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1.
PLoS One ; 19(7): e0305207, 2024.
Article in English | MEDLINE | ID: mdl-38968330

ABSTRACT

Increasing reports of insecticide resistance continue to hamper the gains of vector control strategies in curbing malaria transmission. This makes identifying new insecticide targets or alternative vector control strategies necessary. CLassifier of Essentiality AcRoss EukaRyote (CLEARER), a leave-one-organism-out cross-validation machine learning classifier for essential genes, was used to predict essential genes in Anopheles gambiae and selected predicted genes experimentally validated. The CLEARER algorithm was trained on six model organisms: Caenorhabditis elegans, Drosophila melanogaster, Homo sapiens, Mus musculus, Saccharomyces cerevisiae and Schizosaccharomyces pombe, and employed to identify essential genes in An. gambiae. Of the 10,426 genes in An. gambiae, 1,946 genes (18.7%) were predicted to be Cellular Essential Genes (CEGs), 1716 (16.5%) to be Organism Essential Genes (OEGs), and 852 genes (8.2%) to be essential as both OEGs and CEGs. RNA interference (RNAi) was used to validate the top three highly expressed non-ribosomal predictions as probable vector control targets, by determining the effect of these genes on the survival of An. gambiae G3 mosquitoes. In addition, the effect of knockdown of arginase (AGAP008783) on Plasmodium berghei infection in mosquitoes was evaluated, an enzyme we computationally inferred earlier to be essential based on chokepoint analysis. Arginase and the top three genes, AGAP007406 (Elongation factor 1-alpha, Elf1), AGAP002076 (Heat shock 70kDa protein 1/8, HSP), AGAP009441 (Elongation factor 2, Elf2), had knockdown efficiencies of 91%, 75%, 63%, and 61%, respectively. While knockdown of HSP or Elf2 significantly reduced longevity of the mosquitoes (p<0.0001) compared to control groups, Elf1 or arginase knockdown had no effect on survival. However, arginase knockdown significantly reduced P. berghei oocytes counts in the midgut of mosquitoes when compared to LacZ-injected controls. The study reveals HSP and Elf2 as important contributors to mosquito survival and arginase as important for parasite development, hence placing them as possible targets for vector control.


Subject(s)
Anopheles , Malaria , Mosquito Vectors , RNA Interference , Animals , Anopheles/genetics , Anopheles/parasitology , Malaria/prevention & control , Malaria/transmission , Malaria/parasitology , Mosquito Vectors/genetics , Mosquito Vectors/parasitology , Computational Biology/methods , Mice , Humans , Mosquito Control/methods , Genes, Essential , Female , Plasmodium berghei/genetics
2.
Nat Commun ; 15(1): 4697, 2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38824128

ABSTRACT

Differentiation of male gametocytes into flagellated fertile male gametes relies on the assembly of axoneme, a major component of male development for mosquito transmission of the malaria parasite. RNA-binding protein (RBP)-mediated post-transcriptional regulation of mRNA plays important roles in eukaryotic sexual development, including the development of female Plasmodium. However, the role of RBP in defining the Plasmodium male transcriptome and its function in male gametogenesis remains incompletely understood. Here, we performed genome-wide screening for gender-specific RBPs and identified an undescribed male-specific RBP gene Rbpm1 in the Plasmodium. RBPm1 is localized in the nucleus of male gametocytes. RBPm1-deficient parasites fail to assemble the axoneme for male gametogenesis and thus mosquito transmission. RBPm1 interacts with the spliceosome E complex and regulates the splicing initiation of certain introns in a group of 26 axonemal genes. RBPm1 deficiency results in intron retention and protein loss of these axonemal genes. Intron deletion restores axonemal protein expression and partially rectifies axonemal defects in RBPm1-null gametocytes. Further splicing assays in both reporter and endogenous genes exhibit stringent recognition of the axonemal introns by RBPm1. The splicing activator RBPm1 and its target introns constitute an axonemal intron splicing program in the post-transcriptional regulation essential for Plasmodium male development.


