Clone 3D7 Research Articles

Molecular survey of pfmdr-1, pfcrt, and pfk13 gene mutations among patients returning from Plasmodium falciparum endemic areas to Turkey

BackgroundIn recent years, there has been an increasing trend in the number of imported Plasmodium falciparum cases in Turkey. To improve treatment success and to better understand malaria epidemiology among imported cases, it is necessary to determine anti-malarial drug resistance. This study aimed to survey polymorphisms of resistance genes in imported P. falciparum patients using archived thin smear preparations and EDTA blood samples.MethodsA total of 100 imported P. falciparum patients admitted to Bakırköy Dr. Sadi Konuk Research and Training Hospital between 2017 and 2022 were included in this study. DNA extraction was performed using an archived slide and EDTA blood samples that were microscopically diagnosed. After confirming the samples by real-time PCR, the pfmdr1, pfcrt, and pfk13 genes were amplified and sequenced. Single nucleotide polymorphisms (SNPs) were screened using Geneious R9 software, with the reference P. falciparum clone 3D7 isolate.ResultsAll studied samples were confirmed to be P. falciparum using real-time PCR. Nested PCR was conducted and the pfcrt (92 samples), pfmdr1 (91 samples), and pfk13 (93 samples) genes were successfully amplified. Sequence analysis revealed the highest mutation rate in the pfmdr1 (74.5%) gene, with the identification of five haplotypes: NYSND (wild-type, 23%), NFSND (56%), NYSDD (2.2%), NFSDD (15.4%), and YFSND (3.4%)]. The pfcrt mutation was identified in 11 samples (12.2%), whereas the pfk13 mutation was found in only two samples.ConclusionThis study is the first molecular survey of anti-malarial drug resistance genes in Turkey. With the increasing number of imported Plasmodium malaria cases and recent reports of sporadic indigenous P. falciparum cases, malaria is becoming a growing concern in Turkey. Although molecular screening for resistance markers in P. falciparum malaria is not routinely conducted, the data from this study will enhance treatment success rates and contribute to global malaria elimination.

Isoliensinine from Cissampelos pariera rhizomes exhibits potential gametocytocidal and anti-malarial activities against Plasmodium falciparum clinical isolates

BackgroundThe unmet demand for effective malaria transmission-blocking agents targeting the transmissible stages of Plasmodium necessitates intensive discovery efforts. In this study, a bioactive bisbenzylisoquinoline (BBIQ), isoliensinine, from Cissampelos pariera (Menispermaceae) rhizomes was identified and characterized for its anti-malarial activity.MethodsMalaria SYBR Green I fluorescence assay was performed to evaluate the in vitro antimalarial activity against D6, Dd2, and F32-ART5 clones, and immediate ex vivo (IEV) susceptibility for 10 freshly collected P. falciparum isolates. To determine the speed- and stage-of-action of isoliensinine, an IC50 speed assay and morphological analyses were performed using synchronized Dd2 asexuals. Gametocytocidal activity against two culture-adapted gametocyte-producing clinical isolates was determined using microscopy readouts, with possible molecular targets and their binding affinities deduced in silico.ResultsIsoliensinine displayed a potent in vitro gametocytocidal activity at mean IC50gam values ranging between 0.41 and 0.69 µM for Plasmodium falciparum clinical isolates. The BBIQ compound also inhibited asexual replication at mean IC50Asexual of 2.17 µM, 2.22 µM, and 2.39 µM for D6, Dd2 and F32-ART5 respectively, targeting the late-trophozoite to schizont transition. Further characterization demonstrated a considerable immediate ex vivo potency against human clinical isolates at a geometric mean IC50IEV = 1.433 µM (95% CI 0.917–2.242). In silico analyses postulated a probable anti-malarial mechanism of action by high binding affinities for four mitotic division protein kinases; Pfnek1, Pfmap2, Pfclk1, and Pfclk4. Additionally, isoliensinine was predicted to possess an optimal pharmacokinetics profile and drug-likeness properties.ConclusionThese findings highlight considerable grounds for further exploration of isoliensinine as an amenable scaffold for malaria transmission-blocking chemistry and target validation.

Molecular surveillance of Kelch-13 gene in Plasmodium falciparum field isolates from Mayurbhanj District, Odisha, India, and in silico artemisinin-Kelch-13 protein interaction study.

