Publications by authors named "Achim Hoerauf"

255 Publications

Podoconiosis - From known to unknown: Obstacles to tackle.

Acta Trop 2021 Jul 9;219:105918. Epub 2021 Apr 9.

Institute for Medical Microbiology, Immunology and Parasitology (IMMIP), University Hospital Bonn (UKB), Bonn, Germany. Electronic address:

Podoconiosis is a non-filarial and non-communicable disease leading to lymphedema of the lower limbs. Worldwide, 4 million individuals live with podoconiosis, which is accompanied by disability and painful intermittent acute inflammatory episodes that attribute to significant disability adjusted life years (DALYs). Different risk factors like contact with volcanic red clay soil, high altitude (above 1000 m), high seasonal rainfall (above 1000 mm/year) and occupation (e.g., subsistence farmer) are associated with the risk of podoconiosis. Although podoconiosis was described to be endemic in 32 countries in Africa, parts of Latin America and South East Asia, knowledge about related genetics, pathophysiology, immunology and especially the causing molecule(s) in the soil remain uncertain. Thus, podoconiosis can be considered as one of the most neglected diseases. This review provides an overview about this non-filarial related geochemical disease and aim to present perspectives and future directions that might be important for better understanding of the disease, prospect for point-of-care diagnosis, achieving protection and developing novel treatment strategies.
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http://dx.doi.org/10.1016/j.actatropica.2021.105918DOI Listing
July 2021

Rapid diagnostic test negative Plasmodium falciparum malaria in a traveller returning from Ethiopia.

Malar J 2021 Mar 12;20(1):145. Epub 2021 Mar 12.

Department of Internal Medicine I, University Hospital of Bonn, Venusberg Campus 1, Building 26, 53127, Bonn, Germany.

Background: Plasmodium falciparum strains with mutations/deletions of the genes encoding the histidine-rich proteins 2/3 (pfhrp2/3) have emerged during the last 10 years leading to false-negative results in HRP2-based rapid diagnostic tests (RDTs). This can lead to unrecognized infections in individuals and to setbacks in malaria control in endemic countries where RDTs are the backbone of malaria diagnostics and control.

Case Description: Here the detection of a pfhrp2/3-negative P. falciparum infection acquired in Ethiopia by a 63-year old female traveller is presented. After onset of symptoms during travel, she was first tested negative for malaria, most probably by RDT, at a local hospital in Harar, Ethiopia. Falciparum malaria was finally diagnosed microscopically upon her return to Germany, over 4 weeks after infection. At a parasite density of approximately 5387 parasites/µl, two different high-quality RDTs: Palutop + 4 OPTIMA, NADALMalaria PF/pan Ag 4 Species, did not respond at their respective P. falciparum test lines. pfhrp2/3 deletion was confirmed by multiplex-PCR. The patient recovered after a complete course of atovaquone and proguanil. According to the travel route, malaria was acquired most likely in the Awash region, Central Ethiopia. This is the first case of imported P. falciparum with confirmed pfhrp2/3 deletion from Ethiopia.

Conclusion: HRP2-negative P. falciparum strains may not be recognized by the presently available HRP2-based RDTs. When malaria is suspected, confirmation by microscopy and/or qPCR is necessary in order to detect falciparum malaria, which requires immediate treatment. This case of imported P. falciparum, non-reactive to HRP2-based RDT, possibly underlines the necessity for standardized, nationwide investigations in Ethiopia and should alert clinicians from non-endemic countries to the possibility of false-negative RDT results which may increase in returning travellers with potentially life-threatening infections.
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http://dx.doi.org/10.1186/s12936-021-03678-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7952815PMC
March 2021

Flow cytometric analysis of cell lineage and immune activation markers using minimal amounts of human whole blood-Field method for remote settings.

J Immunol Methods 2021 Apr 9;491:112989. Epub 2021 Feb 9.

Division of Infectious Diseases and Tropical Medicine, LMU University Hospital Munich, Germany; German Center for Infection Research (DZIF), Munich, Germany. Electronic address:

Remote laboratory settings - such as those where studies on neglected tropical diseases are performed - often lack specialized equipment required for flow cytometric analysis of immune cell subsets, which complicates evaluations on a single cell level using peripheral blood. Our aim was to establish a method to use whole blood for phenotypic characterization of T-cells for specific markers including CD3, CD4, HLA-DR, CD38, CCR5, CD27, CD45RA, CD25, and FoxP3. This method uses 100 μL whole blood which is stained for extracellular markers, lysed, and cryopreserved at -20 °C at a field laboratory before transferring to liquid nitrogen for long-term storage and transportation. Cells can then be transported to a central laboratory for flow cytometry analysis. The method was initially established using samples from healthy donors; expression levels after cryopreservation were comparable to fresh whole blood samples from the same individuals. Moreover, data sets were also comparable to those which were stored in liquid nitrogen for up to one year. The method was then transferred to field studies in a remote area of Ghana which was used to observe its practicality and robustness in limited resource settings. Collectively, the low amount of whole blood (such as that taken from a finger prick), lack of any specialized equipment, and ease of use make this method suitable for utilization in remote field locations.
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http://dx.doi.org/10.1016/j.jim.2021.112989DOI Listing
April 2021

Establishment of an in vitro culture system to study the developmental biology of Onchocerca volvulus with implications for anti-Onchocerca drug discovery and screening.

PLoS Negl Trop Dis 2021 02 9;15(2):e0008513. Epub 2021 Feb 9.

Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.

Background: Infections with Onchocerca volvulus nematodes remain a threat in Sub-Saharan Africa after three decades of ivermectin mass drug administration. Despite this effort, there is still an urgent need for understanding the parasite biology especially the mating behaviour and nodule formation as well as the development of more potent drugs that can clear the developmental (L3, L4, L5) and adult stages of the parasite and inhibit parasite reproduction and behaviour.

Methodology/principal Findings: Prior to culture, freshly harvested O. volvulus L3 larvae from dissected Simulium damnosum flies were purified by centrifugation using a 30% Percoll solution to eliminate fly tissue debris and contaminants. Parasites were cultured in both cell-free and cell-based co-culture systems and monitored daily by microscopic visual inspection. Exhausted culture medium was replenished every 2-3 days. The cell-free culture system (DMEM supplemented with 10% NCS) supported the viability and motility of O. volvulus larvae for up to 84 days, while the co-culture system (DMEM supplemented with 10% FBS and seeded on LLC-MK2 feeder cells) extended worm survival for up to 315 days. Co-culture systems alone promoted two consecutive parasite moults (L3 to L4 and L4 to L5) with highest moulting rates (69.2±30%) observed in DMEM supplemented with 10% FBS and seeded on LLC-MK2 feeder cells, while no moult was observed in DMEM supplemented with 10% NCS and seeded on LEC feeder cells. In DMEM supplemented with 10% FBS and seeded on LLC-MK2 feeder cells, O. volvulus adult male worms attached to the vulva region of adult female worms and may have mated in vitro. Apparent early initiation of nodulogenesis was observed in both DMEM supplemented with 10% FBS and seeded on LLC-MK2 and DMEM supplemented with 10% NCS and seeded on LLC-MK2 systems.