Subject(s)
Axoneme , Introns , Protozoan Proteins , RNA Splicing , RNA-Binding Proteins , Introns/genetics , RNA-Binding Proteins/metabolism , RNA-Binding Proteins/genetics , Animals , Protozoan Proteins/genetics , Protozoan Proteins/metabolism , Male , Axoneme/metabolism , Female , Gametogenesis/genetics , Spliceosomes/metabolism , Spliceosomes/genetics , Plasmodium berghei/genetics , Plasmodium berghei/growth & development , Plasmodium berghei/metabolism , Malaria/parasitology , Plasmodium/genetics , Plasmodium/metabolism
3.
J Cell Sci ; 137(11)2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38832798

ABSTRACT

Plasmodium sporozoites are the infective forms of the malaria parasite in the mosquito and vertebrate host. Gliding motility allows sporozoites to migrate and invade mosquito salivary glands and mammalian hosts. Motility and invasion are powered by an actin-myosin motor complex linked to the glideosome, which contains glideosome-associated proteins (GAPs), MyoA and the myosin A tail-interacting protein (MTIP). However, the role of several proteins involved in gliding motility remains unknown. We identified that the S14 gene is upregulated in sporozoite from transcriptome data of Plasmodium yoelii and further confirmed its transcription in P. berghei sporozoites using real-time PCR. C-terminal 3×HA-mCherry tagging revealed that S14 is expressed and localized on the inner membrane complex of the sporozoites. We disrupted S14 in P. berghei and demonstrated that it is essential for sporozoite gliding motility, and salivary gland and hepatocyte invasion. The gliding and invasion-deficient S14 knockout sporozoites showed normal expression and organization of inner membrane complex and surface proteins. Taken together, our data show that S14 plays a role in the function of the glideosome and is essential for malaria transmission.


Subject(s)
Malaria , Plasmodium berghei , Protozoan Proteins , Sporozoites , Sporozoites/metabolism , Plasmodium berghei/metabolism , Plasmodium berghei/genetics , Protozoan Proteins/metabolism , Protozoan Proteins/genetics , Animals , Mice , Malaria/parasitology , Salivary Glands/parasitology , Salivary Glands/metabolism , Anopheles/parasitology
4.
PLoS Negl Trop Dis ; 18(6): e0012231, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38865344

ABSTRACT

BACKGROUND: Malaria transmission-blocking vaccines (TBVs) aim to inhibit malaria parasite development in mosquitoes and prevent further transmission to the human host. The putative-secreted ookinete protein 25 (PSOP25), highly conserved in Plasmodium spp., is a promising TBV target. Here, we investigated PvPSOP25 from P. vivax as a TBV candidate using transgenic murine parasite P. berghei and clinical P. vivax isolates. METHODS AND FINDINGS: A transgenic P. berghei line expressing PvPSOP25 (TrPvPSOP25Pb) was generated. Full-length PvPSOP25 was expressed in the yeast Pichia pastoris and used to immunize mice to obtain anti-rPvPSOP25 sera. The transmission-blocking activity of the anti-rPvPSOP25 sera was evaluated through in vitro assays and mosquito-feeding experiments. The antisera generated by immunization with rPvPSOP25 specifically recognized the native PvPSOP25 antigen expressed in TrPvPSOP25Pb ookinetes. In vitro assays showed that the immune sera significantly inhibited exflagellation and ookinete formation of the TrPvPSOP25Pb parasite. Mosquitoes feeding on mice infected with the transgenic parasite and passively transferred with the anti-rPvPSOP25 sera showed a 70.7% reduction in oocyst density compared to the control group. In a direct membrane feeding assay conducted with five clinical P. vivax isolates, the mouse anti-rPvPSOP25 antibodies significantly reduced the oocyst density while showing a negligible influence on mosquito infection prevalence. CONCLUSIONS: This study supported the feasibility of transgenic murine malaria parasites expressing P. vivax antigens as a useful tool for evaluating P. vivax TBV candidates. Meanwhile, the moderate transmission-reducing activity of the generated anti-rPvPSOP25 sera necessitates further research to optimize its efficacy.


Subject(s)
Malaria Vaccines , Malaria, Vivax , Plasmodium berghei , Plasmodium vivax , Protozoan Proteins , Animals , Mice , Plasmodium vivax/genetics , Plasmodium vivax/immunology , Malaria Vaccines/immunology , Malaria Vaccines/administration & dosage , Plasmodium berghei/genetics , Plasmodium berghei/immunology , Protozoan Proteins/genetics , Protozoan Proteins/immunology , Humans , Malaria, Vivax/transmission , Malaria, Vivax/parasitology , Malaria, Vivax/prevention & control , Malaria, Vivax/immunology , Female , Antigens, Protozoan/genetics , Antigens, Protozoan/immunology , Antibodies, Protozoan/blood , Antibodies, Protozoan/immunology , Malaria/transmission , Malaria/prevention & control , Malaria/parasitology , Malaria/immunology , Mice, Inbred BALB C
5.
ACS Infect Dis ; 10(6): 1904-1913, 2024 Jun 14.
Article in English | MEDLINE | ID: mdl-38752809

