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1.
Microb Genom ; 5(9)2019 09.
Article in English | MEDLINE | ID: mdl-31526447

ABSTRACT

Among long-stay critically ill patients in the adult intensive care unit (ICU), there are often marked changes in the complexity of the gut microbiota. However, it remains unclear whether such patients might benefit from enhanced surveillance or from interventions targeting the gut microbiota or the pathogens therein. We therefore undertook a prospective observational study of 24 ICU patients, in which serial faecal samples were subjected to shotgun metagenomic sequencing, phylogenetic profiling and microbial genome analyses. Two-thirds of the patients experienced a marked drop in gut microbial diversity (to an inverse Simpson's index of <4) at some stage during their stay in the ICU, often accompanied by the absence or loss of potentially beneficial bacteria. Intravenous administration of the broad-spectrum antimicrobial agent meropenem was significantly associated with loss of gut microbial diversity, but the administration of other antibiotics, including piperacillin/tazobactam, failed to trigger statistically detectable changes in microbial diversity. In three-quarters of ICU patients, we documented episodes of gut domination by pathogenic strains, with evidence of cryptic nosocomial transmission of Enterococcus faecium. In some patients, we also saw an increase in the relative abundance of apparent commensal organisms in the gut microbiome, including the archaeal species Methanobrevibacter smithii. In conclusion, we have documented a dramatic absence of microbial diversity and pathogen domination of the gut microbiota in a high proportion of critically ill patients using shotgun metagenomics.


Subject(s)
Biodiversity , Gastrointestinal Microbiome , Adult , Aged , Aged, 80 and over , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Critical Illness , Enterococcus faecium/isolation & purification , Enterococcus faecium/physiology , Feces/microbiology , Female , Gastrointestinal Microbiome/drug effects , Humans , Intensive Care Units , Male , Meropenem/pharmacology , Meropenem/therapeutic use , Metagenomics , Middle Aged , Prospective Studies
2.
Emerg Infect Dis ; 25(6): 1245-1247, 2019 06.
Article in English | MEDLINE | ID: mdl-31107237

ABSTRACT

Molecular analysis of atypical schistosome eggs retrieved from children in Malawi revealed genetic interactions occurring between human (Schistosoma haematobium) and livestock (S. mattheei and S. bovis) schistosome species. Detection of hybrid schistosomes adds a notable new perspective to the epidemiology and control of urogenital schistosomiasis in central Africa.


Subject(s)
Schistosoma haematobium/classification , Schistosoma/classification , Schistosomiasis/epidemiology , Schistosomiasis/parasitology , Animals , Child , Humans , Livestock/parasitology , Malawi/epidemiology , Public Health Surveillance , Schistosoma/genetics , Schistosoma haematobium/genetics , Schistosomiasis/diagnosis , Schistosomiasis haematobia/diagnosis , Schistosomiasis haematobia/epidemiology , Schistosomiasis haematobia/parasitology
3.
Article in English | MEDLINE | ID: mdl-30675341

ABSTRACT

Background: Carbapenemase-producing Enterobacteriaceae (CPE) pose a considerable threat to modern medicine. New treatment options and methods to limit spread need to be investigated. Blue light (BL) is intrinsically antimicrobial, and we have previously demonstrated significant antimicrobial effects on biofilms of a panel of isolates, including two CPEs.This study was performed to assess the antibacterial activity of 405 nm BL against a panel of CPE isolates (four encoding blaNDM, three blaKPC, two blaOXA-48, and three encoding both NDM and OXA-48 carbapenemases). Methods: In vitro experiments were conducted on 72 h old biofilms of CPEs which were exposed to 60 mW/cm2 of BL. Changes to biofilm seeding were assessed by measuring the optical density of treated and untreated biofilms. Results: Twelve bacterial clinical isolates (comprising eight Klebsiella pnemoniae, one K. oxytoca, and three Escherichia coli) were tested. BL was delivered for 5, 15 and 30 min, achieving doses of 162, 54, and 108 J/cm2, respectively.All of the CPEs were susceptible to BL treatment, with increasing reductions in seeding with increasing durations of exposure. At 30 min, reductions in biofilm seeding of ≥80% were observed for 11 of the 12 isolates, compared to five of 12 after 15 min. CPE_8180 was less susceptible than the rest, with a maximum reduction in seeding of 66% at 30 min. Conclusions: BL is effective at reducing the seeding of mature CPE biofilms in vitro, and offers great promise as a topical decontamination/treatment agent for both clinical and environmental applications.


