scholarly journals Supression of Perforin-like Protein pores inhibitPlasmodiummultistage-growth, transmission and erythrocyte senescence

2019 ◽  
Author(s):  
Swati Garg ◽  
Abhishek Shivappagowdar ◽  
Rahul S. Hada ◽  
Rajagopal Ayana ◽  
Chandramohan Bathula ◽  
...  
Keyword(s):  
Life Cycle ◽  
Pore Formation ◽  
Host Cells ◽  
Parasite Development ◽  
Parasite Life Cycle ◽  
Efficient Treatment ◽  
Transmission Blocking ◽  
Multi Stage ◽  
Macpf Domain ◽  
Multiple Stages

AbstractThe pore formingPlasmodiumperforin like proteins (PPLP), expressed in all stages of the parasite life cycle are central drivers for host interactions critical for completion of parasite life cycle and high transmission rates. The high sequence similarity in the central membrane attack complex/ perforin (MACPF) domain and consequent functional overlaps defines them as an attractive target for the development of multi-stage antimalarials. Herein we evaluated the mechanism of pan active function of central, highly conserved region of PPLPs, MACPF domain (PMD) and inhibitory potential of specifically designed anti-PMD chemo. TheE. coliexpressed rPMD interacts with erythrocyte membrane and form pores of ~10.5 nm height and ~24.3 nm diameter leading to haemoglobin release and dextran uptake. The treatment with PMD induced erythrocytes senescence at 48 hours which can account for the physiological effect of disseminated PLPs in loss of circulating erythrocytes inducing anemia during malaria infection. The anti-PMD inhibitors effectively blocked intraerythrocytic growth by suppressing invasion and egress of merozoites and protecting against erythrocyte senescence. Moreover, these inhibitors also blocked the hepatic stage and transmission stage parasite development suggesting multi-stage and transmission-blocking potential of these inhibitors. Additionally, the erythrocyte senescence protective potential of PMD inhibitors can be used to occlude PPLPs mediated severe malarial anemia. Further these inhibitors can be developed with a potential to protect against severity of the disease.Author SummaryMalaria continues to be a major global health threat despite of several exciting improvements in the treatment and prevention of the disease. One of the major concerns in the development of therapy is the emergence of the drug resistance. But for the efficient treatment regime, targeting multiple stages including host and vector would serve as an ideal therapy. Perforin like proteins (PLPs) are eukaryotic pore forming proteins that are highly conserved in the apicomplexan parasites. These play crucial roles in entry and exit of parasites from the host cells and establish infection at multiple stages ofPlasmodium spp.life cycle. Understanding the mechanism of pore formation by smaller, functional, pan-active scaffold of PLPs can serve as a target for development of cross stage protection. Here, using various biochemical, biophysical and pharmacological evidences, we validate the activity and characterize the pore formation of PLPs on erythrocytes. Further, our specifically designed inhibitors could restrict this pore formation and impede the exit/entry of the parasites. Moreover, these inhibitors could also exert multiple stage inhibition and rescue the uninfected erythrocytes from death. Together, this study highlights the mechanism of pore formation by PPLPs and evaluates their potential for the development of pan-active inhibitors to provide both symptomatic and transmission blocking cure for malaria.

scholarly journals Dual Plasmepsin-Targeting Antimalarial Agents Disrupt Multiple Stages of the Malaria Parasite Life Cycle

2020 ◽  
Vol 27 (4) ◽  
pp. 642-658.e12 ◽  
Author(s):  
Paola Favuzza ◽  
Manuel de Lera Ruiz ◽  
Jennifer K. Thompson ◽  
Tony Triglia ◽  
Anna Ngo ◽  
...  
Keyword(s):  
Life Cycle ◽  
Malaria Parasite ◽  
Parasite Life Cycle ◽  
Antimalarial Agents ◽  
Multiple Stages

scholarly journals Enhanced Egress of Intracellular Eimeria tenella Sporozoites by Splenic Lymphocytes from Coccidian-Infected Chickens

2011 ◽  
Vol 79 (8) ◽  
pp. 3465-3470 ◽  
Author(s):  
Xiaojuan Dong ◽  
Ghada H. Abdelnabi ◽  
Sung H. Lee ◽  
Guangxing Li ◽  
Hong Jin ◽  
...  
Keyword(s):  
Life Cycle ◽  
Mononuclear Cells ◽  
Interleukin 2 ◽  
Eimeria Tenella ◽  
Host Cells ◽  
Infected Host ◽  
Splenic Lymphocytes ◽  
Parasite Life Cycle ◽  
Trypan Blue Exclusion ◽  
Content Type