ABSTRACT

Malaria parasites have a complex life cycle and undergo replication and population expansion within vertebrate hosts and mosquito vectors. These developmental transitions rely on changes in gene expression and chromatin reorganization that result in the activation and silencing of stage-specific genes. The ApiAp2 family of DNA-binding proteins plays an important role in regulating gene expression in malaria parasites. Here, we characterized the ApiAp2 protein in Plasmodium berghei, which we termed Ap2-D. In silico analysis revealed that Ap2-D has three beta-sheets followed by a helix at the C-terminus for DNA binding. Using gene tagging with 3XHA-mCherry, we found that Ap2-D is expressed in Plasmodium blood stages and is present in the parasite cytoplasm and nucleus. Surprisingly, our gene deletion study revealed a completely dispensable role for Ap2-D in the entirety of the P. berghei life cycle. Ap2-D KO parasites were found to grow in the blood successfully and progress through the mosquito midgut and salivary glands. Sporozoites isolated from mosquito salivary glands were infective for hepatocytes and achieved similar patency as WT in mice. We emphasize the importance of genetic validation of antimalarial drug targets before progressing them to drug discovery.


Subject(s)
Life Cycle Stages , Plasmodium berghei , Protozoan Proteins , Plasmodium berghei/genetics , Plasmodium berghei/growth & development , Plasmodium berghei/metabolism , Animals , Mice , Protozoan Proteins/genetics , Protozoan Proteins/metabolism , Malaria/parasitology , Transcription Factors/genetics , Transcription Factors/metabolism , Sporozoites/growth & development , Sporozoites/metabolism , Sporozoites/physiology , Salivary Glands/parasitology , Mosquito Vectors/parasitology , Female , Anopheles/parasitology , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Hepatocytes/parasitology
6.
Mol Microbiol ; 121(6): 1095-1111, 2024 06.
Article in English | MEDLINE | ID: mdl-38574236

ABSTRACT

The protozoan parasite Plasmodium, the causative agent of malaria, undergoes an obligatory stage of intra-hepatic development before initiating a blood-stage infection. Productive invasion of hepatocytes involves the formation of a parasitophorous vacuole (PV) generated by the invagination of the host cell plasma membrane. Surrounded by the PV membrane (PVM), the parasite undergoes extensive replication. During intracellular development in the hepatocyte, the parasites provoke the Plasmodium-associated autophagy-related (PAAR) response. This is characterized by a long-lasting association of the autophagy marker protein, and ATG8 family member, LC3B with the PVM. LC3B localization at the PVM does not follow the canonical autophagy pathway since upstream events specific to canonical autophagy are dispensable. Here, we describe that LC3B localization at the PVM of Plasmodium parasites requires the V-ATPase and its interaction with ATG16L1. The WD40 domain of ATG16L1 is crucial for its recruitment to the PVM. Thus, we provide new mechanistic insight into the previously described PAAR response targeting Plasmodium liver stage parasites.


Subject(s)
Autophagy-Related Proteins , Autophagy , Hepatocytes , Liver , Microtubule-Associated Proteins , Plasmodium berghei , Vacuolar Proton-Translocating ATPases , Vacuoles , Vacuoles/metabolism , Vacuoles/parasitology , Plasmodium berghei/genetics , Plasmodium berghei/growth & development , Plasmodium berghei/metabolism , Plasmodium berghei/enzymology , Animals , Autophagy-Related Proteins/metabolism , Autophagy-Related Proteins/genetics , Microtubule-Associated Proteins/metabolism , Microtubule-Associated Proteins/genetics , Liver/parasitology , Mice , Hepatocytes/parasitology , Vacuolar Proton-Translocating ATPases/metabolism , Vacuolar Proton-Translocating ATPases/genetics , Malaria/parasitology , Protozoan Proteins/metabolism , Protozoan Proteins/genetics , Humans
7.
Curr Opin Microbiol ; 79: 102469, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38574448

ABSTRACT

Malaria blood stage parasites commit to either one of two distinct cellular fates while developing within erythrocytes of their mammalian host: they either undergo another round of asexual replication or they differentiate into nonreplicative transmissible gametocytes. Depending on the state of infection, either path may support or impair the ultimate goal of human-to-human transmission via the mosquito vector. Malaria parasites therefore evolved strategies to control investments into asexual proliferation versus gametocyte formation. Recent work provided fascinating molecular insight into shared and unique mechanisms underlying the control and environmental modulation of sexual commitment in the two most widely studied malaria parasite species, Plasmodium falciparum and P. berghei. With this review, we aim at placing these findings into a comparative mechanistic context.