Subject(s)
Carbapenem-Resistant Enterobacteriaceae/radiation effects , Decontamination/methods , Enterobacteriaceae Infections/microbiology , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Biofilms/radiation effects , Carbapenem-Resistant Enterobacteriaceae/drug effects , Carbapenem-Resistant Enterobacteriaceae/physiology , Decontamination/instrumentation , Humans , Light , Microbial Sensitivity Tests , beta-Lactamases/genetics , beta-Lactamases/metabolism
4.
Burns ; 44(1): 39-56, 2018 02.
Article in English | MEDLINE | ID: mdl-28784345

ABSTRACT

BACKGROUND: The early diagnosis of infection or sepsis in burns are important for patient care. Globally, a large number of burn centres advocate quantitative cultures of wound biopsies for patient management, since there is assumed to be a direct link between the bioburden of a burn wound and the risk of microbial invasion. Given the conflicting study findings in this area, a systematic review was warranted. METHODS: Bibliographic databases were searched with no language restrictions to August 2015. Study selection, data extraction and risk of bias assessment were performed in duplicate using pre-defined criteria. Substantial heterogeneity precluded quantitative synthesis, and findings were described narratively, sub-grouped by clinical question. RESULTS: Twenty six laboratory and/or clinical studies were included. Substantial heterogeneity hampered comparisons across studies and interpretation of findings. Limited evidence suggests that (i) more than one quantitative microbiology sample is required to obtain reliable estimates of bacterial load; (ii) biopsies are more sensitive than swabs in diagnosing or predicting sepsis; (iii) high bacterial loads may predict worse clinical outcomes, and (iv) both quantitative and semi-quantitative culture reports need to be interpreted with caution and in the context of other clinical risk factors. CONCLUSION: The evidence base for the utility and reliability of quantitative microbiology for diagnosing or predicting clinical outcomes in burns patients is limited and often poorly reported. Consequently future research is warranted.


Subject(s)
Burns/microbiology , Wound Infection/diagnosis , Bacterial Load/methods , Biopsy , Humans , Reproducibility of Results , Sepsis/diagnosis
5.
Platelets ; 29(1): 9-20, 2018 Jan.
Article in English | MEDLINE | ID: mdl-28681651

ABSTRACT

The infection of a wound is one of the major contributors to delays in healing and tissue regeneration. As multi-drug resistance to antibiotics is becoming a serious threat, research in this field has focused on finding new agents and strategies to fight infection and additionally to reduce healing times. The topical use of autologous Platelet Rich Plasma (PRP) as a biological accelerator of the healing process, has been safely used as a form of treatment for wounds since the 1990s. Although the presence or absence of leucocytes in PRP preparation was previously neglected, in the last decade more attention has been paid to their role and several studies have been conducted to explore both their immuno-metabolic effects and their antimicrobial properties. In this review, we aim to summarise the literature on the contribution of leucocytes included in PRP preparations in terms of their antimicrobial properties. This should help to inform clinical practice and additional research in this promising field.


Subject(s)
Anti-Infective Agents , Leukocytes/immunology , Leukocytes/microbiology , Platelet-Rich Plasma/cytology , Platelet-Rich Plasma/immunology , Anti-Infective Agents/therapeutic use , Antisepsis , Bacterial Infections/immunology , Bacterial Infections/microbiology , Bacterial Infections/therapy , Biomarkers , Blood Platelets/metabolism , Humans , Leukocytes/metabolism , Platelet Activation , Treatment Outcome
6.
J Glob Antimicrob Resist ; 8: 186-191, 2017 03.
Article in English | MEDLINE | ID: mdl-28213334

ABSTRACT

Reactive oxygen species (ROS) is a novel therapeutic strategy for topical or local application to wounds, mucosa or internal structures where there may be heavy bacterial bioburden with biofilm and chronic inflammation. Bacterial biofilms are a significant problem in clinical settings owing to their increased tolerance towards conventionally prescribed antibiotics and their propensity for selection of further antibacterial resistance. There is therefore a pressing need for the development of alternative therapeutic strategies that can improve antibiotic efficacy towards biofilms. ROS has been successful in treating chronic wounds and in clearing multidrug-resistant organisms, including methicillin-resistant Staphylococcus aureus (MRSA), and carbapenemase-producing isolates from wounds and vascular line sites. There is significant antifungal activity of ROS against planktonic and biofilm forms. Nebulised ROS has been evaluated in limited subjects to assess reductions in bioburden in chronically colonised respiratory tracts. The antibiofilm activity of ROS could have great implications for the treatment of a variety of persistent respiratory conditions. Use of ROS on internal prosthetic devices shows promise. A variety of novel delivery mechanisms are being developed to apply ROS activity to different anatomical sites.