Conclusions/significance: The present study describes an in vitro system in which O. volvulus L3 larvae can be maintained in culture leading to the development of adult stages. Thus, this in vitro system may provide a platform to investigate mating behaviour and early stage of nodulogenesis of O. volvulus adult worms that can be used as additional targets for macrofilaricidal drug screening.
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http://dx.doi.org/10.1371/journal.pntd.0008513DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7899360PMC
February 2021

Human filariasis-contributions of the Litomosoides sigmodontis and Acanthocheilonema viteae animal model.

Parasitol Res 2021 Feb 6. Epub 2021 Feb 6.

Institute for Medical Microbiology, Immunology and Parasitology (IMMIP), University Hospital Bonn, Bonn, Germany.

Filariae are vector-borne parasitic nematodes that are endemic worldwide, in tropical and subtropical regions. Important human filariae spp. include Onchocerca volvulus, Wuchereria bancrofti and Brugia spp., and Loa loa and Mansonella spp. causing onchocerciasis (river blindness), lymphatic filariasis (lymphedema and hydrocele), loiasis (eye worm), and mansonelliasis, respectively. It is estimated that over 1 billion individuals live in endemic regions where filarial diseases are a public health concern contributing to significant disability adjusted life years (DALYs). Thus, efforts to control and eliminate filarial diseases were already launched by the WHO in the 1970s, especially against lymphatic filariasis and onchocerciasis, and are mainly based on mass drug administration (MDA) of microfilaricidal drugs (ivermectin, diethylcarbamazine, albendazole) to filarial endemic areas accompanied with vector control strategies with the goal to reduce the transmission. With the United Nations Sustainable Development Goals (SDGs), it was decided to eliminate transmission of onchocerciasis and stop lymphatic filariasis as a public health problem by 2030. It was also requested that novel drugs and treatment strategies be developed. Mouse models provide an important platform for anti-filarial drug research in a preclinical setting. This review presents an overview about the Litomosoides sigmodontis and Acanthocheilonema viteae filarial mouse models and their role in immunological research as well as preclinical studies about novel anti-filarial drugs and treatment strategies.
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http://dx.doi.org/10.1007/s00436-020-07026-2DOI Listing
February 2021

The Mbam drainage system and onchocerciasis transmission post ivermectin mass drug administration (MDA) campaign, Cameroon.

PLoS Negl Trop Dis 2021 01 19;15(1):e0008926. Epub 2021 Jan 19.

Parasites and Vector Biology Research Unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon.

Background: The impact of large scale Mass Drug Adminstration (MDA) of ivermectin on active onchocerciasis transmission by Simulium damnosum, which transmits the parasite O. volvulus is of great importance for onchocerciasis control programmes. We investigated in the Mbam river system area, the impact of MDA of ivermectin on entomological indices and also verify if there are river system factors that could have favoured the transmission of onchocerciasis in this area and contribute to the persistence of disease. We compared three independent techniques to detect Onchocerca larvae in blackflies and also analyzed the river system within 9 months post-MDA of ivermectin.

Method: Simulium flies were captured before and after 1, 3, 6 and 9months of ivermectin-MDA. The biting rate was determined and 41% of the flies dissected while the rest were grouped into pools of 100 flies for DNA extraction. The extracted DNA was then subjected to O-150 LAMP and real-time PCR for the detection of infection by Onchocerca species using pool screening. The river system was analysed and the water discharge compared between rainy and dry seasons.

Principal Findings: We used human landing collection method (previously called human bait) to collect 22,274 adult female Simulium flies from Mbam River System. Of this number, 9,134 were dissected while 129 pools constituted for molecular screening. Overall biting and parous rates of 1113 flies/man/day and 24.7%, respectively, were observed. All diagnostic techniques detected similar rates of O. volvulus infection (P = 0.9252) and infectivity (P = 0.4825) at all monitoring time points. Onchocerca ochengi larvae were only detected in 2 of the 129 pools. Analysis of the river drainage revealed two hydroelectric dams constructed on the tributaries of the Mbam river were the key contributing factor to the high-water discharge during both rainy and dry seasons.

Conclusion: Results from fly dissection (Microscopy), real-time PCR and LAMP revealed the same trends pre- and post-MDA. The infection rate with animal Onchocerca sp was exceptionally low. The dense river system generate important breeding sites that govern the abundance of Simulium during both dry and rainy seasons.
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http://dx.doi.org/10.1371/journal.pntd.0008926DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7815102PMC
January 2021

Microfilariae Trigger Eosinophil Extracellular DNA Traps in a Dectin-1-Dependent Manner.

Cell Rep 2021 01;34(2):108621

Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn 53127, Germany; German Center for Infection Research (DZIF), partner site Bonn-Cologne, Bonn, Germany. Electronic address:

Eosinophils mediate protection against filarial nematodes. Our results demonstrate that eosinophil extracellular traps (EETosis) are induced by microfilariae and infective L3 larvae of Litomosoides sigmodontis. These extracellular DNA traps inhibit microfilariae motility in a DNA- and contact-dependent manner in vitro. Accordingly, microfilariae-injection triggers DNA release in an eosinophil-dependent manner in vivo and microfilariae covered with DNA traps are cleared more rapidly. Using dectin-1, we identify the required receptor for the microfilariae-induced EETosis, whereas signaling via other C-type lectin receptors, prior priming of eosinophils, and presence of antibodies are not required. The DNA released upon microfilariae-induced EETosis is mainly of mitochondrial origin, but acetylated and citrullinated histones are found within the traps. We further demonstrate that the presented DNA-dependent inhibition of microfilariae motility by eosinophils represents a conserved mechanism, as microfilariae from L. sigmodontis and the canine heartworm Dirofilaria immitis induce ETosis in murine and human eosinophils.
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http://dx.doi.org/10.1016/j.celrep.2020.108621DOI Listing
January 2021

Validation of loop-mediated isothermal amplification for the detection of Loa loa infection in Chrysops spp in experimental and natural field conditions.

Parasit Vectors 2021 Jan 6;14(1):19. Epub 2021 Jan 6.

Parasites and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, P.O. Box 63, Buea, Cameroon.