Subject(s)
Plasmodium berghei , Plasmodium falciparum , Plasmodium falciparum/physiology , Plasmodium falciparum/growth & development , Plasmodium falciparum/genetics , Animals , Humans , Plasmodium berghei/physiology , Plasmodium berghei/growth & development , Plasmodium berghei/genetics , Malaria/parasitology , Malaria/transmission , Erythrocytes/parasitology
8.
Malar J ; 23(1): 114, 2024 Apr 20.
Article in English | MEDLINE | ID: mdl-38643106

ABSTRACT

The use of fluorescent proteins (FPs) in Plasmodium parasites has been key to understand the biology of this obligate intracellular protozoon. FPs like the green fluorescent protein (GFP) enabled to explore protein localization, promoter activity as well as dynamic processes like protein export and endocytosis. Furthermore, FP biosensors have provided detailed information on physiological parameters at the subcellular level, and fluorescent reporter lines greatly extended the malariology toolbox. Still, in order to achieve optimal results, it is crucial to know exactly the properties of the FP of choice and the genetic scenario in which it will be used. This review highlights advantages and disadvantages of available landing sites and promoters that have been successfully applied for the ectopic expression of FPs in Plasmodium berghei and Plasmodium falciparum. Furthermore, the properties of newly developed FPs beyond DsRed and EGFP, in the visualization of cells and cellular structures as well as in the sensing of small molecules are discussed.


Subject(s)
Plasmodium berghei , Plasmodium falciparum , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Plasmodium berghei/genetics , Promoter Regions, Genetic , Plasmodium falciparum/genetics , Protein Transport
9.
Nucleic Acids Res ; 52(10): 5624-5642, 2024 Jun 10.
Article in English | MEDLINE | ID: mdl-38554111

ABSTRACT

Gametocyte development of the Plasmodium parasite is a key step for transmission of the parasite. Male and female gametocytes are produced from a subpopulation of asexual blood-stage parasites, but the mechanisms that regulate the differentiation of sexual stages are still under investigation. In this study, we investigated the role of PbARID, a putative subunit of a SWI/SNF chromatin remodeling complex, in transcriptional regulation during the gametocyte development of P. berghei. PbARID expression starts in early gametocytes before the manifestation of male and female-specific features, and disruption of its gene results in the complete loss of gametocytes with detectable male features and the production of abnormal female gametocytes. ChIP-seq analysis of PbARID showed that it forms a complex with gSNF2, an ATPase subunit of the SWI/SNF chromatin remodeling complex, associating with the male cis-regulatory element, TGTCT. Further ChIP-seq of PbARID in gsnf2-knockout parasites revealed an association of PbARID with another cis-regulatory element, TGCACA. RIME and DNA-binding assays suggested that HDP1 is the transcription factor that recruits PbARID to the TGCACA motif. Our results indicated that PbARID could function in two chromatin remodeling events and paly essential roles in both male and female gametocyte development.


Subject(s)
Chromatin Assembly and Disassembly , Plasmodium berghei , Protozoan Proteins , Transcription Factors , Animals , Female , Male , Mice , Chromatin Assembly and Disassembly/genetics , Plasmodium berghei/genetics , Plasmodium berghei/growth & development , Protozoan Proteins/genetics , Protozoan Proteins/metabolism , Transcription Factors/genetics , Transcription Factors/metabolism , Genotype , Sequence Analysis, RNA , Chromatin/genetics , Chromatin/metabolism , Amino Acid Sequence , Sequence Analysis, Protein , Phylogeny , Transcriptome , Genome, Protozoan
10.
J Infect Dis ; 229(6): 1894-1903, 2024 Jun 14.
Article in English | MEDLINE | ID: mdl-38408353