The global malaria control and elimination program faces major threats due to the emergence and transmission of the anti-malarial drug-resistant strain of Plasmodium falciparum. Monitoring of artemisinin (ART) resistance marker Kelch-13 in the malaria-endemic region is essential in mitigating the disease's morbidity and mortality. The current study aimed to generate baseline information for further surveillance in the future. The current research was designed and conducted from July 2019 to June 2021 to monitor Pfkelch13 mutation at the molecular level in the eastern region of India. We also conducted an in silico study to understand the drug-protein interactions between ART and the protein crystal of PfKelch13 (KELCH) with PDB id:4ZGC. The kelch-13 gene was amplified by nested polymerase chain reaction (PCR) and sequenced through the Sanger sequencing method. Reference 3D7 clone (PF3D7_1343700) was used to align and probe all the sequences. The sequence analysis showed the absence of validated or associated mutation in the Kelch-13 propeller domain. The absence of natural selection in drug resistance was confirmed by the Tajima test. Further, in silico interaction studies between the drug ART and the Kelch propeller domain of P. falciparum were evaluated by structure predictions, molecular docking, molecular dynamics (MD) simulations, and estimations of binding free energies for the KELCH-ART complex. The results were compared with the apoprotein (KELCH-APO). The study confirmed the favorable binding of ART with the Kelch-13 propeller domain.

A Malaria Parasite Cross Reveals Genetic Determinants of Plasmodium falciparum Growth in Different Culture Media.

What genes determine in vitro growth and nutrient utilization in asexual blood-stage malaria parasites? Competition experiments between NF54, clone 3D7, a lab-adapted African parasite, and a recently isolated Asian parasite (NHP4026) reveal contrasting outcomes in different media: 3D7 outcompetes NHP4026 in media containing human serum, while NHP4026 outcompetes 3D7 in media containing AlbuMAX, a commercial lipid-rich bovine serum formulation. To determine the basis for this polymorphism, we conducted parasite genetic crosses using humanized mice and compared genome-wide allele frequency changes in three independent progeny populations cultured in media containing human serum or AlbuMAX. This bulk segregant analysis detected three quantitative trait loci (QTL) regions [on chromosome (chr) 2 containing aspartate transaminase AST; chr 13 containing EBA-140; and chr 14 containing cysteine protease ATG4] linked with differential growth in serum or AlbuMAX in each of the three independent progeny pools. Selection driving differential growth was strong (s = 0.10 – 0.23 per 48-hour lifecycle). We conducted validation experiments for the strongest QTL on chr 13: competition experiments between ΔEBA-140 and 3D7 wildtype parasites showed fitness reversals in the two medium types as seen in the parental parasites, validating this locus as the causative gene. These results (i) demonstrate the effectiveness of bulk segregant analysis for dissecting fitness traits in P. falciparum genetic crosses, and (ii) reveal intimate links between red blood cell invasion and nutrient composition of growth media. Use of parasite crosses combined with bulk segregant analysis will allow systematic dissection of key nutrient acquisition/metabolism and red blood cell invasion pathways in P. falciparum.

Comprehensive BCMA Expression Profiling in Adult Normal Human Brain Suggests a Low Risk of On-target Neurotoxicity in BCMA-targeting Multiple Myeloma Therapy.

B-cell maturation antigen (BCMA) is a target for the treatment of multiple myeloma with cytolytic therapies, such as chimeric antigen receptor T-cells or T-cell redirecting antibodies. To better understand the potential for "on-target/off-tumor" toxicity caused by BCMA-targeting cytolytic therapies in the brain, we investigated normal brain BCMA expression. An immunohistochemistry (IHC) assay using the E6D7B commercial monoclonal antibody was applied to 107 formalin-fixed, paraffin-embedded brain samples (cerebrum, basal ganglia, cerebellum, brainstem; 63 unique donors). Although immunoreactivity was observed in a small number of neurons in brain regions including the striatum, thalamus, midbrain, and medulla, this immunoreactivity was considered nonspecific and not reflective of BCMA expression because it was distinct from the membranous and Golgi-like pattern seen in positive control samples, was not replicated when a different IHC antibody (D6 clone) was used, and was not corroborated by in situ hybridization data. Analysis of RNA-sequencing data from 478 donors in the GTEx and Allen BrainSpan databases demonstrated low levels of BCMA RNA expression in the striatum of young donors with levels becoming negligible beyond 30 years of age. We concluded that BCMA protein is not present in normal adult human brain, and therefore on-target toxicity in the brain is unlikely.

APC-Targeted DNA Vaccination Against Reticulocyte-Binding Protein Homolog 5 Induces Plasmodium falciparum-Specific Neutralizing Antibodies and T Cell Responses.