Background: The mass drug administration of ivermectin for onchocerciasis control has contributed to a significant drop in Loa loa microfilaria loads in humans that has, in turn, led to reduction of infection levels in Chrysops vectors. Accurate parasite detection is essential for assessing loiasis transmission as it provides a potential alternative or indirect strategy for addressing the problem of co-endemic loiasis and lymphatic filariasis through the Onchocerciasis Elimination Programme and it further reflects the true magnitude of the loiasis problem as excess human mortality has been reported to be associated with the disease. Although microscopy is the gold standard for detecting the infection, the sensitivity of this method is compromised when the intensity of infection is low. The loop-mediated isothermal amplification (LAMP) assay of parasite DNA is an alternative method for detecting infection which offers operational simplicity, rapidity and versatility of visual readout options. The aim of this study was to validate the Loa loa LAMP assay for the detection of infected Chrysops spp. under experimental and natural field conditions.

Methods: Two sets of 18 flies were fed on volunteers with either a low (< 10 mf/ml) or high (> 30,000mf/ml) microfilarial load. The fed flies were maintained under laboratory conditions for 14 days and then analysed using LAMP for the detection of L. loa infection. In addition, a total of 9270 flies were collected from the north-west, east, and south-west regions (SW 1 and 2) of Cameroon using sweep nets and subjected to microscopy (7841 flies) and LAMP (1291 flies plus 138 nulliparous flies) analyses.

Results: The LAMP assay successfully detected parasites in Chrysops fed on volunteers with both low and high microfilariaemic loads. Field validation and surveillance studies revealed LAMP-based infection rates ranging from 0.5 to 31.6%, with the lowest levels in SW 2 and the highest infection rates in SW 1. The LAMP assay detected significantly higher infection rates than microscopy in four of the five study sites.

Conclusion: This study demonstrated the potential of LAMP as a simple surveillance tool. It was found to be more sensitive than microscopy for the detection of experimental and natural L. loa infections in Chrysops vectors.
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http://dx.doi.org/10.1186/s13071-020-04506-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7788981PMC
January 2021

Corallopyronin A for short-course anti-wolbachial, macrofilaricidal treatment of filarial infections.

PLoS Negl Trop Dis 2020 12 7;14(12):e0008930. Epub 2020 Dec 7.

Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany.

Current efforts to eliminate the neglected tropical diseases onchocerciasis and lymphatic filariasis, caused by the filarial nematodes Onchocerca volvulus and Wuchereria bancrofti or Brugia spp., respectively, are hampered by lack of a short-course macrofilaricidal-adult-worm killing-treatment. Anti-wolbachial antibiotics, e.g. doxycycline, target the essential Wolbachia endosymbionts of filariae and are a safe prototype adult-worm-sterilizing and macrofilaricidal regimen, in contrast to standard treatments with ivermectin or diethylcarbamazine, which mainly target the microfilariae. However, treatment regimens of 4-5 weeks necessary for doxycycline and contraindications limit its use. Therefore, we tested the preclinical anti-Wolbachia drug candidate Corallopyronin A (CorA) for in vivo efficacy during initial and chronic filarial infections in the Litomosoides sigmodontis rodent model. CorA treatment for 14 days beginning immediately after infection cleared >90% of Wolbachia endosymbionts from filariae and prevented development into adult worms. CorA treatment of patently infected microfilaremic gerbils for 14 days with 30 mg/kg twice a day (BID) achieved a sustained reduction of >99% of Wolbachia endosymbionts from adult filariae and microfilariae, followed by complete inhibition of filarial embryogenesis resulting in clearance of microfilariae. Combined treatment of CorA and albendazole, a drug currently co-administered during mass drug administrations and previously shown to enhance efficacy of anti-Wolbachia drugs, achieved microfilarial clearance after 7 days of treatment at a lower BID dose of 10 mg/kg CorA, a Human Equivalent Dose of 1.4 mg/kg. Importantly, this combination led to a significant reduction in the adult worm burden, which has not yet been published with other anti-Wolbachia candidates tested in this model. In summary, CorA is a preclinical candidate for filariasis, which significantly reduces treatment times required to achieve sustained Wolbachia depletion, clearance of microfilariae, and inhibition of embryogenesis. In combination with albendazole, CorA is robustly macrofilaricidal after 7 days of treatment and fulfills the Target Product Profile for a macrofilaricidal drug.
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http://dx.doi.org/10.1371/journal.pntd.0008930DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7746275PMC
December 2020

Clinical, haematological and biochemical profiling of podoconiosis lymphoedema patients prior to their involvement in a clinical trial in the Northwest Region of Cameroon.

Trans R Soc Trop Med Hyg 2020 12;114(12):954-961

Department of Microbiology and Parasitology, University of Buea, P.O. Box 63, Buea, Cameroon.

Background: Prior to carrying out clinical trials, it is important to assess the health status of the study participants to be able to interpret subsequent changes that may be related to the effects of the treatments during the follow-up of patients. This study presents the clinical, haematological and biochemical profiles of podoconiosis patients prior to their involvement in the PodoLEDoxy clinical trial.

Methods: All lower limb lymphoedema patients visiting the centre were screened and a podoconiosis diagnosis was based on clinical manifestation and detailed medical history. Patients who satisfied the eligibility criteria were enrolled in the study and their demographic data, vital signs and medical history were collected followed by biochemical and haematological examinations.

Results: Of the 222 participants enrolled in the study, 55.4% and 41.4% had either stage 3 or 2 podoconiosis as their highest stages, respectively. On physical examination, gastritis (46%) and poor vision (2.7%) were the most prevalent health issues identified. The majority of haematological and biochemical values were within the normal range except for mean platelet volume (47.7%), plateletcrit (58.1%), platelet distribution width (66.2%), mean corpuscular volume (67.6%) and red cell distribution width-standard deviation (79.3%), where >40% of the study participants had values out of the normal.

Conclusion: The clinical, haematological and biochemical profiles of the study participants were largely within the normal range except for certain haematological parameters that might be worth investigating.
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http://dx.doi.org/10.1093/trstmh/traa146DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7738657PMC
December 2020

Sulfadiazine plasma concentrations in women with pregnancy-acquired compared to ocular toxoplasmosis under pyrimethamine and sulfadiazine therapy: a case-control study.

Eur J Med Res 2020 Nov 23;25(1):59. Epub 2020 Nov 23.

Swiss Eye Institute, Berner Augenklinik am Lindenhofspital, Bremgartenstrasse 119, CH-3012, Bern, Switzerland.

Background: Dosing recommendations for the treatment of pregnancy-acquired toxoplasmosis are empirical and widely based on experimental data. There are no pharmacological data on pregnant women with acute Toxoplasma gondii infection under treatment with pyrimethamine (PY) and sulfadiazine (SA) and our study intends to tighten this gap.