ABSTRACT

BACKGROUND: Plasmodium falciparum and Plasmodium vivax account for >90% global malaria burden. Transmission intervention strategies encompassing transmission-blocking vaccines (TBV) and drugs represent ideal public health tools to eliminate malaria at the population level. The availability of mature P. falciparum gametocytes through in vitro culture has facilitated development of a standard membrane feeding assay to assess efficacy of transmission interventions against P. falciparum. The lack of in vitro culture for P. vivax has significantly hampered similar progress on P. vivax and limited studies have been possible using blood from infected patients in endemic areas. The ethical and logistical limitations of on-time access to blood from patients have impeded the development of P. vivax TBVs. METHODS: Transgenic murine malaria parasites (Plasmodium berghei) expressing TBV candidates offer a promising alternative for evaluation of P. vivax TBVs through in vivo studies in mice, and ex vivo membrane feeding assay (MFA). RESULTS: We describe the development of transmission-competent transgenic TgPbvs25 parasites and optimization of parameters to establish an ex vivo MFA to evaluate P. vivax TBV based on Pvs25 antigen. CONCLUSIONS: The MFA is expected to expedite Pvs25-based TBV development without dependence on blood from P. vivax-infected patients in endemic areas for evaluation.


Subject(s)
Malaria Vaccines , Malaria, Vivax , Plasmodium berghei , Plasmodium vivax , Animals , Malaria Vaccines/immunology , Malaria Vaccines/genetics , Plasmodium vivax/genetics , Plasmodium vivax/immunology , Malaria, Vivax/transmission , Malaria, Vivax/prevention & control , Malaria, Vivax/parasitology , Plasmodium berghei/genetics , Plasmodium berghei/immunology , Mice , Antigens, Protozoan/immunology , Antigens, Protozoan/genetics , Humans , Female , Antigens, Surface
11.
Mol Microbiol ; 121(3): 565-577, 2024 03.
Article in English | MEDLINE | ID: mdl-38396332

ABSTRACT

Plasmodium sporozoites are the highly motile and invasive forms of the malaria parasite transmitted by mosquitoes. Sporozoites form within oocysts at the midgut wall of the mosquito, egress from oocysts and enter salivary glands prior to transmission. The GPI-anchored major surface protein, the circumsporozoite protein (CSP) is important for Plasmodium sporozoite formation, egress, migration and invasion. To visualize CSP, we previously generated full-length versions of CSP internally tagged with the green fluorescent protein, GFP. However, while these allowed for imaging of sporogony in oocysts, sporozoites failed to egress. Here, we explore different strategies to overcome this block in egress and obtain salivary gland resident sporozoites that express CSP-GFP. Replacing the N-terminal and repeat region with GFP did not allow sporozoite formation. Lowering expression of CSP-GFP at the endogenous locus allowed sporozoite formation but did not overcome egress block. Crossing of CSP-GFP expressing parasites that are blocked in egress with wild-type parasites yielded a small fraction of parasites that entered salivary glands and expressed various levels of CSP-GFP. Expressing CSP-GFP constructs from a silent chromosome region from promoters that are active only post salivary gland invasion yielded normal numbers of fluorescent salivary gland sporozoites, albeit with low levels of fluorescence. We also show that lowering CSP expression by 50% allowed egress from oocysts but not salivary gland entry. In conclusion, Plasmodium berghei parasites with normal CSP expression tolerate a certain level of CSP-GFP without disruption of oocyst egress and salivary gland invasion.


Subject(s)
Anopheles , Sporozoites , Animals , Sporozoites/metabolism , Protozoan Proteins/genetics , Protozoan Proteins/metabolism , Anopheles/parasitology , Oocysts , Plasmodium berghei/genetics , Plasmodium berghei/metabolism
12.
ACS Infect Dis ; 10(4): 1116-1125, 2024 04 12.
Article in English | MEDLINE | ID: mdl-38421807

ABSTRACT

The O-fucosylation of the thrombospondin type I repeat (TSR) domain is important for TSR-containing proteins' optimal folding and stability. However, the importance of Plasmodium O-fucosyltransferase 2 (POFut2) remains unclear due to two different reports. Here, we disrupted the POFut2 gene in Plasmodium berghei and demonstrated that POFut2 KO parasites develop normally in blood and mosquito stages but show reduced infectivity in mice. We found that the reduced infectivity of POFut2 KO sporozoites was due to a diminished level of TRAP that affected the parasite gliding motility and hepatocyte infectivity. Using all-atom MD simulation, we also hypothesize that O-fucosylation impacts the TSR domain's stability more than its heparin binding capacity.


