ABSTRACT
Low vaginal self-sampling has been pioneered as an important development to improve uptake of cervical screening globally. Limited research is available in specific patient groups in the UK exploring views around self-sampling to detect high-risk human papillomavirus (hrHPV) DNA. Therefore, we explored patient views to support development of a novel point-of-care self-sampling cervical cancer screening device, by undertaking a cross-sectional semi-structured questionnaire survey to explore preferences, acceptability, barriers and facilitators around self-sampling. Patients attending a colposcopy clinic, 25-64 years old, were invited to participate after having carried out a low vaginal self-sample using a regular flocked swab. Participants self-completed an anonymous 12-point questionnaire. Quantitative data were analysed in MS Excel and Graphpad Prism, and qualitative data with Nvivo. We recruited 274 patients with a questionnaire response rate of 76%. Acceptability of self-sampling was high (95%, n = 187/197; Cronbachs-α = 0.778). Participants were asked their choice of future screening method: a) low vaginal self-sampling, b) healthcare professional collected vaginal swab, c) cervical brush sample with healthcare professional speculum examination, or d) no preference. Preferences were: a) 37% (n = 74/198), b) 19% (n = 37/198); c) 9% (n = 17/198), and d) 35% (n = 70/198), showing no single option as a strong preference. Key motivators were: Test simplicity (90%, n = 170/190), speed (81%, n = 153/190) and less pain (65%, n = 123/190). Barriers included lack of confidence taking the sample (53%, n = 10/19), resulting in preference for a healthcare professional sample (47%, n = 9/19). Whilst self-sampling showed high acceptability, lack of strong preference for screening method may reflect that respondents attending colposcopy are already engaged with screening and have differing perception of cervical cancer risk. This group appear less likely to 'switch' to self-sampling, and it may be better targeted within primary and community care, focusing on under-screened populations. Any shift in this paradigm in the UK requires comprehensive education and support for patients and providers.
ABSTRACT
INTRODUCTION: The coronavirus disease 2019 (COVID-19) pandemic resulted in a race to develop effective treatments largely through drug repurposing via adaptive platform trials on a global scale. Drug repurposing trials have focused on potential antiviral therapies aimed at preventing viral replication, anti-inflammatory agents, antithrombotic agents and immune modulators through a number of adaptive platform trials. Living systematic reviews have also enabled evidence synthesis and network meta-analysis as clinical trial data emerge globally. SOURCES OF DATA: Recent published literature. AREAS OF AGREEMENT: Corticosteroids and immunomodulators that antagonize the interleukin-6 (IL-6) receptor have been shown to play a critical role in modulating inflammation and improving clinical outcomes in hospitalized patients. Inhaled budesonide reduces the time to recovery in older patients with mild-to-moderate COVID-19 managed in the community. AREAS OF CONTROVERSY: The clinical benefit of remdesivir remains controversial with conflicting evidence from different trials. Remdesivir led to a reduction in time to clinical recovery in the ACTT-1 trial. However, the World Health Organization SOLIDARITY and DISCOVERY trial did not find a significant benefit on 28-day mortality and clinical recovery. GROWING POINTS: Other treatments currently being investigated include antidiabetic drug empagliflozin, antimalarial drug artesunate, tyrosine kinase inhibitor imatinib, immunomodulatory drug infliximab, antiviral drug favipiravir, antiparasitic drug ivermectin and antidepressant drug fluvoxamine. AREAS TIMELY FOR DEVELOPING RESEARCH: The timing of therapeutic interventions based on postulated mechanisms of action and the selection of clinically meaningful primary end points remain important considerations in the design and implementation of COVID-19 therapeutic trials.