Methods: In this retrospective case-control study, we included 89 pregnant women with primary Toxoplasma infection (PT) treated with PY (50 mg first dose, then 25 mg/day), SA (50 mg/kg of body weight/day), and folinic acid (10-15 mg per week). These were compared to a group of 17 women with acute ocular toxoplasmosis (OT) treated with an initial PY dose of 75 mg, thereafter 25 mg twice a day but on the same SA and folinic acid regimen. The exact interval between drug intake and blood sampling and co-medication had not been recorded. Plasma levels of PY and SA were determined 14 ± 4 days after treatment initiation using liquid chromatography-mass spectrometry and compared using the Mann-Whitney U test at a p < 0.05 level.

Results: In 23 PT patients (26%), SA levels were below 20 mg/l. Fifteen of these 23 patients (17% of all patients) in parallel presented with PY levels below 700 µg/l. Both drug concentrations differed remarkably between individuals and groups (PY: PT median 810 µg/l, 95% CI for the median [745; 917] vs. OT 1230 µg/l [780; 1890], p = 0.006; SA: PT 46.2 mg/l [39.9; 54.4] vs. OT 70.4 mg/l [52.4; 89], p = 0.015) despite an identical SA dosing scheme.

Conclusions: SA plasma concentrations were found in the median 34% lower in pregnant women with PT compared to OT patients and fell below a lower reference value of 50 mg/l in a substantial portion of PT patients. The interindividual variability of plasma concentrations in combination with systematically lower drug levels and possibly a lower compliance in pregnant women may thus account for a still not yet supportable transmission risk. Systematic drug-level testing in PT under PY/SA treatment deserves to be considered.
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http://dx.doi.org/10.1186/s40001-020-00458-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7686675PMC
November 2020

Performance of the COVID19SEROSpeed IgM/IgG Rapid Test, an Immunochromatographic Assay for the Diagnosis of SARS-CoV-2 Infection: a Multicenter European Study.

J Clin Microbiol 2021 01 21;59(2). Epub 2021 Jan 21.

Department of Biomedical and Clinical Sciences Luigi Sacco, University of Milan, Milan, Italy.

This study assessed the diagnostic performance of the new COVID19SEROSpeed IgM/IgG rapid test (BioSpeedia, a spinoff of the Pasteur Institute of Paris) for the detection of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in comparison to other commercial antibody assays through a large cross-European investigation. The clinical specificity was assessed on 215 prepandemic sera (including some from patients with viral infections or autoimmune disorders). The clinical sensitivity was evaluated on 710 sera from 564 patients whose SARS-CoV-2 infection was confirmed by quantitative reverse transcription-PCR (qRT-PCR) and whose antibody response was compared to that measured by five other commercial tests. The kinetics of the antibody response were also analyzed in seven symptomatic patients. The specificity of the test (BioS) on prepandemic specimens was 98.1% (95% confidence interval [CI], 96.2% to 99.4%). When tested on the 710 pandemic specimens, BioS showed an overall clinical sensitivity of 86.0% (95% CI, 0.83 to 0.89), with good concordance with the Euroimmun assay (overall concordance of 0.91; Cohen's kappa coefficient of 0.62). Due in part to simultaneous detection of IgM and IgG for both S1 and N proteins, BioS exhibited the highest positive percent agreement at ≥11 days post-symptom onset (PSO). In conclusion, the BioS IgM/IgG rapid test was highly specific and demonstrated a higher positive percentage of agreement than all the enzyme-linked immunosorbent assay/chemiluminescence immunoassay (ELISA/CLIA) commercial tests considered in this study. Moreover, by detecting the presence of antibodies prior to 11 days PSO in 78.2% of the patients, the BioS test increased the efficiency of the diagnosis of SARS-CoV-2 infection in the early stages of the disease.
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http://dx.doi.org/10.1128/JCM.02240-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8111158PMC
January 2021

Solubility and Stability Enhanced Oral Formulations for the Anti-Infective Corallopyronin A.

Pharmaceutics 2020 Nov 18;12(11). Epub 2020 Nov 18.

Department of Pharmaceutical Technology and Biopharmaceutics, University of Bonn, 53121 Bonn, Germany.

Novel-antibiotics are urgently needed to combat an increase in morbidity and mortality due to resistant bacteria. The preclinical candidate corallopyronin A (CorA) is a potent antibiotic against Gram-positive and some Gram-negative pathogens for which a solid oral formulation was needed for further preclinical testing of the active pharmaceutical ingredient (API). The neat API CorA is poorly water-soluble and instable at room temperature, both crucial characteristics to be addressed and overcome for use as an oral antibiotic. Therefore, amorphous solid dispersion (ASD) was chosen as formulation principle. The formulations were prepared by spray-drying, comprising the water-soluble polymers povidone and copovidone. Stability (high-performance liquid chromatography, Fourier-transform-infrared spectroscopy, differential scanning calorimetry), dissolution (biphasic dissolution), and solubility (biphasic dissolution, Pion's T3 apparatus) properties were analyzed. Pharmacokinetic evaluations after intravenous and oral administration were conducted in BALB/c mice. The results demonstrated that the ASD formulation principle is a suitable stability- and solubility-enhancing oral formulation strategy for the API CorA to be used in preclinical and clinical trials and as a potential market product.
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http://dx.doi.org/10.3390/pharmaceutics12111105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7698778PMC
November 2020

Morbidity management and surveillance of lymphatic filariasis disease and acute dermatolymphangioadenitis attacks using a mobile phone-based tool by community health volunteers in Ghana.

PLoS Negl Trop Dis 2020 11 12;14(11):e0008839. Epub 2020 Nov 12.

Kumasi Centre for Collaborative Research in Tropical Medicine (KCCR), Kumasi, Ghana.