Subject(s)
Fucosyltransferases , Plasmodium berghei , Animals , Mice , Fucosyltransferases/genetics , Fucosyltransferases/metabolism , Plasmodium berghei/genetics , Sporozoites , Protozoan Proteins/metabolism , Hepatocytes/parasitology
13.
Mol Microbiol ; 121(5): 940-953, 2024 05.
Article in English | MEDLINE | ID: mdl-38419272

ABSTRACT

Plasmodium is an obligate intracellular parasite that requires intense lipid synthesis for membrane biogenesis and survival. One of the principal membrane components is oleic acid, which is needed to maintain the membrane's biophysical properties and fluidity. The malaria parasite can modify fatty acids, and stearoyl-CoA Δ9-desaturase (Scd) is an enzyme that catalyzes the synthesis of oleic acid by desaturation of stearic acid. Scd is dispensable in P. falciparum blood stages; however, its role in mosquito and liver stages remains unknown. We show that P. berghei Scd localizes to the ER in the blood and liver stages. Disruption of Scd in the rodent malaria parasite P. berghei did not affect parasite blood stage propagation, mosquito stage development, or early liver-stage development. However, when Scd KO sporozoites were inoculated intravenously or by mosquito bite into mice, they failed to initiate blood-stage infection. Immunofluorescence analysis revealed that organelle biogenesis was impaired and merozoite formation was abolished, which initiates blood-stage infections. Genetic complementation of the KO parasites restored merozoite formation to a level similar to that of WT parasites. Mice immunized with Scd KO sporozoites confer long-lasting sterile protection against infectious sporozoite challenge. Thus, the Scd KO parasite is an appealing candidate for inducing protective pre-erythrocytic immunity and hence its utility as a GAP.


Subject(s)
Liver , Malaria , Merozoites , Organelle Biogenesis , Plasmodium berghei , Sporozoites , Stearoyl-CoA Desaturase , Plasmodium berghei/genetics , Plasmodium berghei/growth & development , Plasmodium berghei/metabolism , Plasmodium berghei/enzymology , Animals , Mice , Liver/parasitology , Merozoites/growth & development , Merozoites/metabolism , Malaria/parasitology , Stearoyl-CoA Desaturase/metabolism , Stearoyl-CoA Desaturase/genetics , Sporozoites/growth & development , Sporozoites/metabolism , Protozoan Proteins/metabolism , Protozoan Proteins/genetics , Anopheles/parasitology , Female , Endoplasmic Reticulum/metabolism
14.
mBio ; 15(4): e0023224, 2024 Apr 10.
Article in English | MEDLINE | ID: mdl-38411954

ABSTRACT

Neddylation is a type of posttranslational modification known to regulate a wide range of cellular processes by covalently conjugating the ubiquitin-like protein Nedd8 to target proteins at lysine residues. However, the role of neddylation in malaria parasites has not been determined. Here, for the first time, we showed that neddylation plays an essential role in malaria transmission in Plasmodium berghei. We found that disruption of Nedd8 did not affect blood-stage propagation, gametocyte development, gamete formation, or zygote formation while abolishing the formation of ookinetes and further transmission of the parasites in mosquitoes. These phenotypic defects in Nedd8 knockout parasites were complemented by reintroducing the gene that restored mosquito transmission to wild-type levels. Our data establish the role of P. berghei Nedd8 in malaria parasite transmission.IMPORTANCENeddylation is a process by which Nedd8 is covalently attached to target proteins through three-step enzymatic cascades. The attachment of Nedd8 residues results in a range of diverse functions, such as cell cycle regulation, metabolism, immunity, and tumorigenesis. The potential neddylation substrates are cullin (CUL) family members, which are implicated in controlling the cell cycle. Cullin neddylation leads to the activation of cullin-RING ubiquitin ligases, which regulate a myriad of biological processes through target-specific ubiquitylation. Neddylation possibly regulates meiosis in zygotes, which subsequently develop into ookinetes. Our findings point to an essential function of this neddylation pathway and highlight its possible importance in designing novel intervention strategies.


Subject(s)
Plasmodium berghei , Ubiquitins , Animals , Ubiquitins/genetics , Ubiquitins/metabolism , Plasmodium berghei/genetics , Plasmodium berghei/metabolism , Cullin Proteins/metabolism , Ubiquitin/metabolism , Ubiquitin-Protein Ligases/metabolism
15.
Malar J ; 23(1): 13, 2024 Jan 09.
Article in English | MEDLINE | ID: mdl-38195464