Subject(s)
COVID-19 , Aged , Humans , Adrenal Cortex Hormones , Antiviral Agents/therapeutic use , Drug Repositioning , Imatinib Mesylate , Randomized Controlled Trials as Topic , Systematic Reviews as TopicABSTRACT
Accurate and rapid point-of-care (PoC) diagnostics are critical to the control of the COVID-19 pandemic. The current standard for accurate diagnosis of SARS-CoV-2 is laboratory-based reverse transcription polymerase chain reaction (RT-PCR) assays. Here, a preliminary prospective performance evaluation of the QuantuMDx Q-POC SARS-CoV-2 RT-PCR assay is reported. Between November 2020 and March 2021, 49 longitudinal combined nose/throat (NT) swabs from 29 individuals hospitalised with RT-PCR confirmed COVID-19 were obtained at St George's Hospital, London. In addition, 101 mid-nasal (MN) swabs were obtained from healthy volunteers in June 2021. These samples were used to evaluate the Q-POC SARS-CoV-2 RT-PCR assay. The primary analysis was to compare the sensitivity and specificity of the Q-POC test against a reference laboratory-based RT-PCR assay. The overall sensitivity of the Q-POC test compared with the reference test was 96.88% (83.78- 99.92% CI) for a cycle threshold (Ct) cut-off value for the reference test of 35 and 80.00% (64.35-90.95% CI) without altering the reference test's Ct cut-off value of 40. The Q-POC test is a sensitive, specific and rapid PoC test for SARS-CoV-2 at a reference Ct cut-off value of 35. The Q-POC test provides an accurate option for RT-PCR at PoC without the need for sample pre-processing and laboratory handling, enabling rapid diagnosis and clinical triage in acute care and other settings.
Subject(s)
COVID-19 , Humans , COVID-19/diagnosis , SARS-CoV-2/genetics , Reverse Transcriptase Polymerase Chain Reaction , Point-of-Care Systems , Pandemics , Prospective Studies , COVID-19 Testing , Clinical Laboratory Techniques , Sensitivity and SpecificityABSTRACT
INTRODUCTION: Patients with gastrointestinal (GI) cancers have an increased risk of serious complications and death from SARS-CoV-2 infection. The immunogenicity of vaccines in patients with GI cancers receiving anti-cancer therapies is unclear. We conducted a prospective study to evaluate the prevalence of neutralizing antibodies in a cohort of GI cancer patients receiving chemotherapy following SARS-CoV-2 vaccination. MATERIALS AND METHODS: Between September 2020 and April 2021, patients with cancer undergoing chemotherapy were enrolled. At baseline (day 0), days 28, 56, and 84, we assessed serum antibodies to SARS-CoV-2 spike (anti-S) and anti-nucleocapsid (anti-NP) and concomitantly assessed virus neutralization using a pseudovirus neutralization assay. Patients received either the Pfizer/BioNTech BNT162b2, or the Oxford/AstraZeneca ChAdOx1 vaccine. RESULTS: All 152 patients enrolled had a prior diagnosis of cancer; colorectal (n = 80, 52.6%), oesophagogastric (n = 38, 25.0%), and hepato pancreatic biliary (n = 22, 12.5%). Nearly all were receiving systemic anti-cancer therapy (99.3%). Of the 51 patients who did not receive a vaccination prior to, or during the study, 5 patients had detectable anti-NP antibodies. Ninety-nine patients received at least one dose of vaccine prior to, or during the study. Within 19 days following the first dose of vaccine, 30.0% had anti-S detected in serum which increased to 70.2% at days 20-39. In the 19 days following a second dose, anti-S positivity was 84.2% (32/38). However, pseudovirus neutralization titers (pVNT80) decreased from days 20 to 39. CONCLUSION: Despite the immunosuppressive effects of chemotherapy, 2 doses of SARS-CoV-2 vaccines are able to elicit a protective immune response in patients' ongoing treatment for gastrointestinal cancers. Decreases in pseudoviral neutralization were observed after 20-39 days, re-affirming the current recommendation for vaccine booster doses. CLINICAL TRIAL REGISTRATION NUMBER: NCT04427280.
Subject(s)
COVID-19 Vaccines , COVID-19 , Gastrointestinal Neoplasms , Immunogenicity, Vaccine , Humans , Antibodies , BNT162 Vaccine , Gastrointestinal Neoplasms/drug therapy , Prospective Studies , SARS-CoV-2ABSTRACT
Treatment failures with artemisinin combination therapies (ACTs) threaten global efforts to eradicate malaria. They highlight the importance of identifying drug targets and new inhibitors and of studying how existing antimalarial classes work. Here, we report the successful development of a heterologous expression-based compound-screening tool. The validated drug target Plasmodium falciparum ATPase 6 (PfATP6) and a mammalian orthologue (sarco/endoplasmic reticulum calcium ATPase 1a [SERCA1a]) were functionally expressed in Saccharomyces cerevisiae, providing a robust, sensitive, and specific screening tool. Whole-cell and in vitro assays consistently demonstrated inhibition and labeling of PfATP6 by artemisinins. Mutations in PfATP6 resulted in fitness costs that were ameliorated in the presence of artemisinin derivatives when studied in the yeast model. As previously hypothesized, PfATP6 is a target of artemisinins. Mammalian SERCA1a can be mutated to become more susceptible to artemisinins. The inexpensive, low-technology yeast screening platform has identified unrelated classes of druggable PfATP6 inhibitors. Resistance to artemisinins may depend on mechanisms that can concomitantly address multitargeting by artemisinins and fitness costs of mutations that reduce artemisinin susceptibility.