Targeted delivery of antigen to antigen presenting cells (APCs) is an efficient way to induce robust antigen-specific immune responses. Here, we present a novel DNA vaccine that targets the Plasmodium falciparum reticulocyte-binding protein homolog 5 (PfRH5), a leading blood-stage antigen of the human malaria pathogen, to APCs. The vaccine is designed as bivalent homodimers where each chain is composed of an amino-terminal single chain fragment variable (scFv) targeting unit specific for major histocompatibility complex class II (MHCII) expressed on APCs, and a carboxyl-terminal antigenic unit genetically linked by the dimerization unit. This vaccine format, named “Vaccibody”, has previously been successfully applied for antigens from other infectious diseases including influenza and HIV, as well as for tumor antigens. Recently, the crystal structure and key functional antibody epitopes for the truncated version of PfRH5 (PfRH5ΔNL) were characterized, suggesting PfRH5ΔNL to be a promising candidate for next-generation PfRH5 vaccine design. In this study, we explored the APC-targeting strategy for a PfRH5ΔNL-containing DNA vaccine. BALB/c mice immunized with the targeted vaccine induced higher PfRH5-specific IgG1 antibody responses than those vaccinated with a non-targeted vaccine or antigen alone. The APC-targeted vaccine also efficiently induced rapid IFN-γ and IL-4 T cell responses. Furthermore, the vaccine-induced PfRH5-specific IgG showed inhibition of growth of the P. falciparum 3D7 clone parasite in vitro. Finally, sera obtained after vaccination with this targeted vaccine competed for the same epitopes as PfRH5-specific mAbs from vaccinated humans. Robust humoral responses were also induced by a similar P. vivax Duffy-binding protein (PvDBP)-containing targeted DNA vaccine. Our data highlight a novel targeted vaccine platform for the development of vaccines against blood-stage malaria.

A portfolio of geographically distinct laboratory-adapted Plasmodium falciparum clones with consistent infection rates in Anopheles mosquitoes

BackgroundThe ability to culture Plasmodium falciparum continuously in vitro has enabled stable access to asexual and sexual parasites for malaria research. The portfolio of isolates has remained limited and research is still largely based on NF54 and its derived clone 3D7. Since 1978, isolates were collected and cryopreserved at Radboudumc from patients presenting at the hospital. Here, procedures are described for culture adaptation of asexual parasites, cloning and production of sexual stage parasites responsible for transmission (gametocytes) and production of oocysts in Anopheles mosquitoes. This study aimed to identify new culture-adapted transmissible P. falciparum isolates, originating from distinct geographical locations.MethodsOut of a collection of 121 P. falciparum isolates stored in liquid nitrogen, 21 from different geographical origin were selected for initial testing. Isolates were evaluated for their ability to be asexually cultured in vitro, their gametocyte production capacity, and consistent generation of oocysts.ResultsOut of 21 isolates tested, twelve were excluded from further analysis due to lack of mature gametocyte production (n = 1) or generation of satisfactory numbers of oocysts in mosquitoes (n = 11). Nine isolates fulfilled selection criteria and were cloned by limiting dilution and retested. After cloning, one isolate was excluded for not showing transmission. The remaining eight isolates transmitted to Anopheles stephensi or Anopheles coluzzii mosquitoes and were categorized into two groups with a reproducible mean oocyst infection intensity above (n = 5) or below five (n = 3).ConclusionsThese new P. falciparum culture-adapted isolates with reproducible transmission to Anopheles mosquitoes are a valuable addition to the malaria research tool box. They can aid in the development of malaria interventions and will be particularly useful for those studying malaria transmission.

Comparative analysis of the ex vivo IFN-gamma responses to CD8+ T cell epitopes within allelic forms of PfAMA1 in subjects with natural exposure to malaria.

Antigen polymorphisms in essential malarial antigens are a key challenge to the design and development of broadly effective malaria vaccines. The effect of polymorphisms on antibody responses is fairly well studied while much fewer studies have assessed this for T cell responses. This study investigated the effect of allelic polymorphisms in the malarial antigen apical membrane antigen 1 (AMA1) on ex vivo T cell-specific IFN-γ responses in subjects with lifelong exposure to malaria. Human leukocyte antigen (HLA) class I-restricted peptides from the 3D7 clone AMA1 were bioinformatically predicted and those with variant amino acid positions used to select corresponding allelic sequences from the 7G8, FVO, FC27 and tm284 parasite strains. A total of 91 AMA1 9-10mer peptides from the five parasite strains were identified, synthesized, grouped into 42 allele sets and used to stimulate PBMCs from seven HLA class 1-typed subjects in IFN-γ ELISpot assays. PBMCs from four of the seven subjects (57%) made positive responses to 18 peptides within 12 allele sets. Fifty percent of the 18 positive peptides were from the 3D7 parasite variant. Amino acid substitutions that were associated with IFN-γ response abrogation were more frequently found at positions 1 and 6 of the tested peptides, but substitutions did not show a clear pattern of association with response abrogation. Thus, while we show some evidence of polymorphisms affecting T cell response induction, other factors including TCR recognition of HLA-peptide complexes may also be at play.