Morbidity burden of lymphatic filariasis (LF) relies on the information from the Mass Drug Administration (MDA) programme where Community Health Volunteers (CHVs) passively report cases identified. Consequently, the exact prevalence of morbidity cases is not always accurate. The use of mobile phone technology to report morbidity cases was piloted in Ghana using a text-based short messaging service (SMS) tool by CHVs. Though successful, illiterate CHVs could not effectively use the SMS tool. The aim of this study was to evaluate the use of a mobile phone-based Interactive Voice Response System (mIVRS) by CHVs in reporting LF morbidity cases and acute dermatolymphangioadenitis (ADLA) attacks in Ghana. The mIVRS was designed as a surveillance tool to capture LF data in Kassena Nankana Districts of Ghana. One hundred CHVs were trained to identify and report lymphedema and hydrocele cases as well as ADLA attacks by calling a hotline linked to the mIVRS. The system asked a series of questions about the disease condition. The ability of the CHV to report accurately was assessed and the data from the mIVRS were compared with the paper records from the CHVs and existing MDA programme records from the same communities and period. Higher numbers of lymphedema and hydrocele cases were recorded by the CHVs using the mIVRS (n = 590 and n = 103) compared to the paper-based reporting (n = 417 and n = 76) and the MDA records (n = 154 and n = 84). Female CHVs, CHVs above 40 years, and CHVs with higher educational levels were better at paper-based reporting (P = 0.007, P = 0.001, P = 0.049 respectively). The system, when fully developed and linked to national databases, may help to overcome underreporting of morbidity cases and ADLA attacks in endemic communities. The system has the potential to be further expanded to other diseases.
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http://dx.doi.org/10.1371/journal.pntd.0008839DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7685506PMC
November 2020

Differential susceptibility of Onchocerca volvulus microfilaria to ivermectin in two areas of contrasting history of mass drug administration in Cameroon: relevance of microscopy and molecular techniques for the monitoring of skin microfilarial repopulation within six months of direct observed treatment.

BMC Infect Dis 2020 Oct 2;20(1):726. Epub 2020 Oct 2.

Parasites and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, P.O. Box 63, Buea, Cameroon.

Background: Ivermectin is an excellent microfilaricide against Onchocerca volvulus. However, in some regions, long term use of ivermectin has resulted in sub-optimal responses to the treatment. More data to properly document the phenomenon in various contexts of ivermectin mass drug administration (IVM-MDA) is needed. Also, there is a need to accurately monitor a possible repopulation of skin by microfilariae following treatment. Skin snip microscopy is known to have a low sensitivity in individuals with light infections, which can be the case following treatment. This study was designed with two complementary objectives: (i) to assess the susceptibility of O. volvulus microfilariae to ivermectin in two areas undergoing IVM-MDA for different lengths of time, and (ii) to document the repopulation of skin by the O. volvulus microfilariae following treatment, using 3 independent diagnostic techniques.

Method: Identified microfilaridermic individuals were treated with ivermectin and re-examined after 1, 3, and 6 months using microscopy, actin real-time PCR (actin-qPCR) and O-150 LAMP assays. Susceptibility to ivermectin and trends in detecting reappearance of skin microfilariae were determined using three techniques. Microscopy was used as an imperfect gold standard to determine the performance of actin-qPCR and LAMP.

Results: In Bafia with over 20 years of IVM-MDA, 11/51 (21.6%) direct observe treated microfilaridemic participants were still positive for skin microfilariae after 1 month. In Melong, with 10 years of IVM-MDA, 2/29 (6.9%) treated participants were still positive. The microfilarial density reduction per skin biopsy within one month following treatment was significantly lower in participants from Bafia. In both study sites, the molecular techniques detected higher proportions of infected individuals than microscopy at all monitoring time points. LAMP demonstrated the highest levels of sensitivity and real-time PCR was found to have the highest specificity.

Conclusion: Patterns in skin mirofilariae clearance and repopulation were established. O. volvulus worms from Bafia with higher number of annual MDA displayed a lower clearance and higher repopulation rate after treatment with ivermectin. Molecular assays displayed higher sensitivity in monitoring O. volvulus microfilaridemia within six months following treatment.
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http://dx.doi.org/10.1186/s12879-020-05444-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7530974PMC
October 2020

Generation of Loa loa infective larvae by experimental infection of the vector, Chrysops silacea.

PLoS Negl Trop Dis 2020 08 17;14(8):e0008415. Epub 2020 Aug 17.

Parasites and Vector Biology research unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon.

Basic and translational research on loiasis, a filarial nematode infection of medical importance, is impeded by a lack of suitable Loa loa infection models and techniques of obtaining and culturing life cycle stages. We describe the development of a new method for routine production of infective third-stage larvae (L3) of L. loa from the natural intermediate arthropod vector host, Chrysops silacea, following experimental infection with purified microfilariae. At 14-days post-infection of C. silacea, the fly survival rate was 43%. Survival was significantly higher in flies injected with 50 mf (55.2%) than those that received 100 mf (31.0%). However, yield per surviving fly and total yield of L3 was markedly higher in the group of flies inoculated with 100 mf (3474 vs 2462 L3 produced). The abdominal segment hosted the highest percentage recovery of L3 (47.7%) followed by head (34.5%) and thorax (17.9%). L. loa larval survival was higher than 90% after 30 days of in vitro culture. The in vitro moulting success rate to the L4 larval stage was 59.1%. After experimental infection of RAG2-/-IL-2γc-/-mice, the average L. loa juvenile adult worm recovery rate was 10.5% at 62 dpi. More than 87% of the worms were recovered from the muscles and subcutaneous tissues. Worms recovered measured an average 24.3 mm and 11.4 mm in length for females (n = 5) and males (n = 5), respectively. In conclusion, L. loa mf injected into C. silacea intrathoracically develop into infective larvae that remain viable and infective comparable to L3 obtained through natural feeding on the human host. This technique further advances the development of a full laboratory life cycle of L. loa where mf derived from experimentally-infected animals may be utilized to passage life cycle generations via intrathoracic injections of wild-caught vector hosts.
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http://dx.doi.org/10.1371/journal.pntd.0008415DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7470323PMC
August 2020

Complete Mitochondrial Genome Sequence of .

Microbiol Resour Announc 2020 Jul 23;9(30). Epub 2020 Jul 23.

Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA

The 13,647-bp complete mitochondrial genome of was sequenced and is syntenic to the mitochondrial genome of Phylogenetic analysis of the mitochondrial genome is consistent with the known phylogeny of ONC5 group filarial nematodes.
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http://dx.doi.org/10.1128/MRA.00490-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7378030PMC
July 2020

Ethnobotanical survey, anthelmintic effects and cytotoxicity of plants used for treatment of helminthiasis in the Central and Kara regions of Togo.

BMC Complement Med Ther 2020 Jul 7;20(1):212. Epub 2020 Jul 7.

Ecole Supérieure des Techniques Biologiques et Alimentaires (ESTBA)/Laboratoire de Microbiologie et de Contrôle de Qualité des Denrées Alimentaires/Unité de Recherche en Immunologie et Immunomodulation (UR2IM), Université de Lomé, 01 BP 1515, Lomé, Togo.

Background: Traditional medicines are the main source of treatment of helminthiasis in endemic areas of Togo. The present study aimed to investigate the plants used by Traditional healers (THs) to treat helminth infections in endemic communities within the Central and Kara regions of Togo and to evaluate the anthelmintic activity of the three most cited plants.