ABSTRACT

BACKGROUND: Plasmodium lacks an mRNA export receptor ortholog, such as yeast Mex67. Yeast Mex67 contains a nuclear transport factor 2 (NTF2)-like domain, suggesting that NTF2-like domain-containing proteins might be associated with mRNA export in Plasmodium. In this study, the relationship between mRNA export and an NTF2-like domain-containing protein, PBANKA_1019700, was investigated using the ANKA strain of rodent malaria parasite Plasmodium berghei. METHODS: The deletion mutant Δ1019700 was generated by introducing gene-targeting vectors into the P. berghei ANKA genome, and parasite growth and virulence were examined. To investigate whether PBANKA_1019700 is involved in mRNA export, live-cell fluorescence imaging and immunoprecipitation coupled to mass spectrometry (IP-MS) were performed using transgenic parasites expressing fusion proteins (1019700::mCherry). RESULTS: Deletion of PBANKA_1019700 affected the sexual phase but not the asexual phase of malaria parasites. Live-cell fluorescence imaging showed that PBANKA_1019700 localizes to the cytoplasm. Moreover, IP-MS analysis of 1019700::mCherry indicated that PBANKA_1019700 interacts with ubiquitin-related proteins but not nuclear proteins. CONCLUSIONS: PBANKA_1019700 is a noncanonical NTF2-like superfamily protein.


Subject(s)
Malaria , Plasmodium berghei , Humans , Plasmodium berghei/genetics , Active Transport, Cell Nucleus , Saccharomyces cerevisiae , RNA, Messenger
16.
Mol Microbiol ; 121(3): 394-412, 2024 03.
Article in English | MEDLINE | ID: mdl-37314965

ABSTRACT

Plasmodium parasites, the eukaryotic pathogens that cause malaria, feature three distinct invasive forms tailored to the host environment they must navigate and invade for life cycle progression. One conserved feature of these invasive forms is the micronemes, apically oriented secretory organelles involved in egress, motility, adhesion, and invasion. Here we investigate the role of GPI-anchored micronemal antigen (GAMA), which shows a micronemal localization in all zoite forms of the rodent-infecting species Plasmodium berghei. ∆GAMA parasites are severely defective for invasion of the mosquito midgut. Once formed, oocysts develop normally, however, sporozoites are unable to egress and exhibit defective motility. Epitope-tagging of GAMA revealed tight temporal expression late during sporogony and showed that GAMA is shed during sporozoite gliding motility in a similar manner to circumsporozoite protein. Complementation of P. berghei knockout parasites with full-length P. falciparum GAMA partially restored infectivity to mosquitoes, indicating conservation of function across Plasmodium species. A suite of parasites with GAMA expressed under the promoters of CTRP, CAP380, and TRAP, further confirmed the involvement of GAMA in midgut infection, motility, and vertebrate infection. These data show GAMA's involvement in sporozoite motility, egress, and invasion, implicating GAMA as a regulator of microneme function.


Subject(s)
Culicidae , Parasites , Animals , Culicidae/metabolism , Culicidae/parasitology , Parasites/metabolism , Protozoan Proteins/genetics , Protozoan Proteins/metabolism , Oocysts , Plasmodium berghei/genetics , Plasmodium berghei/metabolism , Sporozoites/metabolism
17.
Int J Parasitol ; 54(2): 99-107, 2024 Feb.
Article in English | MEDLINE | ID: mdl-37774810

ABSTRACT

The successful completion of gamete fertilization is essential for malaria parasite transmission, and this process can be targeted by intervention strategies. In this study, we identified a conserved gene (PBANKA_0813300) in the rodent malaria parasite Plasmodium berghei, which encodes a protein of 54 kDa (designated as Pbs54). Localization studies indicated that Pbs54 is associated with the plasma membranes of gametes and ookinetes. Functional studies by gene disruption showed that the Δpbs54 parasites had no defect in asexual proliferation, gametocyte development, or gametogenesis. However, the interactions between male and female gametes were significantly decreased compared with wild-type parasites. The Δpbs54 lines did not show a further reduction in zygote and ookinete numbers during in vitro culture, indicating that the defects were probably restricted to gamete fertilization. Consistent with this finding, mosquitoes fed on Δpbs54-infected mice showed a 30.1% reduction in infection prevalence and a 74.7% reduction in oocyst intensity. Cross-fertilization assay indicated that both male and female gametes were impaired in the Δpbs54 parasites. To evaluate its transmission-blocking potential, we obtained polyclonal antibodies from mice immunized with the recombinant Pbs54 (rPbs54) protein. In vitro assays showed that anti-rPbs54 sera inhibited ookinete formation by 42.7%. Our experiments identified Pbs54 as a fertility factor required for mosquito transmission and a novel candidate for a malaria transmission-blocking vaccine.