B- Cell Maturation Antigen Is Exclusively Expressed in a Wide Range of B-Cell and Plasma Cell Neoplasm and in a Potential Therapeutic Target for Bcma Directed Therapies

Background: BCMA (TNFRSF17 or CD269) is a cell surface protein expressed on a subset of B cells and mature plasma cells. It is related to BAFF receptor, transmembrane activator, calcium modulator and cyclophilin ligand interactor (TACI). When engaged by their ligands APRIL and BAFF these three receptors induce B cell maturation and differentiation into plasma cells. BCMA (B cell Maturation Antigen) is also expressed in B cell lymphoma and plasma cell neoplasms including myeloma. Because of this restricted expression, it has emerged as a potential therapeutic target. A number of clinical trials using either chimeric antigen receptor T cells or antibody drug conjugates targeting BCMA have been initiated to treat plasma cell myeloma and B cell lymphomas. Although the expression of BCMA has been investigated in experimental models and cell lines, no clinical grade assays that can assess BCMA expression in routine clinical specimens, in particular, in decalcified formalin fixed paraffin embedded (FFPE) bone marrow biopsies, with high specificity and sensitivity have been established. Screening patients who may be appropraite candidates for BCMA targeted therapy is therfore challenging. Given the new therapies targeting BCMA, we developed and validated a clinical grade assay to assess BCMA expression on B and plasma cell malignancies on routine FFPE specimen in clinical practice.Material and Methods: Total of 672 routine tissue and decalcified bone marrow biopsies were prospectively stained with anti-BCMA immunostain (Santa Cruz; Clone D6 Mouse Monoclonal Antibody) using standard methods. The cases included normal lymphoid tissues (n=45), B cell lymphoma (n=278), plasma cell neoplasms (multiple myeloma, n=162; plasmacytoma, n=13), other hematopoietic neoplasm and carcinomas (n=31 and 42, respectively). B cell lymphomas included low grade CLL/SLL, mantle cell lymphoma, marginal zone lymphoma and lymphoplasmacytic lymphoma and high grade lymphomas diffuse large B cell lymphoma (DLBCL), Burkitt and plasmablastic lymphoma. Sections from tonsils and reactive lymph nodes were used as a control. We developed a scoring system based on the predominant pattern (Golgi, membranous, Golgi and membranous), intensity (1+, 2+, 3+) and percentage (0-100%). We used >20% BCMA expression in the neoplastic cells as the positive cut off.Results: In normal lymphoid tissues, BCMA expression was restricted to plasma cells and germinal center B cells. BCMA expression was not detected in other tissues (epithelium, T cells, dendritic cells and histiocytes/macrophages). BCMA showed a high level of expression in B cell lineage malignancies and plasma cell neoplasms. 97.1% cases of plasma cell neoplasms were positive for BCMA with predominant Golgi and membranous pattern and strong (3+) intensity. B cell neoplasms (DLBCL and low grade B lymphomas) predominately showed membranous pattern with 2-3+ staining intensity. High grade lymphomas (Burkitt and plamablastic lymphoma) showed strong (3+) intensity with both membranous and Golgi pattern. In DLBCL, both ABC and GCB subtypes expressed BCMA but there was no significant difference in the intensity and pattern of staining (ABC type=39.1% vs. GCB type=35.1%). Among follicular lymphomas no significant difference was observed between grade 1-2 and grade 3. Eight cases (87.5%) of Burkitt lymphoma and seven cases (100%) of plasmablastic lymphoma showed strong and diffuse BCMA expression (3+ intensity; membranous and Golgi pattern). T cell lymphoma, Hodgkin lymphoma and myeloid and lymphoblastic lymphoma/leukemia were negative for BCMA immunostain. The results are summarized in Table 1 and Figure 1.Conclusion: This study shows broad expression of BCMA in a wide range of B and plasma cell neoplasms using a clinical grade assay, but not in normal tissues outside the lymphoid system or in other epithelial and hematopoietic neoplasms. BCMA expression is seen in many more B cell malignancies than previously recognized, including in a number of aggressive B cell neoplasms such as high grade B-cell lymphomas Burkitt and plasmablastic lymphomas. These findings suggest that the diseases that could be targeted by novel BCMA directed therapies are broader than previously realized. This assay will allow biomarker based selection of patients for BCMA targeted trials, and the semi-quantitative nature of the assay may allow the prediction of clinical outcomes for such therapies [Display omitted] DisclosuresSmith:Juno Therapeutics: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: BCMA targeted CAR T cells, Research Funding. Dogan:Peer Review Institute: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Roche Pharmaceuticals: Consultancy; Celgene: Consultancy.