Subject(s)
Antimalarials , Artemisinins , Malaria, Falciparum , Animals , Antimalarials/pharmacology , Antimalarials/therapeutic use , Artemisinins/pharmacology , Artemisinins/therapeutic use , Calcium-Transporting ATPases/genetics , Calcium-Transporting ATPases/metabolism , Calcium-Transporting ATPases/therapeutic use , Drug Resistance , Malaria, Falciparum/drug therapy , Mammals , Plasmodium falciparum/genetics , Plasmodium falciparum/metabolism , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolismABSTRACT
Severe acute respiratory coronavirus 2 (SARS-CoV-2) has spread globally since its emergence in 2019. Most SARS-CoV-2 infections generate immune responses leading to rising levels of immunoglobulins (Ig) M, A and G which can be detected using diagnostic tests including enzyme-linked immunosorbent assays (ELISA). Whilst implying previous SARS-CoV-2 infection, the detection of Ig by ELISA does not guarantee the presence of neutralising antibodies (NAb) that can prevent the virus infecting cells. Plaque reduction neutralisation tests (PRNT) detect NAb, but are not amenable to mass testing as they take several days and require use of SARS-CoV-2 in high biocontainment laboratories. We evaluated the ability of IgG and IgM ELISAs targeting SARS-CoV-2 spike subunit 1 receptor binding domain (S1-RBD), and spike subunit 2 (S2) and nucleocapsid protein (NP), at predicting the presence and magnitude of NAb determined by PRNT. IgG S2 + NP ELISA was 96.8% [95% CI 83.8-99.9] sensitive and 88.9% [95% CI 51.8-99.7] specific at predicting the presence of NAbs (PRNT80 > 1:40). IgG and IgM S1-RBD ELISAs correlated with PRNT titre, with higher ELISA results increasing the likelihood of a robust neutralising response. The IgM S1-RBD assay can be used as a rapid, high throughput test to approximate the magnitude of NAb titre.
Subject(s)
Antibodies, Viral/immunology , COVID-19/immunology , Immunoglobulin G/immunology , Immunoglobulin M/immunology , Neutralization Tests , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Aged , Enzyme-Linked Immunosorbent Assay , Female , Humans , Male , Middle AgedABSTRACT
BACKGROUND: Individuals infected with SARS-CoV-2 develop neutralising antibodies. We investigated the proportion of individuals with SARS-CoV-2 neutralising antibodies after infection and how this proportion varies with selected covariates. METHODOLOGY/PRINCIPAL FINDINGS: This systematic review and meta-analysis examined the proportion of individuals with SARS-CoV-2 neutralising antibodies after infection and how these proportions vary with selected covariates. Three models using the maximum likelihood method assessed these proportions by study group, covariates and individually extracted data (protocol CRD42020208913). A total of 983 reports were identified and 27 were included. The pooled (95%CI) proportion of individuals with neutralising antibodies was 85.3% (83.5-86.9) using the titre cut off >1:20 and 83.9% (82.2-85.6), 70.2% (68.1-72.5) and 54.2% (52.0-56.5) with titres >1:40, >1:80 and >1:160, respectively. These proportions were higher among patients with severe COVID-19 (e.g., titres >1:80, 84.8% [80.0-89.2], >1:160, 74.4% [67.5-79.7]) than those with mild presentation (56.7% [49.9-62.9] and 44.1% [37.3-50.6], respectively) and lowest among asymptomatic infections (28.6% [17.9-39.2] and 10.0% [3.7-20.1], respectively). IgG and neutralising antibody levels correlated poorly. CONCLUSIONS/SIGNIFICANCE: 85% of individuals with proven SARS-CoV-2 infection had detectable neutralising antibodies. This proportion varied with disease severity, study setting, time since infection and the method used to measure antibodies.
