Publications by authors named "Sara Lustigman"

118 Publications

Development of a recombinant vaccine against human onchocerciasis.

Expert Rev Vaccines 2021 Sep 17:1-12. Epub 2021 Sep 17.

Laboratory of Molecular Parasitology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, NY, USA.

Introduction: Human onchocerciasis caused by the filarial nematode parasite remains a major cause of debilitating disease infecting millions primarily in Sub-Saharan Africa. The development of a prophylactic vaccine, along with mass drug administration, would facilitate meeting the goal of onchocerciasis elimination by 2030.

Areas Covered: Models used to study immunity to include natural infection of cattle with and infective third-stage larvae implanted within diffusion chambers in mice. A vaccine, comprised of two adjuvanted recombinant antigens, induced protective immunity in genetically diverse mice suggesting that it will function similarly in diverse human populations. These antigens were recognized by immune humans and also induced protective immunity against . We describe the development of a fusion protein composed of the two vaccine antigens with the plan to test the vaccine in cows and non-human primates as a prelude to the initiation of phase 1 clinical trials.

Expert Opinion: The adjuvanted vaccine composed of two antigens -103 and -RAL-2 was shown to be consistently effective at inducing protective immunity using multiple immune mechanisms. The vaccine is ready for further evaluation in other animal models before moving to clinical trials in humans.
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http://dx.doi.org/10.1080/14760584.2021.1977125DOI Listing
September 2021

Drugs that target early stages of Onchocerca volvulus: A revisited means to facilitate the elimination goals for onchocerciasis.

PLoS Negl Trop Dis 2021 02 18;15(2):e0009064. Epub 2021 Feb 18.

Molecular Parasitology, Lindsey F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America.

Several issues have been identified with the current programs for the elimination of onchocerciasis that target only transmission by using mass drug administration (MDA) of the drug ivermectin. Alternative and/or complementary treatment regimens as part of a more comprehensive strategy to eliminate onchocerciasis are needed. We posit that the addition of "prophylactic" drugs or therapeutic drugs that can be utilized in a prophylactic strategy to the toolbox of present microfilaricidal drugs and/or future macrofilaricidal treatment regimens will not only improve the chances of meeting the elimination goals but may hasten the time to elimination and also will support achieving a sustained elimination of onchocerciasis. These "prophylactic" drugs will target the infective third- (L3) and fourth-stage (L4) larvae of Onchocerca volvulus and consequently prevent the establishment of new infections not only in uninfected individuals but also in already infected individuals and thus reduce the overall adult worm burden and transmission. Importantly, an effective prophylactic treatment regimen can utilize drugs that are already part of the onchocerciasis elimination program (ivermectin), those being considered for MDA (moxidectin), and/or the potential macrofilaricidal drugs (oxfendazole and emodepside) currently under clinical development. Prophylaxis of onchocerciasis is not a new concept. We present new data showing that these drugs can inhibit L3 molting and/or inhibit motility of L4 at IC50 and IC90 that are covered by the concentration of these drugs in plasma based on the corresponding pharmacological profiles obtained in human clinical trials when these drugs were tested using various doses for the therapeutic treatments of various helminth infections.
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http://dx.doi.org/10.1371/journal.pntd.0009064DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7891776PMC
February 2021

Onchocerca volvulus bivalent subunit vaccine induces protective immunity in genetically diverse collaborative cross recombinant inbred intercross mice.

NPJ Vaccines 2021 Jan 26;6(1):17. Epub 2021 Jan 26.

Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.

This study tests the hypothesis that an Onchocerca volvulus vaccine, consisting of two recombinant antigens (Ov-103 and Ov-RAL-2) formulated with the combination-adjuvant Advax-2, can induce protective immunity in genetically diverse Collaborative Cross recombinant inbred intercross mice (CC-RIX). CC-RIX lines were immunized with the O. volvulus vaccine and challenged with third-stage larvae. Equal and significant reductions in parasite survival were observed in 7 of 8 CC-RIX lines. Innate protective immunity was seen in the single CC-RIX line that did not demonstrate protective adaptive immunity. Analysis of a wide array of immune factors showed that each line of mice have a unique set of immune responses to vaccination and challenge suggesting that the vaccine is polyfunctional, inducing different equally-protective sets of immune responses based on the genetic background of the immunized host. Vaccine efficacy in genetically diverse mice suggests that it will also be effective in genetically complex human populations.
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http://dx.doi.org/10.1038/s41541-020-00276-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7838260PMC
January 2021

An Integrated Approach to Identify New Anti-Filarial Leads to Treat River Blindness, a Neglected Tropical Disease.

Pathogens 2021 Jan 14;10(1). Epub 2021 Jan 14.

Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, 4523 Clayton Ave., St. Louis, MO 63110, USA.

Filarial worms cause multiple debilitating diseases in millions of people worldwide, including river blindness. Currently available drugs reduce transmission by killing larvae (microfilariae), but there are no effective cures targeting the adult parasites (macrofilaricides) which survive and reproduce in the host for very long periods. To identify effective macrofilaricides, we carried out phenotypic screening of a library of 2121 approved drugs for clinical use against adult and prioritized the hits for further studies by integrating those results with a computational prioritization of drugs and associated targets. This resulted in the identification of 18 hits with anti-macrofilaricidal activity, of which two classes, azoles and aspartic protease inhibitors, were further expanded upon. Follow up screening against spp. (adult and pre-adult ) confirmed activity for 13 drugs (the majority having IC < 10 μM), and a counter screen of a subset against microfilariae showed the potential to identify selective drugs that prevent adverse events when co-infected individuals are treated. Stage specific activity was also observed. Many of these drugs are amenable to structural optimization, and also have known canonical targets, making them promising candidates for further optimization that can lead to identifying and characterizing novel anti-macrofilarial drugs.
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http://dx.doi.org/10.3390/pathogens10010071DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7830784PMC
January 2021

Vaccination with novel low-molecular weight proteins secreted from Trichinella spiralis inhibits establishment of infection.

PLoS Negl Trop Dis 2020 11 18;14(11):e0008842. Epub 2020 Nov 18.

School of Health, Sport and Bioscience, University of East London, London, United Kingdom.

Trichinella spiralis muscle stage larvae (mL1) produce excretory-secreted products (ESPs), a complex mixture of protein, which are believed to be important for establishing or maintaining an infection niche within skeletal muscle and the intestine. Studies of both whole ESPs and individual cloned proteins have shown that some ESPs are potent immunogens capable of eliciting protective immune responses. Here we describe two novel proteins, Secreted from Muscle stage Larvae SML-4 and SML-5 which are 15 kDa and 12 kDa respectively. The genes encoding these proteins are highly conserved within the Trichinellids, are constituents of mL1 ESP and localized in the parasite stichosome. While SML-5 is only expressed in mL1 and early stages of adult nematode development, SML-4 is a tyvosylated glycoprotein also produced by adult nematodes, indicating it may have a function in the enteral phase of the infection. Vaccination with these proteins resulted in an impaired establishment of adult stages and consequently a reduction in the burden of mL1 in BALB/c mice. This suggests that both proteins may be important for establishment of parasite infection of the intestine and are prophylactic vaccine candidates.
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http://dx.doi.org/10.1371/journal.pntd.0008842DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7673540PMC
November 2020

Preliminary evaluations of 3-dimensional human skin models for their ability to facilitate in vitro the long-term development of the debilitating obligatory human parasite Onchocerca volvulus.

PLoS Negl Trop Dis 2020 11 5;14(11):e0008503. Epub 2020 Nov 5.

Translational Center for Regenerative Therapies, Fraunhofer ISC, Würzburg, Germany.

Onchocerciasis also known as river blindness is a neglected tropical disease and the world's second-leading infectious cause of blindness in humans; it is caused by Onchocerca volvulus. Current treatment with ivermectin targets microfilariae and transmission and does not kill the adult parasites, which reside within subcutaneous nodules. To support the development of macrofilaricidal drugs that target the adult worm to further support the elimination of onchocerciasis, an in-depth understanding of O. volvulus biology especially the factors that support the longevity of these worms in the human host (>10 years) is required. However, research is hampered by a lack of access to adult worms. O. volvulus is an obligatory human parasite and no small animal models that can propagate this parasite were successfully developed. The current optimized 2-dimensional (2-D) in vitro culturing method starting with O. volvulus infective larvae does not yet support the development of mature adult worms. To overcome these limitations, we have developed and applied 3-dimensional (3-D) culture systems with O. volvulus larvae that simulate the human in vivo niche using in vitro engineered skin and adipose tissue. Our proof of concept studies have shown that an optimized indirect co-culture of in vitro skin tissue supported a significant increase in growth of the fourth-stage larvae to the pre-adult stage with a median length of 816-831 μm as compared to 767 μm of 2-D cultured larvae. Notably, when larvae were co-cultured directly with adipose tissue models, a significant improvement for larval motility and thus fitness was observed; 95% compared to 26% in the 2-D system. These promising co-culture concepts are a first step to further optimize the culturing conditions and improve the long-term development of adult worms in vitro. Ultimately, it could provide the filarial research community with a valuable source of O. volvulus worms at various developmental stages, which may accelerate innovative unsolved biomedical inquiries into the parasite's biology.
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http://dx.doi.org/10.1371/journal.pntd.0008503DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7671495PMC
November 2020

Yeast-expressed SARS-CoV recombinant receptor-binding domain (RBD219-N1) formulated with aluminum hydroxide induces protective immunity and reduces immune enhancement.