Screening of anti-idiotypic domain antibody from phage library for development of Bt Cry1A simulants

Anti-idiotypic antibody technique is a new approach for the rapid development of insecticidal protein. In this study, anti-Cry1A polyclonal antibodies were used as antigen to screen the anti-idiotypic antibody that can simulate Cry1A toxins from a phage display human domain antibody (DAB) library. After four rounds of panning, five positive clones that have binding activities with anti-Cry1A polyclonal antibodies were obtained. Indirect competitive ELISA (IC-ELISA) results showed that the positive clone D6 showed significant inhibition for the binding of Cry1A toxins with anti-Cry1A polyclonal antibodies, and the inhibition ratio increased with the increase of D6 content. While, B3, F4, G5, C7 and the controls showed no obvious inhibition to Cry1A toxins. The results suggest that D6 is the “β” subtype anti-idiotypic antibody, which can simulate Cry1A toxins and competitive binding with anti-Cry1A polyclonal antibodies. Meanwhile, D6 had certain binding activity with the brush border membrane vesicles (BBMV) of p. xylostella, which was the receptor of Cry1A toxins. The results of bioassay showed that D6 had certain insecticidal activity, and the lethal concentration of 50% (LC50) was 976 ng/cm2. This study provides basic materials and experience for the development of Cry toxin simulants.

Optimum Combination of Alphamangostin-Dihydroartemisinin in Vitro as Antimalaria

Drug discovery effort need to be done because of the malaria drug resistance evidence. Against the available ACTs, this resistance also started to develop. Alphamangostin has antimalarial activity and has synergistic effect with dihydroartemisinin. The aim of this study was to look for the optimum ratio of this combination as antimalaria with the lowest IC50 (the most active) and the smallest Sum of FIC50 (the most synergistic effect). Three kinds of stock solution of combination of alphamangostin with dihydroartemisinin were made consisting of: 1) a half of IC50 alphamangostin with a half of dihydroartemisinin, 2) Three quarter of IC50 alphamangostin with a quarter of dihydroartemisinin, 3) a quarter of IC50 alphamangostin with three quarter of dihydroartemisinin. 3D7 clone of Plasmodium falciparum cultivation was treated by each of those stock solutions in various dilution duplicately. Parasitaemia percentage was counted and analyzed by probit analysis to find out the IC50 and the sum of FIC50 of those combinations. It was shown that IC50 and the sum of FIC50 of the first, second, and third combination was 0.0011 microgram/ mL and 0.733; 0.00023 microgram / mL and 0.115; 0.00028 microgram / mL and 0.233 consecutively. It seemed that the second combination was the most ideal combination according its synergistic effect.

Antiparasitic Activity of Bromotyrosine Alkaloids and New Analogues Isolated from the Fijian Marine Sponge Aplysinella rhax.

Ten bromotyrosine alkaloids were isolated and characterised from the marine sponge Aplysinella rhax (de Laubenfels 1954) collected from the Fiji Islands, which included one new bromotyrosine analogue, psammaplin P and two other analogues, psammaplin O and 3-bromo-2-hydroxy-5-(methoxycarbonyl)benzoic acid, which have not been previously reported from natural sources. HR-ESI-MS, 1D and 2D NMR spectroscopic methods were used in the elucidation of the compounds. Bisaprasin, a biphenylic dimer of psammaplin A, showed moderate activity with IC50 at 19±5 and 29±6 μM against Trypanzoma cruzi Tulahuen C4, and the lethal human malaria species Plasmodium falciparum clone 3D7, respectively, while psammaplins A and D exhibited low activity against both parasites. This is the first report of the antimalarial and antitrypanosomal activity of the psammaplin-type compounds. Additionally, the biosynthesis hypotheses of three natural products were proposed.

Human plasma plasminogen internalization route in Plasmodium falciparum-infected erythrocytes