Methods: An ethnobotanical survey was conducted from 19 to 24 June 2017 among traditional healers in the Central and Kara regions of Togo. The anthelmintic activity of the most cited plants namely Aframomum melegueta K. Schum, Khaya senegalensis A. Juss and Xylopia aethiopica A. Rich, was evaluated using microfilariae (Mf) of Litomosoides sigmodontis. The plants were evaluated for cytotoxicity according to the recommendation of NF EN ISO 10993-5 standard using the propidium iodide (PI) dye by flow cytometry on human peripheral blood mononuclear cells.

Results: A total of 197 THs were interviewed and 41 plant species were recorded. Leguminosae (14.6%) and Annonaceae (9.7%) families constitute the highest number of species cited for treatment of helminth infections. Afromomum melegueta was the most cited by the THs for the treatment of onchocerciasis (UV = 0.036) while X. aethiopica was associated with the treatment of schistosomiasis (UV = 0.061) and lymphatic filariasis (UV = 0.061). There was a great agreement among the THs regarding ethnomedicinal uses of plants to treat helminthiasis with ICF values ranging from 0.57 to 0.67. The anthelmintic assay yielded lethal doses values of 233 μg/mL, 265 μg/mL and 550 μg/mL, respectively for X. aethiopica, A. melegueta and K. senegalensis. Afromomum melegueta and X. aethiopica presented no cytotoxicity, less than 20% death, whereas K. senegalensis induced moderate toxicity, 24 ± 8% death.

Conclusion: This study demonstrated the scientific rationale for the use of plants to treat helminthiasis in the Togolese traditional medicine. However, the use of K. senegalensis requires more caution since the plant is fairly toxic.

Trial Registration: NA.
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http://dx.doi.org/10.1186/s12906-020-03008-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7341664PMC
July 2020

Oxfendazole mediates macrofilaricidal efficacy against the filarial nematode Litomosoides sigmodontis in vivo and inhibits Onchocerca spec. motility in vitro.

PLoS Negl Trop Dis 2020 07 6;14(7):e0008427. Epub 2020 Jul 6.

Drugs for Neglected Diseases initiative, Geneva, Switzerland.

A major impediment to eliminate lymphatic filariasis and onchocerciasis is the lack of effective short-course macrofilaricidal drugs or regimens that are proven to be safe for both infections. In this study we tested oxfendazole, an anthelmintic shown to be well tolerated in phase 1 clinical trials. In vitro, oxfendazole exhibited modest to marginal motility inhibition of adult worms of Onchocerca gutturosa, pre-adult worms of Onchocerca volvulus and Onchocerca lienalis microfilariae. In vivo, five days of oral treatments provided sterile cure with up to 100% macrofilaricidal efficacy in the murine Litomosoides sigmodontis model of filariasis. In addition, 10 days of oral treatments with oxfendazole inhibited filarial embryogenesis in patent L. sigmodontis-infected jirds and subsequently led to a protracted but complete clearance of microfilaremia. The macrofilaricidal effect observed in vivo was selective, as treatment with oxfendazole of microfilariae-injected naïve mice was ineffective. Based on pharmacokinetic analysis, the driver of efficacy is the maintenance of a minimal efficacious concentration of approximately 100 ng/ml (based on subcutaneous treatment at 25 mg/kg in mice). From animal models, the human efficacious dose is predicted to range from 1.5 to 4.1 mg/kg. Such a dose has already been proven to be safe in phase 1 clinical trials. Oxfendazole therefore has potential to be efficacious for treatment of human filariasis without causing adverse reactions due to drug-induced microfilariae killing.
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http://dx.doi.org/10.1371/journal.pntd.0008427DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7365463PMC
July 2020

Macrophages Mediate Increased CD8 T Cell Inflammation During Weight Loss in Formerly Obese Mice.

Front Endocrinol (Lausanne) 2020 28;11:257. Epub 2020 Apr 28.

Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany.

Even after successful weight reduction, obese adults tend to quickly regain the lost weight. This raises the question of whether weight loss improves the underlying chronic adipose tissue inflammation characteristic of obesity. In order to improve our understanding of the mechanisms that reshape metabolic organs during weight loss, we investigated the macrophage and T cell function of the liver and adipose tissue on reversing high fat diet (HFD) mice to normal control diet (NCD). Obese mice that were switched to NCD showed an improvement in their metabolic profile that included enhanced glucose and insulin tolerance, decreased cholesterol, triglyceride, serum glutamic-oxaloacetic transaminase (SGOT), and serum glutamic pyruvic transaminase (SGPT) levels that were comparable to NCD controls. However, despite weight loss, increased frequencies, but not total numbers, of IL-17+ and IL-22+ CD4+ T cells, IFN-γ+ and TNF+ CD8+ T cells and IL-17+ and IL-22+ CD8+ T cells were observed in the adipose tissue of mice switched from HFD to NCD compared to NCD and even HFD fed mice. Further, in the liver, IFN-γ+ and TNF+ CD8+ T cell, IL-17+ and IL-22+ CD8+ T cell, macrophage frequencies and their expression of antigen presenting molecules were increased. To determine if macrophages are the major determinants of the sustained inflammation observed during weight loss, we depleted macrophages, which significantly reduced IFN-γ+, TNF+, IL-17+, and IL-22+ CD8+ T cell frequencies in the liver and the adipose tissue. In conclusion, we show that although weight loss improves the metabolic profile, there is an active and ongoing CD8+ T cell inflammation in liver and adipose tissue mediated by macrophages.
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http://dx.doi.org/10.3389/fendo.2020.00257DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7198814PMC
May 2021

Immune Sensing of Synthetic, Bacterial, and Protozoan RNA by Toll-like Receptor 8 Requires Coordinated Processing by RNase T2 and RNase 2.

Immunity 2020 04;52(4):591-605.e6

Department of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany. Electronic address:

Human toll-like receptor 8 (TLR8) activation induces a potent T helper-1 (Th1) cell response critical for defense against intracellular pathogens, including protozoa. The receptor harbors two distinct binding sites, uridine and di- and/or trinucleotides, but the RNases upstream of TLR8 remain poorly characterized. We identified two endolysosomal endoribonucleases, RNase T2 and RNase 2, that act synergistically to release uridine from oligoribonucleotides. RNase T2 cleaves preferentially before, and RNase 2 after, uridines. Live bacteria, P. falciparum-infected red blood cells, purified pathogen RNA, and synthetic oligoribonucleotides all required RNase 2 and T2 processing to activate TLR8. Uridine supplementation restored RNA recognition in RNASE2 or RNASET2 but not RNASE2RNASET2 cells. Primary immune cells from RNase T2-hypomorphic patients lacked a response to bacterial RNA but responded robustly to small-molecule TLR8 ligands. Our data identify an essential function of RNase T2 and RNase 2 upstream of TLR8 and provide insight into TLR8 activation.
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http://dx.doi.org/10.1016/j.immuni.2020.03.009DOI Listing
April 2020

The design and development of a multicentric protocol to investigate the impact of adjunctive doxycycline on the management of peripheral lymphoedema caused by lymphatic filariasis and podoconiosis.