Vaccine 2020 11 22;38(47):7533-7541. Epub 2020 Sep 22.

Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, TX, USA. Electronic address:

We developed a severe acute respiratory syndrome (SARS) subunit recombinant protein vaccine candidate based on a high-yielding, yeast-engineered, receptor-binding domain (RBD219-N1) of the SARS beta-coronavirus (SARS-CoV) spike (S) protein. When formulated with Alhydrogel®, RBD219-N1 induced high levels of neutralizing antibodies against both pseudotyped virus and a clinical (mouse-adapted) isolate of SARS-CoV. Here, we report that mice immunized with RBD219-N1/Alhydrogel® were fully protected from lethal SARS-CoV challenge (0% mortality), compared to ~30% mortality in mice immunized with the SARS S protein formulated with Alhydrogel®, and 100% mortality in negative controls. An RBD219-N1 formulation with Alhydrogel® was also superior to the S protein, unadjuvanted RBD, and AddaVax (MF59-like adjuvant)-formulated RBD in inducing specific antibodies and preventing cellular infiltrates in the lungs upon SARS-CoV challenge. Specifically, a formulation with a 1:25 ratio of RBD219-N1 to Alhydrogel® provided high neutralizing antibody titers, 100% protection with non-detectable viral loads with minimal or no eosinophilic pulmonary infiltrates. As a result, this vaccine formulation is under consideration for further development against SARS-CoV and potentially other emerging and re-emerging beta-CoVs such as SARS-CoV-2.
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http://dx.doi.org/10.1016/j.vaccine.2020.09.061DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7508514PMC
November 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

Prediction pipeline for discovery of regulatory motifs associated with Brugia malayi molting.

PLoS Negl Trop Dis 2020 06 23;14(6):e0008275. Epub 2020 Jun 23.

Department of Biology, Center for Genomics and Systems Biology, New York University, New York, New York, United States of America.

Filarial nematodes can cause debilitating diseases in humans. They have complicated life cycles involving an insect vector and mammalian hosts, and they go through a number of developmental molts. While whole genome sequences of parasitic worms are now available, very little is known about transcription factor (TF) binding sites and their cognate transcription factors that play a role in regulating development. To address this gap, we developed a novel motif prediction pipeline, Emotif Alpha, that integrates ten different motif discovery algorithms, multiple statistical tests, and a comparative analysis of conserved elements between the filarial worms Brugia malayi and Onchocerca volvulus, and the free-living nematode Caenorhabditis elegans. We identified stage-specific TF binding motifs in B. malayi, with a particular focus on those potentially involved in the L3-L4 molt, a stage important for the establishment of infection in the mammalian host. Using an in vitro molting system, we tested and validated three of these motifs demonstrating the accuracy of the motif prediction pipeline.
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http://dx.doi.org/10.1371/journal.pntd.0008275DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7337397PMC
June 2020

Nearly Complete Genome Sequence of Brugia malayi Strain FR3.

Microbiol Resour Announc 2020 Jun 11;9(24). Epub 2020 Jun 11.

Department of Biology, Center for Genomics and Systems Biology, New York University, New York, New York, USA.

Lymphatic filariasis affects ∼120 million people and can result in elephantiasis and hydrocele. Here, we report the nearly complete genome sequence of the best-studied causative agent of lymphatic filariasis, The assembly contains four autosomes, an X chromosome, and only eight gaps but lacks a contiguous sequence for the known Y chromosome.
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http://dx.doi.org/10.1128/MRA.00154-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7291094PMC
June 2020

Yeast-Expressed SARS-CoV Recombinant Receptor-Binding Domain (RBD219-N1) Formulated with Aluminum Hydroxide Induces Protective Immunity and Reduces Immune Enhancement.

bioRxiv 2020 Jul 5. Epub 2020 Jul 5.

Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, TX USA.

