Babesia, and Theileria species. By fluorescent tagging with mCherry, we show that SIAP-1 is expressed in oocyst-derived and salivary gland-associated sporozoites, where it accumulates at the apical tip. Targeted disruption of SIAP-1 does not affect sporozoite formation but causes a partial defect in sporozoite egress from oocysts and abolishes sporozoite colonization of mosquito salivary glands. Parasites with the siap-1(−) mutation are blocked in their capacity to perform continuous gliding motility. We propose that arthropod-transmitted apicomplexan parasites specifically express secretory factors, such as SIAP-1, that mediate efficient oocyst exit and migration to the salivary glands.

scholarly journals Metabolic reprogramming during the Trypanosoma brucei life cycle

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 683 ◽  
Author(s):  
Terry K. Smith ◽  
Frédéric Bringaud ◽  
Derek P. Nolan ◽  
Luisa M. Figueiredo
Keyword(s):  
Life Cycle ◽  
Trypanosoma Brucei ◽  
Model Organism ◽  
Protozoan Parasite ◽  
Tsetse Fly ◽  
Metabolic Reprogramming ◽  
Mammalian Host ◽  
Insect Vector ◽  
Environmental Signals ◽  
Cellular Metabolic Activity

Cellular metabolic activity is a highly complex, dynamic, regulated process that is influenced by numerous factors, including extracellular environmental signals, nutrient availability and the physiological and developmental status of the cell. The causative agent of sleeping sickness, Trypanosoma brucei, is an exclusively extracellular protozoan parasite that encounters very different extracellular environments during its life cycle within the mammalian host and tsetse fly insect vector. In order to meet these challenges, there are significant alterations in the major energetic and metabolic pathways of these highly adaptable parasites. This review highlights some of these metabolic changes in this early divergent eukaryotic model organism.

scholarly journals The Malaria Cell Atlas: a comprehensive reference of single parasite transcriptomes across the complete Plasmodium life cycle

2019 ◽  
Author(s):  
Virginia M. Howick ◽  
Andrew Russell ◽  
Tallulah Andrews ◽  
Haynes Heaton ◽  
Adam J. Reid ◽  
...  
Keyword(s):  
Life Cycle ◽  
Developmental Stages ◽  
Single Cells ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Malaria Parasites ◽  
Data Set ◽  
Human Malaria Parasite ◽  
Gene Usage ◽  
Comprehensive Reference

Malaria parasites adopt a remarkable variety of morphological life stages as they transition through multiple mammalian host and mosquito vector environments. Here we profile the single-cell transcriptomes of thousands of individual parasites, deriving the first high-resolution transcriptional atlas of the entire Plasmodium berghei life cycle. We then use our atlas to precisely define developmental stages of single cells from three different human malaria parasite species, including parasites isolated directly from infected individuals. The Malaria Cell Atlas provides both a comprehensive view of gene usage in a complex eukaryotic parasite and an open access reference data set for the study of malaria parasites.

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