Subject(s)
Anti-Infective Agents, Local/therapeutic use , Bacteria/drug effects , Bacterial Infections/drug therapy , Biofilms/drug effects , Reactive Oxygen Species/therapeutic use , Wound Infection/drug therapy , Administration, Topical , Animals , Drug Evaluation, Preclinical , Fungi/drug effects , Humans
7.
J R Soc Interface ; 14(126)2017 01.
Article in English | MEDLINE | ID: mdl-28077764

ABSTRACT

The interface between implanted devices and their host tissue is complex and is often optimized for maximal integration and cell adhesion. However, this also gives a surface suitable for bacterial colonization. We have developed a novel method of modifying the surface at the material-tissue interface with an antimicrobial peptide (AMP) coating to allow cell attachment while inhibiting bacterial colonization. The technology reported here is a dual AMP coating. The dual coating consists of AMPs covalently bonded to the hydroxyapatite surface, followed by deposition of electrostatically bound AMPs. The dual approach gives an efficacious coating which is stable for over 12 months and can prevent colonization of the surface by both Gram-positive and Gram-negative bacteria.


Subject(s)
Antimicrobial Cationic Peptides/chemistry , Coated Materials, Biocompatible/chemistry , Durapatite/chemistry , Materials Testing , Osteoblasts/metabolism , Animals , Cell Line , Gram-Negative Bacteria/growth & development , Gram-Positive Bacteria/growth & development , Mice , Osteoblasts/cytology , Static Electricity
8.
Appl Environ Microbiol ; 82(13): 4006-4016, 2016 07 01.
Article in English | MEDLINE | ID: mdl-27129967

ABSTRACT

UNLABELLED: The blue wavelengths within the visible light spectrum are intrinisically antimicrobial and can photodynamically inactivate the cells of a wide spectrum of bacteria (Gram positive and negative) and fungi. Furthermore, blue light is equally effective against both drug-sensitive and -resistant members of target species and is less detrimental to mammalian cells than is UV radiation. Blue light is currently used for treating acnes vulgaris and Helicobacter pylori infections; the utility for decontamination and treatment of wound infections is in its infancy. Furthermore, limited studies have been performed on bacterial biofilms, the key growth mode of bacteria involved in clinical infections. Here we report the findings of a multicenter in vitro study performed to assess the antimicrobial activity of 400-nm blue light against bacteria in both planktonic and biofilm growth modes. Blue light was tested against a panel of 34 bacterial isolates (clinical and type strains) comprising Acinetobacter baumannii, Enterobacter cloacae, Stenotrophomonas maltophilia, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Enterococcus faecium, Klebsiella pneumoniae, and Elizabethkingia meningoseptica All planktonic-phase bacteria were susceptible to blue light treatment, with the majority (71%) demonstrating a ≥5-log10 decrease in viability after 15 to 30 min of exposure (54 J/cm(2) to 108 J/cm(2)). Bacterial biofilms were also highly susceptible to blue light, with significant reduction in seeding observed for all isolates at all levels of exposure. These results warrant further investigation of blue light as a novel decontamination strategy for the nosocomial environment, as well as additional wider decontamination applications. IMPORTANCE: Blue light shows great promise as a novel decontamination strategy for the nosocomial environment, as well as additional wider decontamination applications (e.g., wound closure during surgery). This warrants further investigation.


Subject(s)
Bacteria/drug effects , Biofilms/drug effects , Light , Microbial Viability/drug effects , Colony Count, Microbial , Wounds and Injuries/microbiology
9.
J Infect Dis ; 213(11): 1743-51, 2016 Jun 01.
Article in English | MEDLINE | ID: mdl-26908756

ABSTRACT

BACKGROUND: Models of controlled human malaria infection (CHMI) initiated by mosquito bite have been widely used to assess efficacy of preerythrocytic vaccine candidates in small proof-of-concept phase 2a clinical trials. Efficacy testing of blood-stage malaria parasite vaccines, however, has generally relied on larger-scale phase 2b field trials in malaria-endemic populations. We report the use of a blood-stage P. falciparum CHMI model to assess blood-stage vaccine candidates, using their impact on the parasite multiplication rate (PMR) as the primary efficacy end point. METHODS: Fifteen healthy United Kingdom adult volunteers were vaccinated with FMP2.1, a protein vaccine that is based on the 3D7 clone sequence of apical membrane antigen 1 (AMA1) and formulated in Adjuvant System 01 (AS01). Twelve vaccinees and 15 infectivity controls subsequently underwent blood-stage CHMI. Parasitemia was monitored by quantitative real-time polymerase chain reaction (PCR) analysis, and PMR was modeled from these data. RESULTS: FMP2.1/AS01 elicited anti-AMA1 T-cell and serum antibody responses. Analysis of purified immunoglobulin G showed functional growth inhibitory activity against P. falciparum in vitro. There were no vaccine- or CHMI-related safety concerns. All volunteers developed blood-stage parasitemia, with no impact of the vaccine on PMR. CONCLUSIONS: FMP2.1/AS01 demonstrated no efficacy after blood-stage CHMI. However, the model induced highly reproducible infection in all volunteers and will accelerate proof-of-concept testing of future blood-stage vaccine candidates. CLINICAL TRIALS REGISTRATION: NCT02044198.