Subject(s)
Antibodies, Neutralizing/blood , Antibodies, Viral/blood , COVID-19/immunology , SARS-CoV-2/immunology , Acute Disease , COVID-19/epidemiology , Convalescence , Humans , PrevalenceABSTRACT
Serological testing is emerging as a powerful tool to progress our understanding of COVID-19 exposure, transmission and immune response. Large-scale testing is limited by the need for in-person blood collection by staff trained in venepuncture, and the limited sensitivity of lateral flow tests. Capillary blood self-sampling and postage to laboratories for analysis could provide a reliable alternative. Two-hundred and nine matched venous and capillary blood samples were obtained from thirty nine participants and analysed using a COVID-19 IgG ELISA to detect antibodies against SARS-CoV-2. Thirty eight out of thirty nine participants were able to self-collect an adequate sample of capillary blood (≥ 50 µl). Using plasma from venous blood collected in lithium heparin as the reference standard, matched capillary blood samples, collected in lithium heparin-treated tubes and on filter paper as dried blood spots, achieved a Cohen's kappa coefficient of > 0.88 (near-perfect agreement, 95% CI 0.738-1.000). Storage of capillary blood at room temperature for up to 7 days post sampling did not affect concordance. Our results indicate that capillary blood self-sampling is a reliable and feasible alternative to venepuncture for serological assessment in COVID-19.
Subject(s)
Blood Specimen Collection/methods , COVID-19 Serological Testing/methods , COVID-19/diagnosis , SARS-CoV-2/isolation & purification , Adult , COVID-19/blood , Dried Blood Spot Testing/methods , Enzyme-Linked Immunosorbent Assay/methods , Female , Humans , Male , Middle Aged , Young AdultABSTRACT
Artemisinin-based combination therapies (ACTs) have demonstrated in vitro inhibition of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Artemisinins have also shown anti-inflammatory effects, including inhibition of interleukin-6 (IL-6) that plays a key role in the development of severe coronavirus disease 2019 (COVID-19). There is now sufficient evidence for the effectiveness of ACTs, and in particular artesunate/pyronaridine, to support clinical studies for COVID-19 infections.
Subject(s)
Antimalarials/therapeutic use , COVID-19 Drug Treatment , Drug Repositioning , Antiviral Agents/therapeutic use , Artemisinins/pharmacology , Artesunate/therapeutic use , Cytokine Release Syndrome/drug therapy , Drug Combinations , Humans , Naphthyridines/therapeutic use , SARS-CoV-2/drug effectsABSTRACT
We investigated the dynamics of seroconversion in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. During March 29-May 22, 2020, we collected serum samples and associated clinical data from 177 persons in London, UK, who had SARS-CoV-2 infection. We measured IgG against SARS-CoV-2 and compared antibody levels with patient outcomes, demographic information, and laboratory characteristics. We found that 2.0%-8.5% of persons did not seroconvert 3-6 weeks after infection. Persons who seroconverted were older, were more likely to have concurrent conditions, and had higher levels of inflammatory markers. Non-White persons had higher antibody concentrations than those who identified as White; these concentrations did not decline during follow-up. Serologic assay results correlated with disease outcome, race, and other risk factors for severe SARS-CoV-2 infection. Serologic assays can be used in surveillance to clarify the duration and protective nature of humoral responses to SARS-CoV-2 infection.
Subject(s)
COVID-19/blood , COVID-19/immunology , Immunoglobulin G/blood , SARS-CoV-2 , Seroconversion , Adult , Aged , Antibodies, Viral/blood , COVID-19/physiopathology , Enzyme-Linked Immunosorbent Assay , Female , Humans , Male , Middle Aged , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
Artemisinins are a unique class of antimalarial drugs with significant potential for drug repurposing for a wide range of diseases including cancer. Cancer is a leading cause of death globally and the majority of cancer related deaths occur in Low and Middle Income Countries (LMICs) where conventional treatment options are often limited by financial cost. Drug repurposing can significantly shorten new therapeutic discovery pathways, ensuring greater accessibility and affordability globally. Artemisinins have an excellent safety and tolerability profile as well as being affordable for deployment in Low and Middle Class Income Countries at around USD1 per daily dose. Robust, well designed clinical trials of artemisinin drug repurposing are indicated for a variety of different cancers and treatment settings.