BackgroundThe intra-erythrocytic development of the malaria parasite Plasmodium falciparum depends on the uptake of a number of essential nutrients from the host cell and blood plasma. It is widely recognized that the parasite imports low molecular weight solutes from the plasma and the consumption of these nutrients by P. falciparum has been extensively analysed. However, although it was already shown that the parasite also imports functional proteins from the vertebrate host, the internalization route through the different infected erythrocyte membranes has not yet been elucidated. In order to further understand the uptake mechanism, the study examined the trafficking of human plasminogen from the extracellular medium into P. falciparum-infected red blood cells.MethodsPlasmodium falciparum clone 3D7 was cultured in standard HEPES-buffered RPMI 1640 medium supplemented with 0.5% AlbuMAX. Exogenous human plasminogen was added to the P. falciparum culture and the uptake of this protein by the parasites was analysed by electron microscopy and Western blotting. Immunoprecipitation and mass spectrometry were performed to investigate possible protein interactions that may assist plasminogen import into infected erythrocytes. The effect of pharmacological inhibitors of different cellular physiological processes in plasminogen uptake was also tested.ResultsIt was observed that plasminogen was selectively internalized by P. falciparum-infected erythrocytes, with localization in plasma membrane erythrocyte and parasite’s cytosol. The protein was not detected in parasitic food vacuole and haemoglobin-containing vesicles. Furthermore, in erythrocyte cytoplasm, plasminogen was associated with the parasite-derived membranous structures tubovesicular network (TVN) and Maurer’s clefts. Several proteins were identified in immunoprecipitation assay and may be involved in the delivery of plasminogen across the P. falciparum multiple compartments.ConclusionThe findings here reported reveal new features regarding the acquisition of plasma proteins of the host by P. falciparum-infected erythrocytes, a mechanism that involves the exomembrane system, which is distinct from the haemoglobin uptake, clarifying a route that may be potentially targeted for inhibition studies.

PfSWIB, a potential chromatin regulator for var gene regulation and parasite development in Plasmodium falciparum

BackgroundVarious transcription factors are involved in the process of mutually exclusive expression and clonal variation of the Plasmodium multigene (var) family. Recent studies revealed that a P. falciparum SWI/SNF-related matrix-associated actin-dependent regulator of chromatin (PfSWIB) might trigger stage-specific programmed cell death (PCD), and was not only crucial for the survival and development of parasite, but also had profound effects on the parasite by interacting with other unknown proteins. However, it remains unclear whether PfSIWB is involved in transcriptional regulation of this virulence gene and its functional properties.MethodsA conditional knockdown system “PfSWIB-FKBP-LID” was introduced to the parasite clone 3D7, and an integrated parasite line “PfSWIB-HA-FKBP-LID” was obtained by drug cycling and clone screening. Growth curve analysis (GCA) was performed to investigate the growth and development of different parasite lines during 96 h in vitro culturing, by assessing parasitemia. Finally, we performed qPCR assays to detect var gene expression profiling in various comparison groups, as well as the mutually exclusive expression pattern of the var genes within a single 48 h life-cycle of P. falciparum in different parasite lines. In addition, RNA-seq was applied to analyze the var gene expression in different lines.ResultsGCA revealed that conditional knockdown of PfSWIB could interfere with the growth and development of P. falciparum. The parasitemia of PfSWIB∆ showed a significant decline at 96 h during in vitro culture compared with the PfSWIB and 3D7 lines (P < 0.0001). qPCR and RNA-seq analysis confirmed that depletion of PfSWIB not only silences upsA, upsC and partial upsB var genes, as well as removes the silencing of partial upsB var genes at the ring stage in PfSWIB∆ line, but also leads to aberrant expression of upsA and partial upsB/upsC var genes at the mature stage of P. falciparum, during a single 48-h life-cycle.ConclusionsWe demonstrated that PfSWIB was involved in the process of clonal variation in var gene expression, and crucial for the survival and development of Plasmodium parasite. These findings could provide better understanding of the mechanism and function of PfSWIB contributing to the pathogenesis in malaria parasites.

First Description of B Cell Maturation Antigen Expression in Light Chain Amyloidosis