ABSTRACTEgress, which describes the mechanism that some intracellular parasites use to exit from parasitophorous vacuoles and host cells, plays a very important role in the parasite life cycle and is central toEimeriapropagation and pathogenesis. Despite the importance of egress in the intracellular parasite's life cycle, very little information is known on this process compared to other steps, e.g., invasion. The present study was conducted to investigate the interplay between the host adaptive immune system andEimeriaegression. Splenic lymphocytes or soluble immune factors were incubated with parasite-infected host cells for 3 or 5 h, and the percentage of egress was calculated according to an established formula. Viability of egressed parasites and host cells was tested using trypan blue exclusion and annexin V and propidium iodide staining, respectively. We found that premature egression of sporozoites fromEimeria tenella-infected primary chicken kidney cells or from chicken peripheral blood mononuclear cells occurred when the cells were coculturedin vitrowith spleen lymphocytes fromE. tenella-infected chickens but not when they were cocultured with splenocytes from uninfected chickens.Eimeria-specific antibodies and cytokines (gamma interferon [IFN-γ], interleukin-2 [IL-2], and IL-15), derived fromE. tenella-primed B and T lymphocytes, respectively, were capable of promoting premature egress of sporozoites from infected host cells. Both egressed parasites and host cells were viable, although the latter showed reduced reinvasion ability. These results suggest a novel, immune-mediated mechanism that the host exploits to interrupt the normalEimerialife cyclein vivoand thereby block the release of mature parasites into the environment.

scholarly journals Calcium in the Backstage of Malaria Parasite Biology

2021 ◽  
Vol 11 ◽  
Author(s):  
Lucas Silva de Oliveira ◽  
Marcos Rodrigo Alborghetti ◽  
Renata Garcia Carneiro ◽  
Izabela Marques Dourado Bastos ◽  
Rogerio Amino ◽  
...  
Keyword(s):  
Life Cycle ◽  
Protein Kinases ◽  
Malaria Parasite ◽  
Developmental Stages ◽  
Receptor Gene ◽  
Food Vacuole ◽  
Parasite Development ◽  
Cell Infection ◽  
Parasite Life Cycle ◽  
Downstream Signaling

The calcium ion (Ca2+) is a ubiquitous second messenger involved in key biological processes in prokaryotes and eukaryotes. In Plasmodium species, Ca2+ signaling plays a central role in the parasite life cycle. It has been associated with parasite development, fertilization, locomotion, and host cell infection. Despite the lack of a canonical inositol-1,4,5-triphosphate receptor gene in the Plasmodium genome, pharmacological evidence indicates that inositol-1,4,5-triphosphate triggers Ca2+ mobilization from the endoplasmic reticulum. Other structures such as acidocalcisomes, food vacuole and mitochondria are proposed to act as supplementary intracellular Ca2+ reservoirs. Several Ca2+-binding proteins (CaBPs) trigger downstream signaling. Other proteins with no EF-hand motifs, but apparently involved with CaBPs, are depicted as playing an important role in the erythrocyte invasion and egress. It is also proposed that a cross-talk among kinases, which are not members of the family of Ca2+-dependent protein kinases, such as protein kinases G, A and B, play additional roles mediated indirectly by Ca2+ regulation. This statement may be extended for proteins directly related to invasion or egress, such as SUB1, ERC, IMC1I, IMC1g, GAP45 and EBA175. In this review, we update our understanding of aspects of Ca2+-mediated signaling correlated to the developmental stages of the malaria parasite life cycle.

scholarly journals Glutamine Analogues Impair Cell Proliferation, the Intracellular Cycle and Metacyclogenesis in Trypanosoma cruzi

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1628
Author(s):  
Rodolpho Ornitz Oliveira Souza ◽  
Marcell Crispim ◽  
Ariel Mariano Silber ◽  
Flávia Silva Damasceno
Keyword(s):  
Cell Proliferation ◽  
Life Cycle ◽  
Trypanosoma Cruzi ◽  
Host Cells ◽  
Glutamine Metabolism ◽  
Complex Life Cycle ◽  
Mammalian Host ◽  
Developmental Cycle ◽  
Parasite Life Cycle

Trypanosoma cruzi is the aetiologic agent of Chagas disease, which affects people in the Americas and worldwide. The parasite has a complex life cycle that alternates among mammalian hosts and insect vectors. During its life cycle, T. cruzi passes through different environments and faces nutrient shortages. It has been established that amino acids, such as proline, histidine, alanine, and glutamate, are crucial to T. cruzi survival. Recently, we described that T. cruzi can biosynthesize glutamine from glutamate and/or obtain it from the extracellular environment, and the role of glutamine in energetic metabolism and metacyclogenesis was demonstrated. In this study, we analysed the effect of glutamine analogues on the parasite life cycle. Here, we show that glutamine analogues impair cell proliferation, the developmental cycle during the infection of mammalian host cells and metacyclogenesis. Taken together, these results show that glutamine is an important metabolite for T. cruzi survival and suggest that glutamine analogues can be used as scaffolds for the development of new trypanocidal drugs. These data also reinforce the supposition that glutamine metabolism is an unexplored possible therapeutic target.