Subject(s)
Antimalarials/therapeutic use , Antineoplastic Agents, Phytogenic/therapeutic use , Artemisinins/therapeutic use , Drug Repositioning , Neoplasms/drug therapy , Animals , Antimalarials/adverse effects , Antineoplastic Agents, Phytogenic/adverse effects , Artemisinins/adverse effects , Humans , Neoplasms/epidemiology , Neoplasms/metabolism , Neoplasms/pathology , Signal Transduction , Translational Research, BiomedicalABSTRACT
The aim of this study was to assess pathogen DNA extraction with a new spin column-based method (DNA-XT). DNA from either whole-blood samples spiked with Plasmodium falciparum or Leishmania donovani amastigote culture was extracted with DNA-XT and compared with that produced by a commercial extraction kit (DNeasy®). Eluates from large and small sample volumes were assessed by PCR and spectroscopy. Using a small volume (5 µl) of blood, the DNA-XT and DNeasy methods produced eluates with similar DNA concentrations (0.63 vs 1.06 ng/µl, respectively). The DNA-XT method produced DNA with lower PCR inhibition than DNeasy. The new technique was also twice as fast and required fewer plastics and manipulations but had reduced total recovered DNA compared with DNeasy.
Subject(s)
DNA, Protozoan/blood , Leishmania donovani/isolation & purification , Plasmodium falciparum/isolation & purification , DNA, Protozoan/isolation & purification , Genome, Protozoan , HumansABSTRACT
Toxoplasma gondii parasites rapidly exit their host cell when exposed to calcium ionophores. Calcium-dependent protein kinase 3 (TgCDPK3) was previously identified as a key mediator in this process, as TgCDPK3 knockout (∆cdpk3) parasites fail to egress in a timely manner. Phosphoproteomic analysis comparing WT with ∆cdpk3 parasites revealed changes in the TgCDPK3-dependent phosphoproteome that included proteins important for regulating motility, but also metabolic enzymes, indicating that TgCDPK3 controls processes beyond egress. Here we have investigated a predicted direct target of TgCDPK3, ApiAT5-3, a putative transporter of the major facilitator superfamily, and show that it is rapidly phosphorylated at serine 56 after induction of calcium signalling. Conditional knockout of apiAT5-3 results in transcriptional upregulation of most ribosomal subunits, but no alternative transporters, and subsequent parasite death. Mutating the S56 to a non-phosphorylatable alanine leads to a fitness cost, suggesting that phosphorylation of this residue is beneficial, albeit not essential, for tyrosine import. Using a combination of metabolomics and heterologous expression, we confirmed a primary role in tyrosine import for ApiAT5-3. However, no significant differences in tyrosine import could be detected in phosphorylation site mutants showing that if tyrosine transport is affected by S56 phosphorylation, its regulatory role is subtle.
Subject(s)
Protein Kinases/metabolism , Protozoan Proteins/metabolism , Toxoplasma/genetics , Toxoplasma/metabolism , Calcium Signaling , Calcium-Binding Proteins/metabolism , Gene Expression Regulation , Gene Knockout Techniques , Metabolomics , Mutation , Phosphorylation , Protein Kinases/genetics , Protozoan Proteins/genetics , Tyrosine/metabolismABSTRACT
Nucleic acid testing (NAT) for pathogenic filoviruses plays a key role in surveillance and to control the spread of infection. As they share clinical features with other pathogens, the initial spread of these viruses can be misdiagnosed. Tests that can identify a pathogen in the initial stages of infection are essential to control outbreaks. Since the Ebola virus disease (EVD) outbreak in 2014-2016 several tests have been developed that are faster than previous tests and more suited for field use. Furthermore, the ability to test for a range of pathogens simultaneously has been expanded to improve clinical pathway management of febrile syndromes. This review provides an overview of these novel diagnostic tests.