Background B-cell maturation antigen (BCMA) is a transmembrane protein belonging to the tumor necrosis factor (TNF) superfamily involved in the regulation of B cell proliferation and survival as well as maturation/differentiation into plasma cells. In multiple myeloma cells, overexpression of BCMA has been shown to activate mitogen activated protein kinase pathways (AKT, ERK1/2, and NF-κB) and upregulates anti-apoptotic proteins (MCL1, BCL2, BCL-xL) resulting in cellular proliferation. Immunotherapeutic strategies targeting BCMA are showing great promise in heavily pre-treated refractory multiple myeloma. Light Chain Amyloidosis (AL) is a multisystem disorder of clonal plasma cells that results in the production of an abnormal light chain which misfolds and deposits in the organs leading to disruption of tissue architecture, cellular stress, dysfunction and eventually, death. The smaller burden and lower proliferative potential of the offending clonal plasma cells in amyloidosis may potentially lend itself favorably to immunotherapeutic strategies targeting BCMA. Given the efficacy of this approach in MM, the evaluation of BCMA expression on the surface of amyloidogenic plasma cells is warranted. Methods All patients diagnosed with Light chain Amyloidosis at Memorial Sloan Kettering Cancer Center, NY between January 1, 2012, and December 31, 2018, who had unstained bone marrow samples were identified. These unstained BM biopsy samples were prospectively stained for BCMA expression using Immunohistochemistry (IHC). We utilized a clinical-grade assay (clone D6; catalog sc-390147; company Santa-Cruz; monoclonal antibody; dilution 1:400) in a CLIA compliant setting. We scored the biopsies for BCMA expression, intensity, and site of staining. We also obtained their demographic details, staging, and cytogenetic information for the patients with available samples. Results During the queried period, 28 unstained samples were available for testing from the time of disease diagnosis. The median age of the population was 63 years (range 41-73). 64% of patients were male and consistent with the literature; a majority of patients (75%) had lambda-typic clonal plasma cells. Cytogenetic abnormalities using fluorescence in situ hybridization (FISH) were reviewed, t(11;14) was seen in 36% patients, and chromosome 1q and del 13q were each seen in 32% of patients. No patient had t(4;14) or del 17p. The median clonal PC burden in BM at diagnosis was 10% (range2-80%) and 36% had &gt; 10% plasma cells. In clonal PCs, the median BCMA expression was 80% (range 20-100%). Only one patient had a staining intensity under 50% (20%). Membranous staining was noted in 82% of patients and a Golgi pattern in 11%. The median staining intensity was 2 (range 1-3). Of the patients with baseline diagnostic samples available for testing, six patients had additional unstained bone marrow samples for staining at the time of relapse. The majority of patients (83%) who relapsed had &gt;10% plasma cells with a higher median plasma cell burden of 35% (range 10-80). The median BCMA expression was 65% (range 50-80) with no patient having &lt;50% expression. The staining pattern was membranous in 50%, Golgi in 17%, and Golgi-membranous in 33%. At the time of relapse, the median clonal PC burden was 13% (range 5-30). BCMA expression continued to be present at the time of relapse with a median 75% (range 50-100) with predominantly membranous staining (83%). The median staining intensity in both diagnostic and relapsed tissue within the six samples studied was 1. Conclusions Our study represents the first description of BCMA expression on the surface of amyloidogenic plasma cells to our knowledge. BCMA is uniformly expressed by pathologic PCs in AL amyloidosis both at the time of diagnosis and relapse. Given the efficacy of BCMA directed therapy in multiple myeloma, further investigation of these agents in light-chain amyloidosis are warranted and may provide an effective therapeutic strategy in this devastating disease. Figure Disclosures Dogan: Corvus Pharmaceuticals: Consultancy; Celgene: Consultancy; Seattle Genetics: Consultancy; Novartis: Consultancy; Takeda: Consultancy; Roche: Consultancy, Research Funding. Giralt:Takeda: Consultancy, Research Funding; Johnson &amp; Johnson: Consultancy, Research Funding; Kite: Consultancy; Novartis: Consultancy; Actinium: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy; Celgene: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Miltenyi: Research Funding; Spectrum Pharmaceuticals: Consultancy. Hassoun:Novartis: Consultancy; Janssen: Research Funding; Celgene: Research Funding. Landau:Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Research Funding; Prothena: Membership on an entity's Board of Directors or advisory committees; Caelum: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.

Aporphine alkaloids with in vitro antiplasmodial activity from the leaves of Phoebe tavoyana

One new aporphine named tavoyanine A (1), along with four known aporphines laetanine (2), roemerine (3), laurolitsine (4), and boldine (5), and one morphinandienone type sebiferine (6) were isolated from the leaves of Phoebe tavoyana (Meissn.) Hook f. (Lauraceae). The isolation was achieved by chromatographic techniques, and the structural elucidation was performed via spectral methods. This paper also reports the antiplasmodial activity of roemerine (3), laurolitsine (4), boldine (5), and sebiferine (6). The results showed that 3–6 have a potent inhibitory activity against the growth of Plasmodium falciparum 3D7 clone, with IC50 values of 0.89, 1.49, 1.65, and 2.76 µg/ml, respectively.