Subject(s)
Culicidae , Malaria Vaccines , Malaria , Animals , Female , Male , Mice , Antibodies, Protozoan , Fertilization , Germ Cells , Malaria/prevention & control , Membrane Proteins/genetics , Plasmodium berghei/genetics , Plasmodium berghei/metabolism , Protozoan Proteins/metabolism , Recombinant Proteins
18.
Mol Microbiol ; 121(3): 481-496, 2024 03.
Article in English | MEDLINE | ID: mdl-38009402

ABSTRACT

Plasmodium sporozoite development in and egress from oocysts in the Anopheles mosquito remains largely enigmatic. In a previously performed high-throughput knockout screen, the putative subunit 5 of the prefoldin complex (PbPCS5, PBANKA_0920100) was identified as essential for parasite development during mosquito and liver stage development. Here we generated and analyzed a PbPCS5 knockout parasite line during its development in the mosquito. Interestingly, PbPCS5 deletion does not significantly affect oocyst formation but leads to a growth defect resulting in aberrantly shaped sporozoites. Sporozoites produced in the absence of PbPCS5 were thinner, markedly elongated, and did, in most cases, not contain a nucleus. Sporozoites contained fewer subpellicular microtubules, which reached deep into the sporoblast during sporogony where they contacted and indented nuclei. These aberrantly shaped sporozoites did not reach the salivary glands, and we, therefore, conclude that PbPCS5 is essential for sporogony and the life cycle progression of the parasite during its mosquito stage.


Subject(s)
Anopheles , Molecular Chaperones , Parasites , Animals , Plasmodium berghei/genetics , Oocysts , Sporozoites , Anopheles/parasitology , Protozoan Proteins/genetics , Microtubules
19.
Nat Commun ; 14(1): 8263, 2023 Dec 13.
Article in English | MEDLINE | ID: mdl-38092766

ABSTRACT

Gametogenesis in Plasmodium spp. occurs within the Anopheles mosquito and is essential for sexual reproduction / differentiation and onwards transmission to mammalian hosts. To better understand the 3D organisation of male gametogenesis, we used serial block face scanning electron microscopy (SBF-SEM) and serial-section cellular electron tomography (ssET) of P. berghei microgametocytes to examine key structures during male gamete formation. Our data reveals an elaborate organisation of axonemes coiling around the nucleus in opposite directions forming a central axonemal band in microgametocytes. Furthermore, we discover the nucleus of microgametes to be tightly coiled around the axoneme in a complex structure whose formation starts before microgamete emergence during exflagellation. Our discoveries of the detailed 3D organisation of the flagellated microgamete and the haploid genome highlight some of the atypical mechanisms of axoneme assembly and haploid genome organisation during male gamete formation in the malaria parasite.


Subject(s)
Anopheles , Plasmodium berghei , Male , Animals , Plasmodium berghei/genetics , Haploidy , Germ Cells , Anopheles/parasitology , Flagella/genetics , Mammals
20.
Elife ; 122023 Dec 05.
Article in English | MEDLINE | ID: mdl-38051195

ABSTRACT

Lipophorin is an essential, highly expressed lipid transport protein that is secreted and circulates in insect hemolymph. We hijacked the Anopheles coluzzii Lipophorin gene to make it co-express a single-chain version of antibody 2A10, which binds sporozoites of the malaria parasite Plasmodium falciparum. The resulting transgenic mosquitoes show a markedly decreased ability to transmit Plasmodium berghei expressing the P. falciparum circumsporozoite protein to mice. To force the spread of this antimalarial transgene in a mosquito population, we designed and tested several CRISPR/Cas9-based gene drives. One of these is installed in, and disrupts, the pro-parasitic gene Saglin and also cleaves wild-type Lipophorin, causing the anti-malarial modified Lipophorin version to replace the wild type and hitch-hike together with the Saglin drive. Although generating drive-resistant alleles and showing instability in its gRNA-encoding multiplex array, the Saglin-based gene drive reached high levels in caged mosquito populations and efficiently promoted the simultaneous spread of the antimalarial Lipophorin::Sc2A10 allele. This combination is expected to decrease parasite transmission via two different mechanisms. This work contributes to the design of novel strategies to spread antimalarial transgenes in mosquitoes, and illustrates some expected and unexpected outcomes encountered when establishing a population modification gene drive.


Subject(s)
Anopheles , Antimalarials , Gene Drive Technology , Lipoproteins , Animals , Mice , Anopheles/genetics , Anopheles/parasitology , Antimalarials/pharmacology , Mosquito Vectors/genetics , RNA, Guide, CRISPR-Cas Systems , Plasmodium falciparum/genetics , Plasmodium berghei/genetics
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