Subject(s)
Filoviridae Infections/diagnosis , Filoviridae/isolation & purification , Molecular Diagnostic Techniques/methods , RNA, Viral/isolation & purification , Humans , RNA, Viral/geneticsABSTRACT
Background: Atovaquone/proguanil, registered as Malarone®, is a fixed-dose combination recommended for first-line treatment of uncomplicated Plasmodium falciparum malaria in non-endemic countries and its prevention in travellers. Mutations in the cytochrome bc1 complex are causally associated with atovaquone resistance. Methods: This systematic review assesses the clinical efficacy of atovaquone/proguanil treatment of uncomplicated malaria and examines the extent to which codon 268 mutation in cytochrome b influences treatment failure and recrudescence based on published information. Results: Data suggest that atovaquone/proguanil treatment efficacy is 89%-98% for P. falciparum malaria (from 27 studies including between 18 and 253 patients in each case) and 20%-26% for Plasmodium vivax malaria (from 1 study including 25 patients). The in vitro P. falciparum phenotype of atovaquone resistance is an IC50 value >28 nM. Case report analyses predict that recrudescence in a patient presenting with parasites carrying cytochrome b codon 268 mutation will occur on average at day 29 (95% CI: 22, 35), 19 (95% CI: 7, 30) days longer than if the mutation is absent. Conclusions: Evidence suggests atovaquone/proguanil treatment for P. falciparum malaria is effective. Late treatment failure is likely to be associated with a codon 268 mutation in cytochrome b, though recent evidence from animal models suggests these mutations may not spread within the population. However, early treatment failure is likely to arise through alternative mechanisms, requiring further investigation.
Subject(s)
Atovaquone/pharmacology , Drug Resistance, Multiple/genetics , Malaria, Falciparum/drug therapy , Malaria, Vivax/drug therapy , Plasmodium falciparum/drug effects , Proguanil/pharmacology , Treatment Failure , Drug Combinations , Drug Therapy, Combination , Electron Transport Complex III/genetics , Humans , Malaria, Falciparum/prevention & control , Malaria, Vivax/prevention & control , Mutation , TravelABSTRACT
BACKGROUND: The rVSVΔG-ZEBOV-GP vaccine prevented Ebola virus disease when used at 2 × 107 plaque-forming units (PFU) in a trial in Guinea. This study provides further safety and immunogenicity data. METHODS AND FINDINGS: A randomised, open-label phase I trial in Lambaréné, Gabon, studied 5 single intramuscular vaccine doses of 3 × 103, 3 × 104, 3 × 105, 3 × 106, or 2 × 107 PFU in 115 adults and a dose of 2 × 107 PFU in 20 adolescents and 20 children. The primary objective was safety and tolerability 28 days post-injection. Immunogenicity, viraemia, and shedding post-vaccination were evaluated as secondary objectives. In adults, mild-to-moderate adverse events were frequent, but there were no serious or severe adverse events related to vaccination. Before vaccination, Zaire Ebola virus (ZEBOV)-glycoprotein (GP)-specific and ZEBOV antibodies were detected in 11% and 27% of adults, respectively. In adults, 74%-100% of individuals who received a dose 3 × 104, 3 × 105, 3 × 106, or 2 × 107 PFU had a ≥4.0-fold increase in geometric mean titres (GMTs) of ZEBOV-GP-specific antibodies at day 28, reaching GMTs of 489 (95% CI: 264-908), 556 (95% CI: 280-1,101), 1,245 (95% CI: 899-1,724), and 1,503 (95% CI: 931-2,426), respectively. Twenty-two percent of adults had a ≥4-fold increase of ZEBOV antibodies, with GMTs at day 28 of 1,015 (647-1,591), 1,887 (1,154-3,085), 1,445 (1,013-2,062), and 3,958 (2,249-6,967) for the same doses, respectively. These antibodies persisted up to day 180 for doses ≥3 × 105 PFU. Adults with antibodies before vaccination had higher GMTs throughout. Neutralising antibodies were detected in more than 50% of participants at doses ≥3 × 105 PFU. As in adults, no serious or severe adverse events related to vaccine occurred in adolescents or children. At day 2, vaccine RNA titres were higher for adolescents and children than adults. At day 7, 78% of adolescents and 35% of children had recombinant vesicular stomatitis virus RNA detectable in saliva. The vaccine induced high GMTs of ZEBOV-GP-specific antibodies at day 28 in adolescents, 1,428 (95% CI: 1,025-1,989), and children, 1,620 (95% CI: 806-3,259), and in both groups antibody titres increased up to day 180. The absence of a control group, lack of stratification for baseline antibody status, and imbalances in male/female ratio are the main limitations of this study. CONCLUSIONS: Our data confirm the acceptable safety and immunogenicity profile of the 2 × 107 PFU dose in adults and support consideration of lower doses for paediatric populations and those who request boosting. TRIAL REGISTRATION: Pan African Clinical Trials Registry PACTR201411000919191.