Parasit Vectors 2020 Mar 30;13(1):155. Epub 2020 Mar 30.

Institute for Medical Microbiology, Immunology and Parasitology (IMMIP), German Centre for Infection Research (DZIF), Bonn-Cologne Site, University Hospital Bonn, Venusberg-Campus 1, 53105, Bonn, Germany.

Background: As new lymphatic filariasis infections are eliminated through mass chemotherapy, previously affected individuals are left with the sequellae, especially chronic progressive lymphoedema. Currently this is managed by careful attention to limb hygiene to prevent infection. Studies over the past 15 years have suggested that the incorporation of doxycycline treatment may arrest or even reverse progression of lymphoedema. Most of this work has been observational or based on small studies, and if this intervention is effective, studies need to be conducted on a larger scale and under diverse geographical and social conditions before it can be incorporated into treatment policy.

Methods/design: The double-blind, placebo-controlled study was designed to investigate the impact of six weeks treatment with doxycycline added to standard limb hygiene on early stage filarial lymphoedema in five sites in Africa and the Indian subcontinent. One site in Cameroon is selected for studying lymphoedema in podoconiosis. Each site was individually powered with the potential to undertake a meta-analysis on completion. Evaluation methods followed those used in Ghana in 2012 with additions resulting from advances in technology. The details of the core protocol and how it was varied to take account of differing situations at each of the sites are provided. The study will enrol up to 1800 patients and will complete in mid-2021.

Conclusions: This paper provides details of what challenges were faced during its development and discusses the issues and how they were resolved. In particular, the reasons for inclusion of new technology and the problems encountered with the supply of drugs for the studies are described in detail. By making these details available, it is hoped that the study protocol will help others interested in improving treatment for filarial lymphoedema in the design of future studies. Trial registration India: Clintrials.gov. NCT02929121 registered 10 Oct 2016: https://clinicaltrials.gov/ct2/show/NCT02929121 Mali: Clintrials.gov. NCT02927496 registered 7 Oct 2016: https://clinicaltrials.gov/ct2/show/NCT0292749 Sri Lanka: Clintrials.gov. NCT02929134 registered 10 Oct 2016: https://clinicaltrials.gov/ct2/show/NCT02929134 Ghana: ISRCTN. 14042737 registered 10 July 2017: https://doi.org/10.1186/ISRCTN14042737 Tanzania: ISRCTN. 65756724 registered 21 July 2017: https://doi.org/10.1186/ISRCTN65756724 Cameroon: ISRCTN. 1181662 registered 25 July 2017: https://doi.org/10.1186/ISRCTN11881662.
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http://dx.doi.org/10.1186/s13071-020-04024-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7106687PMC
March 2020

S100A8/S100A9 deficiency increases neutrophil activation and protective immune responses against invading infective L3 larvae of the filarial nematode Litomosoides sigmodontis.

PLoS Negl Trop Dis 2020 02 27;14(2):e0008119. Epub 2020 Feb 27.

Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany.

Neutrophils are essentially involved in protective immune responses against invading infective larvae of filarial nematodes. The present study investigated the impact of S100A8/S100A9 on protective immune responses against the rodent filarial nematode Litomosoides sigmodontis. S100A9 forms with S100A8 the heterodimer calprotectin, which is expressed by circulating neutrophils and monocytes and mitigates or amplifies tissue damage as well as inflammation depending on the immune environment. Mice deficient for S100A8/A9 had a significantly reduced worm burden in comparison to wildtype (WT) animals 12 days after infection (dpi) with infective L3 larvae, either by the vector or subcutaneous inoculation, the latter suggesting that circumventing natural immune responses within the epidermis and dermis do not alter the phenotype. Nevertheless, upon intradermal injection of L3 larvae, increased total numbers of neutrophils, eosinophils and macrophages were observed within the skin of S100A8/A9-/- mice. Furthermore, upon infection the bronchoalveolar and thoracic cavity lavage of S100A8/A9-/- mice showed increased concentrations of CXCL-1, CXCL-2, CXCL-5, as well as elastase in comparison to the WT controls. Neutrophils from S100A8/A9-/- mice exhibited an increased in vitro activation and reduced L3 larval motility more effectively in vitro compared to WT neutrophils. The depletion of neutrophils from S100A8/A9-/- mice prior to L. sigmodontis infection until 5dpi abrogated the protective effect and led to an increased worm burden, indicating that neutrophils mediate enhanced protective immune responses against invading L3 larvae in S100A8/A9-/- mice. Interestingly, complete circumvention of protective immune responses in the skin and the lymphatics by intravenous injection of L3 larvae reversed the phenotype and resulted in an increased worm burden in S100A8/A9-/- mice. In summary, our results reveal that lack of S100A8/S100A9 triggers L3-induced inflammatory responses, increasing chemokine levels, granulocyte recruitment as well as neutrophil activation and therefore impairs larval migration and susceptibility for filarial infection.
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http://dx.doi.org/10.1371/journal.pntd.0008119DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064255PMC
February 2020

Comparison of immune responses to Loa loa stage-specific antigen extracts in Loa loa-exposed BALB/c mice upon clearance of infection.

Parasit Vectors 2020 Feb 7;13(1):51. Epub 2020 Feb 7.

Parasite and Vector Biology Research Unit, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon.

Background: Different immune mechanisms are capable of killing developmental stages of filarial nematodes and these mechanisms are also likely to vary between the primary and a challenge infection. However, the lack of a detailed analysis of cytokine, chemokine and immunoglobulin levels in human loiasis is still evident. Therefore, detailed analysis of immune responses induced by the different developmental stages of Loa loa in immune-competent BALB/c mice will aid in the characterization of distinct immune responses that are important for the immunity against loiasis.

Methods: Different developmental stages of L. loa were obtained from human peripheral blood (microfilariae, MF), the transmitting vector, Chrysops (larval stage 3, L3) and infected immune-deficient BALB/cRAG2γc mice (L4, L5, adult worms). Groups of wildtype BALB/c mice were then injected with the isolated stages and after 42 days post-infection (pi), systemic cytokine, chemokine and immunoglobulin levels were determined. These were then compared to L. loa-specific responses from in vitro re-stimulated splenocytes from individual mice. All parameters were determined using Luminex technology.

Results: In a pilot study, BALB/c mice cleared the different life stages of L. loa within 42 days pi and systemic cytokine, chemokine and immunoglobulin levels were equal between infected and naive mice. Nevertheless, L. loa-specific re-stimulation of splenocytes from mice infected with L5, MF or adult worms led to induction of Th2, Th17 and chemokine secretion patterns.