Subject(s)
Antigens, Protozoan/immunology , Malaria Vaccines/immunology , Malaria, Falciparum/prevention & control , Membrane Proteins/immunology , Plasmodium falciparum/immunology , Protozoan Proteins/immunology , Adult , Enzyme-Linked Immunospot Assay , Erythrocytes/parasitology , Female , Humans , Immunogenicity, Vaccine , Life Cycle Stages , Malaria, Falciparum/parasitology , Male , Middle Aged , Models, Biological , Plasmodium falciparum/physiology , Young Adult
10.
Syst Rev ; 4: 150, 2015 Nov 06.
Article in English | MEDLINE | ID: mdl-26542240

ABSTRACT

BACKGROUND: Sepsis from burn injuries can result from colonisation of burn wounds, especially in large surface area burns. Reducing bacterial infection will reduce morbidity and mortality, and mortality for severe burns can be as high as 15 %. There are various quantitative and semi-quantitative techniques to monitor bacterial load on wounds. In the UK, burn wounds are typically monitored for the presence or absence of bacteria through the collection and culture of swabs, but no absolute count is obtained. Quantitative burn wound culture provides a measure of bacterial count and is gaining increased popularity in some countries. It is however more resource intensive, and evidence for its utility appears to be inconsistent. This systematic review therefore aims to assess the evidence on the utility and reliability of different quantitative microbiology techniques in terms of diagnosing or predicting clinical outcomes. METHODS/DESIGN: Standard systematic review methods aimed at minimising bias will be employed for study identification, selection and data extraction. Bibliographic databases and ongoing trial registers will be searched and conference abstracts screened. Studies will be eligible if they are prospective studies or systematic reviews of burn patients (any age) for whom quantitative microbiology has been performed, whether it is compared to another method. Quality assessment will be based on quality assessment tools for diagnostic and prognostic studies and tailored to the review as necessary. Synthesis is likely to be primarily narrative, but meta-analysis may be considered where clinical and methodological homogeneity exists. DISCUSSION: Given the increasing use of quantitative methods, this is a timely systematic review, which will attempt to clarify the evidence base. As far as the authors are aware, it will be the first to address this topic. TRIAL REGISTRATION: PROSPERO, CRD42015023903.


Subject(s)
Bacterial Infections/diagnosis , Bacterial Infections/prevention & control , Bacterial Load , Burns/microbiology , Burns/therapy , Bacterial Infections/complications , Colony Count, Microbial , Humans , Research Design , Sepsis/microbiology , Systematic Reviews as Topic
11.
PLoS One ; 10(9): e0136190, 2015.
Article in English | MEDLINE | ID: mdl-26352256

ABSTRACT

INTRODUCTION: Localised infections, and burn wound sepsis are key concerns in the treatment of burns patients, and prevention of colonisation largely relies on biocides. Acetic acid has been shown to have good antibacterial activity against various planktonic organisms, however data is limited on efficacy, and few studies have been performed on biofilms. OBJECTIVES: We sought to investigate the antibacterial activity of acetic acid against important burn wound colonising organisms growing planktonically and as biofilms. METHODS: Laboratory experiments were performed to test the ability of acetic acid to inhibit growth of pathogens, inhibit the formation of biofilms, and eradicate pre-formed biofilms. RESULTS: Twenty-nine isolates of common wound-infecting pathogens were tested. Acetic acid was antibacterial against planktonic growth, with an minimum inhibitory concentration of 0.16-0.31% for all isolates, and was also able to prevent formation of biofilms (at 0.31%). Eradication of mature biofilms was observed for all isolates after three hours of exposure. CONCLUSIONS: This study provides evidence that acetic acid can inhibit growth of key burn wound pathogens when used at very dilute concentrations. Owing to current concerns of the reducing efficacy of systemic antibiotics, this novel biocide application offers great promise as a cheap and effective measure to treat infections in burns patients.