Identification of aTheileria annulataAntigen Expressed in Multiple Stages of the Parasite Life Cycle

1998 ◽  
Vol 90 (1) ◽  
pp. 110-121 ◽  
Author(s):  
P.A. Knight ◽  
S.W. Williamson ◽  
C.G.D. Brown ◽  
L. Bell-Sakyi ◽  
E. Kirvar ◽  
...  
Keyword(s):  
Life Cycle ◽  
Parasite Life Cycle ◽  
Multiple Stages

A multi-stage malaria vaccine candidate targeting both transmission and asexual parasite life-cycle stages

Vaccine ◽  
2014 ◽  
Vol 32 (22) ◽  
pp. 2623-2630 ◽  
Author(s):  
Michael Theisen ◽  
Will Roeffen ◽  
Susheel K. Singh ◽  
Gorm Andersen ◽  
Linda Amoah ◽  
...  
Keyword(s):  
Life Cycle ◽  
Malaria Vaccine ◽  
Vaccine Candidate ◽  
Asexual Parasite ◽  
Parasite Life Cycle ◽  
Life Cycle Stages ◽  
Multi Stage ◽  
Malaria Vaccine Candidate

scholarly journals Malaria vaccine development.

1994 ◽  
Vol 7 (3) ◽  
pp. 303-310 ◽  
Author(s):  
T R Jones ◽  
S L Hoffman
Keyword(s):  
Life Cycle ◽  
Vaccine Development ◽  
Host Cells ◽  
Host Immune System ◽  
Parasite Life Cycle ◽  
Liver Stage ◽  
Life Cycle Stages ◽  
Promising Area ◽  
The Right

The malaria parasite life cycle presents several targets for attack, but these different parts of the life cycle are susceptible to different types of host immune response. For example, the sporozoite is most sensitive to immune antibody, while liver stage parasites can be eliminated by cytotoxic T lymphocytes. Attachment of merozoites to erythrocytes, on the other hand, can be blocked by antibody. Convincing experimental evidence shows that completely protective immunity to malaria can be induced. The challenge now is to design recombinant or synthetic vaccines that induce the right types of immune responses to specific life cycle stages. This requires the identification and characterization of B- and T-lymphocyte epitopes expressed by the parasite or by parasitized host cells. These epitopes must be incorporated into a delivery system that maximizes the interaction between the vaccine epitopes and the host immune system. Many epitopes from several parts of the life cycle are already characterized; development of multivalent vaccines, that is, vaccines which contain immunogens from more than one part of the life cycle, is a promising area for research efforts.

#23: Investigation of Phosphomannomutase as an Antimalarial Drug Target

2021 ◽  
Vol 10 (Supplement_2) ◽  
pp. S10-S10
Author(s):  
Philip Frasse ◽  
Daniel Goldberg ◽  
Audrey Odom John
Keyword(s):  
Life Cycle ◽  
Metabolic Pathways ◽  
Drug Target ◽  
Large Family ◽  
Parasite Development ◽  
Parasite Life Cycle ◽  
Parasite Protein ◽  
Symptomatic Infection ◽  
Human Orthologs ◽  
Future Drug