Conclusions: This study shows that although host immunity remains comparable to naive mice, clearance of L. loa life-cycle development stages can induce immune cell memory leading to cytokine, chemokine and immunoglobulins secretion patterns which might contribute to immunity and protection against reinfection.
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http://dx.doi.org/10.1186/s13071-020-3921-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7006431PMC
February 2020

In vivo efficacy of the boron-pleuromutilin AN11251 against Wolbachia of the rodent filarial nematode Litomosoides sigmodontis.

PLoS Negl Trop Dis 2020 01 27;14(1):e0007957. Epub 2020 Jan 27.

Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany.

The elimination of filarial diseases such as onchocerciasis and lymphatic filariasis is hampered by the lack of a macrofilaricidal-adult worm killing-drug. In the present study, we tested the in vivo efficacy of AN11251, a boron-pleuromutilin that targets endosymbiotic Wolbachia bacteria from filarial nematodes and compared its efficacy to doxycycline and rifampicin. Doxycycline and rifampicin were previously shown to deplete Wolbachia endosymbionts leading to a permanent sterilization of the female adult filariae and adult worm death in human clinical studies. Twice-daily oral treatment of Litomosoides sigmodontis-infected mice with 200 mg/kg AN11251 for 10 days achieved a Wolbachia depletion > 99.9% in the adult worms, exceeding the Wolbachia reduction by 10-day treatments with bioequivalent human doses of doxycycline and a similar reduction as high-dose rifampicin (35 mg/kg). Wolbachia reductions of > 99% were also accomplished by 14 days of oral AN11251 at a lower twice-daily dose (50 mg/kg) or once-per-day 200 mg/kg AN11251 treatments. The combinations tested of AN11251 with doxycycline had no clear beneficial impact on Wolbachia depletion, achieving a > 97% Wolbachia reduction with 7 days of treatment. These results indicate that AN11251 is superior to doxycycline and comparable to high-dose rifampicin in the L. sigmodontis mouse model, allowing treatment regimens as short as 10-14 days. Therefore, AN11251 represents a promising pre-clinical candidate that was identified in the L. sigmodontis model, and could be further evaluated and developed as potential clinical candidate for human lymphatic filariasis and onchocerciasis.
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http://dx.doi.org/10.1371/journal.pntd.0007957DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7004383PMC
January 2020

Dataset on maintenance of microfilariae and drug testing.

Data Brief 2020 Feb 4;28:104930. Epub 2019 Dec 4.

Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.

Endemic communities of infections have been neglected since associated pathology remains undefined. Consequently, improvements in drug therapy have also been ignored despite a large number of infected individuals in areas of Cameroon. Thus, we established an system to culture microfilariae (Mf); the transmission stage of infection. In short, we compared the ability of two renowned culture media (Dulbecco's Modified Eagle's Medium (DMEM) and Roswell Park Memorial Institute (RPMI-1640)) to sustain Mf in culture. Media were supplemented with 10% fetal bovine serum (FBS) and monkey kidney epithelial cells (LLC-MK) were used as feeder cells. As readout we assessed Mf survival and motility using a standardised microscopy assessment strategy. Moreover, this culture system was used to test susceptibility levels of microfilariae to different chemotherapeutic agents. Parasite motility was scored daily using a graded system and analysed using the average motility and area under the motility curve of Mf. These datasets were analysed and discussed in detail in the related article entitled: " maintenance of microfilariae and its relevance for drug screening" [1].
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http://dx.doi.org/10.1016/j.dib.2019.104930DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6920388PMC
February 2020

Macrofilaricidal Benzimidazole-Benzoxaborole Hybrids as an Approach to the Treatment of River Blindness: Part 1. Amide Linked Analogs.

ACS Infect Dis 2020 02 14;6(2):173-179. Epub 2020 Jan 14.

Anacor Pharmaceuticals, Inc. , 1020 E. Meadow Circle , Palo Alto , California 94303 , United States.

A series of benzimidazole-benzoxaborole hybrid molecules linked via an amide linker are described that exhibit good activity against , a filarial nematode responsible for the disease onchocerciasis, also known as river blindness. The lead identified in this series,  (AN8799), was found to have acceptable pharmacokinetic properties to enable evaluation in animal models of human filariasis. Compound was effective in killing , , and worms present in Mongolian gerbils when dosed subcutaneously as a suspension at 100 mg/kg/day for 14 days but not when dosed orally at 100 mg/kg/day for 28 days. The measurement of plasma levels of at the end of the dosing period and at the time of sacrifice revealed an interesting dependence of activity on the extended exposure for both and the positive control, flubendazole.
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http://dx.doi.org/10.1021/acsinfecdis.9b00396DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7026885PMC
February 2020

Short-course quinazoline drug treatments are effective in the Litomosoides sigmodontis and Brugia pahangi jird models.

Int J Parasitol Drugs Drug Resist 2020 04 10;12:18-27. Epub 2019 Dec 10.

Dept. of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, USA.

The quinazolines CBR417 and CBR490 were previously shown to be potent anti-wolbachials that deplete Wolbachia endosymbionts of filarial nematodes and present promising pre-clinical candidates for human filarial diseases such as onchocerciasis. In the present study we tested both candidates in two models of chronic filarial infection, namely the Litomosoides sigmodontis and Brugia pahangi jird model and assessed their long-term effect on Wolbachia depletion, microfilariae counts and filarial embryogenesis 16-18 weeks after treatment initiation (wpt). Once per day (QD) oral treatment with CBR417 (50 mg/kg) for 4 days or twice per day (BID) with CBR490 (25 mg/kg) for 7 days during patent L. sigmodontis infection reduced the Wolbachia load by >99% and completely cleared peripheral microfilaremia from 10-14 wpt. Similarly, 7 days of QD treatments (40 mg/kg) with CBR417 or CBR490 cleared >99% of Wolbachia from B. pahangi and reduced peritoneal microfilariae counts by 93% in the case of CBR417 treatment. Transmission electron microscopy analysis indicated intensive damage to the B. pahangi ovaries following CBR417 treatment and in accordance filarial embryogenesis was inhibited in both models after CBR417 or CBR490 treatment. Suboptimal treatment regimens of CBR417 or CBR490 did not lead to a maintained reduction of the microfilariae and Wolbachia load. In conclusion, CBR417 or CBR490 are pre-clinical candidates for filarial diseases, which achieve long-term clearance of Wolbachia endosymbionts of filarial nematodes, inhibit filarial embryogenesis and clear microfilaremia with treatments as short as 7 days.
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http://dx.doi.org/10.1016/j.ijpddr.2019.12.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6931063PMC
April 2020