Subject(s)
Acetic Acid/pharmacology , Bacteria/drug effects , Biofilms/drug effects , Burns/microbiology , Disinfectants/pharmacology , Bacteria/isolation & purification , Bacteria/pathogenicity , Cross Infection/microbiology , Drug Evaluation, Preclinical , Humans , Microbial Sensitivity Tests , Time Factors , Wound Infection/prevention & control
12.
Burns ; 41(8): 1683-1694, 2015 Dec.
Article in English | MEDLINE | ID: mdl-26188884

ABSTRACT

UNLABELLED: Antimicrobial medicated dressings (AMD) are often used to reduce bacterial infection of burns and other wounds. However, there is limited literature regarding comparative efficacies to inform effective clinical decision making. OBJECTIVES: Following on from a previous study where we demonstrated good antibiofilm properties of acetic acid (AA), we assessed and compared the in vitro anti-biofilm activity of a range of AMDs and non-AMDs to AA. METHODS: Laboratory experiments determined the ability of a range of eleven commercial AMD, two nAMD, and AA, to prevent the formation of biofilms of a panel of four isolates of Pseudomonas aeruginosa and Acinetobacter baumannii. RESULTS: There is a large variation in ability of different dressings to inhibit biofilm formation, seen between dressings that contain the same, and those that contain other antimicrobial agents. The best performing AMD were Mepilex(®) Ag and Acticoat. AA consistently prevented biofilm formation. CONCLUSIONS: Large variation exists in the ability of AMD to prevent biofilm formation and colonisation of wounds. A standardised in vitro methodology should be developed for external parties to examine and compare the efficacies of commercially available AMDs, along with robust clinical randomised controlled trials. This is essential for informed clinical decision-making and optimal patient management.


Subject(s)
Acinetobacter baumannii/drug effects , Anti-Bacterial Agents/pharmacology , Bandages , Biofilms/drug effects , Burns/therapy , Pseudomonas aeruginosa/drug effects , Acetic Acid/pharmacology , Acetic Acid/therapeutic use , Acinetobacter Infections/prevention & control , Acinetobacter baumannii/growth & development , Anti-Bacterial Agents/therapeutic use , Biofilms/growth & development , Burns/microbiology , Chlorhexidine/pharmacology , Chlorhexidine/therapeutic use , Honey , In Vitro Techniques , Iodine/pharmacology , Iodine/therapeutic use , Microbial Sensitivity Tests , Polyesters/therapeutic use , Polyethylenes/therapeutic use , Pseudomonas Infections/prevention & control , Pseudomonas aeruginosa/growth & development , Silver/pharmacology , Silver/therapeutic use , Wound Infection/prevention & control
13.
PLoS One ; 9(9): e107903, 2014.
Article in English | MEDLINE | ID: mdl-25254500

ABSTRACT

The development of protective vaccines against many difficult infectious pathogens will necessitate the induction of effective antibody responses. Here we assess humoral immune responses against two antigens from the blood-stage merozoite of the Plasmodium falciparum human malaria parasite--MSP1 and AMA1. These antigens were delivered to healthy malaria-naïve adult volunteers in Phase Ia clinical trials using recombinant replication-deficient viral vectors--ChAd63 to prime the immune response and MVA to boost. In subsequent Phase IIa clinical trials, immunized volunteers underwent controlled human malaria infection (CHMI) with P. falciparum to assess vaccine efficacy, whereby all but one volunteer developed low-density blood-stage parasitemia. Here we assess serum antibody responses against both the MSP1 and AMA1 antigens following i) ChAd63-MVA immunization, ii) immunization and CHMI, and iii) primary malaria exposure in the context of CHMI in unimmunized control volunteers. Responses were also assessed in a cohort of naturally-immune Kenyan adults to provide comparison with those induced by a lifetime of natural malaria exposure. Serum antibody responses against MSP1 and AMA1 were characterized in terms of i) total IgG responses before and after CHMI, ii) responses to allelic variants of MSP1 and AMA1, iii) functional growth inhibitory activity (GIA), iv) IgG avidity, and v) isotype responses (IgG1-4, IgA and IgM). These data provide the first in-depth assessment of the quality of adenovirus-MVA vaccine-induced antibody responses in humans, along with assessment of how these responses are modulated by subsequent low-density parasite exposure. Notable differences were observed in qualitative aspects of the human antibody responses against these malaria antigens depending on the means of their induction and/or exposure of the host to the malaria parasite. Given the continued clinical development of viral vectored vaccines for malaria and a range of other diseases targets, these data should help to guide further immuno-monitoring studies of vaccine-induced human antibody responses.