Abstract Background Malaria continues to pose an enormous economic and global health threat, killing over 200,000 people annually, primarily children under the age of 5. With the constant barrier of antimalarial resistance and the rise of delayed clearance by artemisinin, it is especially important to identify drug/target pairs that rapidly kill parasites. We study targetable metabolic pathways in the malaria parasite, Plasmodium falciparum, to guide such future drug development against this disease. In recent years, we have discovered that a large family of hydrolases, the Haloacid Dehalogenase (HAD) Superfamily of proteins, are implicated in regulating a variety of P. falciparum metabolic pathways, which can lead to dramatic changes in central carbon metabolism and drug resistance. We now turn our attention to a related HAD protein, the putative phosphomannomutase in these parasites, HAD5, responsible for the interconversion of mannose-6-phosphate and mannose-1-phosphate. This is an essential process for all stages of the parasite, and thus has potential as a broad antimalarial target. We examined the role of HAD5 in these parasites, and its potential to be chemically inhibited. Methods Recombinant protein was generated and purified for enzymatic assays to determine HAD5 activity and test inhibitor potency against HAD5 compared to recombinant human orthologs, PMM1 and PMM2. In parallel, CRISPR/Cas9 was used to generate inducible knockdown parasite strains to demonstrate this gene’s essentiality and its role in parasite biology. Parasite growth was measured by flow cytometry and light microscopy. Immunofluorescence analysis (IFA) was used to track the parasite development on a molecular scale. Results Inhibition of HAD5 was achieved in biochemical assays, with an IC50 of 68µM in our most potent compound, representing roughly 10-fold increased potency against the parasite protein compared to human orthologs. In culture, knockdown of HAD5 leads to interrupted egress from and reinvasion into red blood cells, culminating in parasite death. In IFA-visualized parasites, reinvasion-facilitating proteins were no longer anchored to parasite surfaces, accounting for the inhibition of the parasite life cycle. Conclusion In the search for new antimalarial targets, identifying proteins that are essential across multiple parasite life-stages while being distinct from human orthologs is necessary to block parasite transmission, cure symptomatic infection, and minimize off-target effects. HAD5 is an essential protein in malaria parasites that is expressed throughout the parasite’s life cycle, and can be specifically targeted by inhibitors, giving it promise as a future drug target.

scholarly journals Identification and characterisation of a phospholipid scramblase in the malaria parasite Plasmodium falciparum

2020 ◽  
Author(s):  
Silvia Haase ◽  
Melanie Condron ◽  
David Miller ◽  
Dounia Cherkaoui ◽  
Sarah Jordan ◽  
...  
Keyword(s):  
Life Cycle ◽  
Metal Ion ◽  
Malaria Parasite ◽  
Gene Knockout ◽  
Parasite Development ◽  
Asexual Parasite ◽  
Parasite Life Cycle ◽  
Phospholipid Scramblase ◽  
Erythrocyte Invasion ◽  
Parasite Plasmodium Falciparum

AbstractRecent studies highlight the emerging role of lipids as important messengers in malaria parasite biology. In an attempt to identify interacting proteins and regulators of these dynamic and versatile molecules, we hypothesised the involvement of phospholipid translocases and their substrates in the infection of the host erythrocyte by the malaria parasite Plasmodium spp. Here, using a data base mining approach, we have identified a putative phospholipid (PL) scramblase in P. falciparum (PfPLSCR) that is conserved across the genus and in closely related unicellular algae. By reconstituting recombinant PfPLSCR into liposomes, we demonstrate metal ion dependent PL translocase activity and substrate preference, confirming PfPLSCR as a bona fide scramblase. We confirm that PfPLSCR is expressed during asexual and sexual parasite development, localising to different membranous compartments of the parasite throughout the intra-erythrocytic life cycle. Two different gene knockout approaches, however, suggest that PfPLSCR is not essential for erythrocyte invasion and asexual parasite development, pointing towards a possible role in other stages of the parasite life cycle.

scholarly journals Nucleosome Positioning on Episomal Human Papillomavirus DNA in Cultured Cells

Pathogens ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 772
Author(s):  
Isao Murakami ◽  
Takashi Iwata ◽  
Tohru Morisada ◽  
Kyoko Tanaka ◽  
Daisuke Aoki
Keyword(s):  
Life Cycle ◽  
Cultured Cells ◽  
Basal Layer ◽  
Nucleosome Positioning ◽  
Viral Life Cycle ◽  
Human Papillomaviruses ◽  
Host Cells ◽  
Micrococcal Nuclease ◽  
Hpv Dna ◽  
Dna Replication And Repair

Several human papillomaviruses (HPV) are associated with the development of cervical carcinoma. HPV DNA synthesis is increased during the differentiation of infected host keratinocytes as they migrate from the basal layer of the epithelium to the spinous layer, but the molecular mechanism is unclear. Nucleosome positioning affects various cellular processes such as DNA replication and repair by permitting the access of transcription factors to promoters to initiate transcription. In this study, nucleosome positioning on virus chromatin was investigated in normal immortalized keratinocytes (NIKS) stably transfected with HPV16 or HPV18 genomes to determine if there is an association with the viral life cycle. Micrococcal nuclease-treated DNA analyzed by Southern blotting using probes against HPV16 and HPV18 and quantified by nucleosome scanning analysis using real-time PCR revealed mononucleosomal-sized fragments of 140–200 base pairs that varied in their location within the viral genome according to whether the cells were undergoing proliferation or differentiation. Notably, changes in the regions around nucleotide 110 in proliferating and differentiating host cells were common to HPV16 and HPV18. Our findings suggest that changes in nucleosome positions on viral DNA during host cell differentiation is an important regulatory event in the viral life cycle.

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