Subject(s)
Adaptive Immunity/drug effects , Ebola Vaccines/administration & dosage , Ebolavirus/immunology , Hemorrhagic Fever, Ebola/prevention & control , Immunogenicity, Vaccine , Adolescent , Adult , Age Factors , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , Biomarkers/blood , Child , Ebola Vaccines/adverse effects , Ebola Vaccines/immunology , Female , Gabon , Hemorrhagic Fever, Ebola/diagnosis , Hemorrhagic Fever, Ebola/immunology , Hemorrhagic Fever, Ebola/virology , Humans , Injections, Intramuscular , Male , Middle Aged , Time Factors , Treatment Outcome , Vaccination , Virus Shedding , Young AdultABSTRACT
Prior to infecting erythrocytes and causing malaria symptoms, Plasmodium parasites undergo an obligatory phase of invasion and extensive replication inside their mammalian host's liver cells that depends on the parasite's ability to obtain the nutrients it requires for its intra-hepatic growth and multiplication. Here, we show that L-arginine (Arg) uptake through the host cell's SLC7A2-encoded transporters is essential for the parasite's development and maturation in the liver. Our data suggest that the Arg that is taken up is primarily metabolized by the arginase pathway to produce the polyamines required for Plasmodium growth. Although the parasite may hijack the host's biosynthesis pathway, it relies mainly upon its own arginase-AdoMetDC/ODC pathway to acquire the polyamines it needs to develop. These results identify for the first time a pivotal role for Arg-dependent polyamine production during Plasmodium's hepatic development and pave the way to the exploitation of strategies to impact liver infection by the malaria parasite through the modulation of Arg uptake and polyamine synthesis.
Subject(s)
Arginine/metabolism , Liver/metabolism , Liver/parasitology , Malaria/metabolism , Malaria/parasitology , Plasmodium , Animals , Cationic Amino Acid Transporter 2/genetics , Cationic Amino Acid Transporter 2/metabolism , Cell Line , Disease Models, Animal , Gene Expression Regulation , Hepatocytes/metabolism , Hepatocytes/parasitology , Host-Pathogen Interactions , Humans , Malaria/genetics , Mice , Mice, Knockout , Plasmodium bergheiABSTRACT
Intracellular pathogens have evolved mechanisms to ensure their survival and development inside their host cells. Here, we show that glucose is a pivotal modulator of hepatic infection by the rodent malaria parasite Plasmodium berghei and that glucose uptake via the GLUT1 transporter is specifically enhanced in P. berghei-infected cells. We further show that ATP levels of cells containing developing parasites are decreased, which is known to enhance membrane GLUT1 activity. In addition, GLUT1 molecules are translocated to the membrane of the hepatic cell, increasing glucose uptake at later stages of infection. Chemical inhibition of GLUT1 activity leads to a decrease in glucose uptake and the consequent impairment of hepatic infection, both in vitro and in vivo. Our results reveal that changes in GLUT1 conformation and cellular localization seem to be part of an adaptive host response to maintain adequate cellular nutrition and energy levels, ensuring host cell survival and supporting P. berghei hepatic development.
Subject(s)
Glucose Transporter Type 1/metabolism , Glucose/metabolism , Host-Pathogen Interactions , Liver/pathology , Liver/parasitology , Malaria/pathology , Plasmodium berghei/physiology , Adenosine Triphosphate/analysis , Animals , Cell Line , Cytosol/chemistry , Humans , Immunohistochemistry , Mice, Inbred C57BL , Plasmodium berghei/growth & developmentABSTRACT
Apicomplexa are a large group of eukaryotic, single-celled parasites, with complex life cycles that occur within a wide range of different microenvironments. They include important human pathogens such as Plasmodium, the causal agent of malaria, and Toxoplasma, which causes toxoplasmosis most often in immunocompromised individuals. Despite environmental differences in their life cycles, these parasites retain the ability to obtain nutrients, remove waste products, and control ion balances. They achieve this flexibility by relying on proteins that can deliver and remove solutes. This reliance on transport proteins for essential functions makes these pathways excellent potential targets for drug development programmes. Transport proteins are frequently key mediators of drug resistance by their ability to remove drugs from their sites of action. The study of transport processes mediated by integral membrane proteins and, in particular, identification of their physiological functions and localisation, and differentiation from host orthologues has already established new validated drug targets. Our understanding of how apicomplexan parasites have adapted to changing environmental challenges has also increased through the study of their transporters. This brief introduction to membrane transporters of apicomplexans highlights recent discoveries focusing on Plasmodium and emphasises future directions.