Subject(s)
Adenoviridae/immunology , Antigens, Protozoan/immunology , Immunity, Humoral/immunology , Malaria Vaccines/immunology , Malaria, Falciparum/prevention & control , Vaccination/methods , Vaccinia virus/immunology , Adenoviridae/genetics , Animals , Antibodies, Protozoan/blood , Antibodies, Protozoan/immunology , Blood/parasitology , Environmental Exposure/adverse effects , Humans , Immunoglobulin G/biosynthesis , Immunoglobulin G/immunology , Malaria Vaccines/genetics , Malaria, Falciparum/blood , Malaria, Falciparum/immunology , Pan troglodytes , Plasmodium falciparum/immunology , Plasmodium falciparum/physiology , Species Specificity , Vaccinia virus/genetics
14.
Immunology ; 141(4): 628-44, 2014 Apr.
Article in English | MEDLINE | ID: mdl-24303947

ABSTRACT

Acquisition of non-sterilizing natural immunity to Plasmodium falciparum malaria has been shown in low transmission areas following multiple exposures. However, conflicting data from endemic areas suggest that the parasite may interfere with the induction of effective B-cell responses. To date, the impact of blood-stage parasite exposure on antigen-specific B cells has not been reported following controlled human malaria infection (CHMI). Here we analysed human B-cell responses in a series of Phase I/IIa clinical trials, which include CHMI, using candidate virus-vectored vaccines encoding two blood-stage antigens: merozoite surface protein 1 (MSP1) and apical membrane antigen 1 (AMA1). Previously vaccinated volunteers show boosting of pre-existing antigen-specific memory B-cell (mBC) responses following CHMI. In contrast, unvaccinated malaria-naive control volunteers developed an mBC response against MSP1 but not AMA1. Serum IgG correlated with the mBC response after booster vaccination but this relationship was less well maintained following CHMI. A significant reduction in peripheral MSP1-specific mBC was observed at the point of diagnosis of blood-stage infection. This was coincident with a reduction in peripheral blood B-cell subsets expressing CXCR3 and elevated serum levels of interferon-γ and CXCL9, suggesting migration away from the periphery. These CHMI data confirm that mBC and antibody responses can be induced and boosted by blood-stage parasite exposure, in support of epidemiological studies on low-level parasite exposure.


Subject(s)
Adenoviridae/genetics , Antigens, Protozoan/administration & dosage , B-Lymphocytes/drug effects , Immunization , Malaria Vaccines/administration & dosage , Malaria, Falciparum/prevention & control , Membrane Proteins/administration & dosage , Merozoite Surface Protein 1/administration & dosage , Plasmodium falciparum/drug effects , Protozoan Proteins/administration & dosage , Vaccinia virus/genetics , Antibodies, Protozoan/blood , Antigens, Protozoan/genetics , Antigens, Protozoan/immunology , B-Lymphocytes/immunology , B-Lymphocytes/metabolism , B-Lymphocytes/parasitology , Chemokine CXCL9/blood , Genetic Vectors , Humans , Immunization Schedule , Immunization, Secondary , Immunoglobulin G/blood , Immunologic Memory , Interferon-gamma/blood , Malaria Vaccines/genetics , Malaria Vaccines/immunology , Malaria, Falciparum/blood , Malaria, Falciparum/diagnosis , Malaria, Falciparum/immunology , Malaria, Falciparum/parasitology , Membrane Proteins/genetics , Membrane Proteins/immunology , Merozoite Surface Protein 1/genetics , Merozoite Surface Protein 1/immunology , Plasmodium falciparum/growth & development , Plasmodium falciparum/immunology , Protozoan Proteins/genetics , Protozoan Proteins/immunology , Receptors, CXCR3/blood , Time Factors
15.
Nat Commun ; 4: 2836, 2013.
Article in English | MEDLINE | ID: mdl-24284865

ABSTRACT

Induction of antigen-specific CD8(+) T cells offers the prospect of immunization against many infectious diseases, but no subunit vaccine has induced CD8(+) T cells that correlate with efficacy in humans. Here we demonstrate that a replication-deficient chimpanzee adenovirus vector followed by a modified vaccinia virus Ankara booster induces exceptionally high frequency T-cell responses (median >2400 SFC/10(6) peripheral blood mononuclear cells) to the liver-stage Plasmodium falciparum malaria antigen ME-TRAP. It induces sterile protective efficacy against heterologous strain sporozoites in three vaccinees (3/14, 21%), and delays time to patency through substantial reduction of liver-stage parasite burden in five more (5/14, 36%), P=0.008 compared with controls. The frequency of monofunctional interferon-γ-producing CD8(+) T cells, but not antibodies, correlates with sterile protection and delay in time to patency (P(corrected)=0.005). Vaccine-induced CD8(+) T cells provide protection against human malaria, suggesting that a major limitation of previous vaccination approaches has been the insufficient magnitude of induced T cells.