COMPARATIVE BIOLOGICAL EVALUATION OF SIX ENDOPHYTIC FUNGI ISOLATED FROM VINCA ROSEA LEAVES

In this study, a total of six endophytic fungi have been isolated from Vinca rosea (Apocynaceae) leaves growing in Egypt. The isolated fungi were identified morphologically and microscopically up to species to be; Alternaria phragmospora, Aspergillus awamori, Penicillium duclauxii, Penicillium melinii, Nigrospora sphaerica and Mucor ramosissimus. The extracts of the all identified fungi were screened biologically for antileukemic, cytotoxic, antimalarial, antileishmanial, antimicrobial, antioxidant and anti-inflammatory activities as well as for cannabinoid and opioid receptor binding affinities. Out of the six examined fungal extracts four exhibited promising antimalarial activities, four showed modeate antileukemic activities and two of them exhibited cytotoxic activities, three showed antioxidant activities, three exhibited anti-inflammatory activities, and the only one showed an antifungal activity. Alternaria phragmospora was the most active antimalarial agent inhibiting Plasmodium falciparum D6 and W2 clones with IC50 values of 1.9 and 2.1 μg/mL, respectively. Alternaria phragmospora extractwas subjected to liquid-liquid partition using 90% MeOH, hexane then BuOH and H2O. MeOH and BuOH fractions exhibited strong activities against Plasmodium falciparum D6 clone with IC50 values of 1.3 and 28 μg/mL and W2 clone with IC50 values of 1.4 and 28 μg/mL, respectively. These results may be an excellent opportunity to get a new antimalarial drug derived from endophytic fungi.

Transient temperature fluctuations severely decrease P. falciparum susceptibility to artemisinin in vitro

Clinical studies suggest that outcomes for hospitalised malaria patients can be improved by managed hypothermia during treatment. We examined the impact of short pulses of low temperature on ring-stage susceptibility of Plasmodium falciparum to artemisinin in vitro. The usually artemisinin-sensitive clone 3D7 exhibited substantially reduced ring-stage susceptibility to a 4-h pulse of 700 nM dihydro-artemisinin administered during a 5-h pulse of low temperature down to 17 °C. Parasite growth through the subsequent asexual cycle was not affected by the temperature pulse. Chloroquine and pyronaridine susceptibility, in a standard 48-h test, was not affected by brief exposures to low temperature. Fever-like temperature pulses up to 40 °C were also accompanied by enhanced ring-stage survival of 700 nM artemisinin pulses, but parasite growth was generally attenuated at this temperature. We discuss these findings in relation to the possible activation of parasite stress responses, including the unfolded protein response, by hypo- or hyper-thermic conditions. Physiological states may need to be considered in artemisinin-treated P. falciparum patients.

English

Multidrug resistance Plasmodium falciparum remains a significant global health problem worldwide. New alternative antimalarial drugs are urgently needed. Dioscorea membranacea Pierre. is a Thai-medicinal plant that has been shown to exhibit a wide range of pharmacological activities. The study aimed to investigate antimalarial activity and possible protein targets of action of the crude ethanolic extract of the rhizome of this plant. The in vitro antimalarial activity expressed as IC50 (concentration that inhibits the parasite growth by 50%) of the extract against 3D7 chloroquine-sensitive P. falciparum and K1 chloroquine-resistant P. falciparum clones were 10.1 (8.8-10.3) and 9.3 (9.17-9.63) µg/ml [median (range)], respectively. The cytotoxicity of against the human fibroblast cell OUMS-36T-1F was 96.4 (96.3-96.5) µg/ml. The selectivity index (SI) for the 3D7 and K1 clones was 9.5 and 10.4, respectively. Preliminary investigation of the protein targets of action in 3D7 P. falciparum clone revealed 13 up-regulated protein spots and 14 down-regulated protein spots. For further development of D. membranacea Pierre. as a promising antimalarial drug candidate, identification of these proteins by mass spectrometry and investigation of their mode of antimalarial actions are encouraged. Key words: Malaria, proteomics, Dioscorea membranacea Pierre.

Production, characterization, and epitope mapping of a monoclonal antibody against genotype VII Newcastle disease virus V protein

Newcastle disease virus (NDV) V protein is crucial for viral interferon (IFN) antagonism and virulence, determining its host range restriction. However, little information is available on the B cell epitopes of V protein and the subcellular movement of V protein in the process of NDV infection. In this study, the monoclonal antibody (mAb) clone 3D7 against genotype VII NDV V protein was generated by immunizing mice with a purified recombinant His-tagged carboxyl-terminal domain (CTD) region of V protein. Fine epitope mapping analysis and B-cell epitope prediction indicated that mAb 3D7 recognized a linear epitope 152RGPAELWK159, which is located in the V protein CTD region. Sequence alignment showed that the mAb clone 3D7-recognized epitope is highly conserved among Class II genotype VII NDV strains, but not among other genotypes, suggesting it could serve as a genetic marker to differentiate NDV genotypes. Furthermore, the movement of V protein during NDV replication in infected cells were determined by using this mAb. It was found that V protein localized around the nucleus during virus replication. The establishment of V protein-specific mAb and identification of its epitope extend our understanding of the antigenic characteristics of V protein and provide a basis for the development of epitope-based diagnostic assays.