Subject(s)
Adenoviruses, Simian/immunology , CD8-Positive T-Lymphocytes/immunology , Malaria Vaccines/immunology , Malaria, Falciparum/prevention & control , Vaccinia virus/immunology , Adenoviruses, Simian/genetics , Adolescent , Adult , Animals , Antibodies, Protozoan/immunology , Female , Genetic Vectors/genetics , Genetic Vectors/immunology , Humans , Immunity, Cellular , Immunization , Immunization, Secondary , Interferon-gamma/immunology , Leukocytes, Mononuclear , Malaria Vaccines/administration & dosage , Malaria Vaccines/genetics , Malaria, Falciparum/immunology , Malaria, Falciparum/parasitology , Male , Middle Aged , Plasmodium falciparum/genetics , Plasmodium falciparum/immunology , Protozoan Proteins/genetics , Protozoan Proteins/immunology , Vaccinia virus/genetics , Young Adult
16.
J Med Microbiol ; 62(Pt 10): 1535-1539, 2013 Oct.
Article in English | MEDLINE | ID: mdl-23831766

ABSTRACT

A universal stool extraction method for recovery of nucleic acids (NAs) from gastrointestinal pathogens was developed to support rapid diagnostics for the London 2012 Olympics. The method involved mechanical disruption (bead beating) of the stools, followed by automated extraction and detection using real-time PCR. This method had been used extensively in the Second Infectious Intestinal Disease Study (IID2) for the isolation of NA from bacteria and parasites (and was effective for the robust recovery of Cryptosporidium spp.) but had not been used for enteric viruses. To ensure this method was universally suitable, panels of samples known to contain target bacteria, viruses or parasites were processed in triplicate using the pre-treatment method routinely used for each target and the new extraction method (bead beating). The extracts were tested using real-time PCR and the cycle threshold values were compared. The results from this study showed that bead beating improved yields for the bacterial and parasitic targets and was suitable for the viral targets. The implementation of this universal method should confer cost- and time-saving benefits and streamline the processes required for the characterization of an array of pathogens from faecal samples.


Subject(s)
DNA/isolation & purification , Feces/microbiology , Feces/parasitology , Gastroenteritis/etiology , Molecular Diagnostic Techniques/methods , Real-Time Polymerase Chain Reaction/methods , Specimen Handling/methods , Bacterial Infections/diagnosis , DNA/genetics , Humans , Intestinal Diseases, Parasitic/diagnosis , London , Molecular Diagnostic Techniques/economics , Real-Time Polymerase Chain Reaction/economics , Specimen Handling/economics , Time Factors
17.
J Immunol ; 190(3): 1135-47, 2013 Feb 01.
Article in English | MEDLINE | ID: mdl-23293353

ABSTRACT

Overcoming antigenic variation is one of the major challenges in the development of an effective vaccine against Plasmodium falciparum, a causative agent of human malaria. Inclusion of multiple Ag variants in subunit vaccine candidates is one strategy that has aimed to overcome this problem for the leading blood-stage malaria vaccine targets, that is, merozoite surface protein 1 (MSP1) and apical membrane Ag 1 (AMA1). However, previous studies, utilizing malaria Ags, have concluded that inclusion of multiple allelic variants, encoding altered peptide ligands, in such a vaccine may be detrimental to both the priming and in vivo restimulation of Ag-experienced T cells. In this study, we analyze the T cell responses to two alleles of MSP1 and AMA1 induced by vaccination of malaria-naive adult volunteers with bivalent viral-vectored vaccine candidates. We show a significant bias to the 3D7/MAD20 allele compared with the Wellcome allele for the 33 kDa region of MSP1, but not for the 19 kDa fragment or the AMA1 Ag. Although this bias could be caused by "immune interference" at priming, the data do not support a significant role for "immune antagonism" during memory T cell restimulation, despite observation of the latter at a minimal epitope level in vitro. A lack of class I HLA epitopes in the Wellcome allele that are recognized by vaccinated volunteers may in fact contribute to the observed bias. We also show that controlled infection with 3D7 strain P. falciparum parasites neither boosts existing 3D7-specific T cell responses nor appears to "immune divert" cellular responses toward the Wellcome allele.


Subject(s)
Antigens, Protozoan/immunology , Immunologic Memory/immunology , Malaria Vaccines/immunology , Membrane Proteins/immunology , Merozoite Surface Protein 1/immunology , Plasmodium falciparum/immunology , Protozoan Proteins/immunology , T-Lymphocytes/immunology , Adenoviridae/genetics , Adult , Alleles , Antibodies, Protozoan/immunology , Antigenic Variation/genetics , Antigens, Protozoan/genetics , Defective Viruses/genetics , Epitopes/immunology , Erythrocytes/parasitology , Genetic Vectors/administration & dosage , Genetic Vectors/genetics , HLA Antigens/immunology , Humans , Interferon-gamma/biosynthesis , Malaria, Falciparum/immunology , Malaria, Falciparum/prevention & control , Membrane Proteins/genetics , Merozoite Surface Protein 1/genetics , Peptide Fragments/genetics , Peptide Fragments/immunology , Plasmodium falciparum/genetics , Plasmodium falciparum/growth & development , Protozoan Proteins/genetics , Vaccination , Vaccines, Subunit/immunology , Vaccinia virus/genetics
18.
Mol Ther ; 20(12): 2355-68, 2012 Dec.
Article in English | MEDLINE | ID: mdl-23089736

ABSTRACT

The induction of cellular immunity, in conjunction with antibodies, may be essential for vaccines to protect against blood-stage infection with the human malaria parasite Plasmodium falciparum. We have shown that prime-boost delivery of P. falciparum blood-stage antigens by chimpanzee adenovirus 63 (ChAd63) followed by the attenuated orthopoxvirus MVA is safe and immunogenic in healthy adults. Here, we report on vaccine efficacy against controlled human malaria infection delivered by mosquito bites. The blood-stage malaria vaccines were administered alone, or together (MSP1+AMA1), or with a pre-erythrocytic malaria vaccine candidate (MSP1+ME-TRAP). In this first human use of coadministered ChAd63-MVA regimes, we demonstrate immune interference whereby responses against merozoite surface protein 1 (MSP1) are dominant over apical membrane antigen 1 (AMA1) and ME-TRAP. We also show that induction of strong cellular immunity against MSP1 and AMA1 is safe, but does not impact on parasite growth rates in the blood. In a subset of vaccinated volunteers, a delay in time to diagnosis was observed and sterilizing protection was observed in one volunteer coimmunized with MSP1+AMA1-results consistent with vaccine-induced pre-erythrocytic, rather than blood-stage, immunity. These data call into question the utility of T cell-inducing blood-stage malaria vaccines and suggest that the focus should remain on high-titer antibody induction against susceptible antigen targets.


Subject(s)
Antigens, Protozoan/immunology , Culicidae/parasitology , Culicidae/pathogenicity , Malaria Vaccines/therapeutic use , Merozoite Surface Protein 1/immunology , Adenoviruses, Simian/genetics , Animals , Flow Cytometry , Humans , Malaria Vaccines/administration & dosage , Malaria, Falciparum/immunology , Malaria, Falciparum/prevention & control , Orthopoxvirus/immunology , Pan troglodytes/virology
20.
Clin Infect Dis ; 54(9): 1275-86, 2012 May.
Article in English | MEDLINE | ID: mdl-22412058

ABSTRACT

BACKGROUND: Large-scale, prospective studies of infectious intestinal disease (IID) in developed countries are uncommon. Two studies of IID incidence and etiology have been conducted in the United Kingdom: the Infectious Intestinal Disease Study in England (IID1) in 1993-1996 and the Second Study of Infectious Intestinal Disease in the Community (IID2) in 2008-2009. We examined changes in etiology and diagnostic yield of IID cases over 15 years. METHODS: Fecal samples submitted by IID cases were examined for a range of bacterial, viral, and protozoal pathogens using traditional and molecular microbiological methods. We calculated the percentage of specimens positive for each organism based on traditional methods and on traditional and molecular methods combined. We compared the distributions of organisms in the 2 studies. RESULTS: For pathogens investigated in both studies, 40% of fecal samples submitted by cases in IID2 were positive compared with 28% in IID1. Viruses were most frequent among community cases in IID2. Campylobacter was the most common bacterial pathogen among cases presenting to healthcare. Major differences between the 2 studies were increases in the detection of norovirus and sapovirus and a decline Salmonella. CONCLUSIONS: Most fecal specimens were negative for the pathogens tested in both studies, so new strategies are needed to close the diagnostic gap. Among known pathogens, effective control of norovirus, rotavirus, and Campylobacter remain high priorities. The reduction in nontyphoidal salmonellosis demonstrates the success of Europe-wide control strategies, notably an industry-led Salmonella control program in poultry in the United Kingdom.


Subject(s)
Caliciviridae Infections/epidemiology , Campylobacter Infections/epidemiology , Gastroenteritis/epidemiology , Salmonella Infections/epidemiology , Adolescent , Adult , Aged , Aged, 80 and over , Caliciviridae Infections/diagnosis , Caliciviridae Infections/virology , Campylobacter/isolation & purification , Campylobacter Infections/diagnosis , Campylobacter Infections/microbiology , Child , Child, Preschool , Cohort Studies , Coinfection , Feces/microbiology , Feces/parasitology , Feces/virology , Gastroenteritis/diagnosis , Gastroenteritis/microbiology , Gastroenteritis/virology , Humans , Incidence , Infant , Middle Aged , Norovirus/isolation & purification , Prospective Studies , Salmonella/isolation & purification , Salmonella Infections/diagnosis , Salmonella Infections/microbiology , Sapovirus/isolation & purification , United Kingdom/epidemiology , Young Adult
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