We developed a severe acute respiratory syndrome (SARS) subunit recombinant protein vaccine candidate based on a high-yielding, yeast- engineered, receptor-binding domain (RBD219-N1) of the SARS beta-coronavirus (SARS-CoV) spike (S) protein. When formulated with Alhydrogel®, RBD219-N1 induced high-level neutralizing antibodies against both pseudotyped virus and a clinical (mouse-adapted) isolate of SARS-CoV. Here, we report that mice immunized with RBD219-N1/Alhydrogel® were fully protected from lethal SARS-CoV challenge (0% mortality), compared to ~ 30% mortality in mice when immunized with the SARS S protein formulated with Alhydrogel®, and 100% mortality in negative controls. An RBD219-N1 formulation Alhydrogel® was also superior to the S protein, unadjuvanted RBD, and AddaVax (MF59-like adjuvant)-formulated RBD in inducing specific antibodies and preventing cellular infiltrates in the lungs upon SARS-CoV challenge. Specifically, a formulation with a 1:25 ratio of RBD219-N1 to Alhydrogel® provided high neutralizing antibody titers, 100% protection with non-detectable viral loads with minimal or no eosinophilic pulmonary infiltrates. As a result, this vaccine formulation is under consideration for further development against SARS-CoV and potentially other emerging and re-emerging beta-CoVs such as SARS-CoV-2.
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http://dx.doi.org/10.1101/2020.05.15.098079DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7263514PMC
July 2020

The Potency of an Anti-MERS Coronavirus Subunit Vaccine Depends on a Unique Combinatorial Adjuvant Formulation.

Vaccines (Basel) 2020 May 27;8(2). Epub 2020 May 27.

Laboratory of Molecular Parasitology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, NY 10065, USA.

Vaccination is one of the most successful strategies to prevent human infectious diseases. Combinatorial adjuvants have gained increasing interest as they can stimulate multiple immune pathways and enhance the vaccine efficacy of subunit vaccines. We investigated the adjuvanticity of Aluminum (alum) in combination with rASP-1, a protein adjuvant, using the Middle East respiratory syndrome coronavirus MERS-CoV receptor-binding-domain (RBD) vaccine antigen. A highly enhanced anti-MERS-CoV neutralizing antibody response was induced when mice were immunized with rASP-1 and the alum-adjuvanted RBD vaccine in two separate injection sites as compared to mice immunized with RBD + rASP-1 + alum formulated into a single inoculum. The antibodies produced also significantly inhibited the binding of RBD to its cell-associated receptor. Moreover, immunization with rASP-1 co-administered with the alum-adjuvanted RBD vaccine in separate sites resulted in an enhanced frequency of TfH and GC B cells within the draining lymph nodes, both of which were positively associated with the titers of the neutralizing antibody response related to anti-MERS-CoV protective immunity. Our findings not only indicate that this unique combinatorial adjuvanted RBD vaccine regimen improved the immunogenicity of RBD, but also point to the importance of utilizing combinatorial adjuvants for the induction of synergistic protective immune responses.
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http://dx.doi.org/10.3390/vaccines8020251DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7350031PMC
May 2020

Sex chromosome evolution in parasitic nematodes of humans.

Nat Commun 2020 04 23;11(1):1964. Epub 2020 Apr 23.

Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, 10003, USA.

Sex determination mechanisms often differ even between related species yet the evolution of sex chromosomes remains poorly understood in all but a few model organisms. Some nematodes such as Caenorhabditis elegans have an XO sex determination system while others, such as the filarial parasite Brugia malayi, have an XY mechanism. We present a complete B. malayi genome assembly and define Nigon elements shared with C. elegans, which we then map to the genomes of other filarial species and more distantly related nematodes. We find a remarkable plasticity in sex chromosome evolution with several distinct cases of neo-X and neo-Y formation, X-added regions, and conversion of autosomes to sex chromosomes from which we propose a model of chromosome evolution across different nematode clades. The phylum Nematoda offers a new and innovative system for gaining a deeper understanding of sex chromosome evolution.
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http://dx.doi.org/10.1038/s41467-020-15654-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7181701PMC
April 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

Macrofilaricidal Benzimidazole-Benzoxaborole Hybrids as an Approach to the Treatment of River Blindness: Part 2. Ketone Linked Analogs.

ACS Infect Dis 2020 02 28;6(2):180-185. Epub 2020 Jan 28.

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

The optimization of a series of benzimidazole-benzoxaborole hybrid molecules linked via a ketone that exhibit good activity against , a filarial nematode responsible for the disease onchocerciasis, also known as river blindness, is described. The lead identified in this series, (AN15470), was found to have acceptable pharmacokinetic properties to enable an evaluation following oral dosing in an animal model of onchocerciasis. Compound was effective in killing worms implanted in Mongolian gerbils when dosed orally as a suspension at 100 mg/kg/day for 14 days but not when dosed orally at 100 mg/kg/day for 7 days.
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http://dx.doi.org/10.1021/acsinfecdis.9b00397DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7026882PMC
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

Pyruvate produced by Brugia spp. via glycolysis is essential for maintaining the mutualistic association between the parasite and its endosymbiont, Wolbachia.

PLoS Pathog 2019 09 30;15(9):e1008085. Epub 2019 Sep 30.

Molecular Parasitology, New York Blood Center, New York, New York, United States of America.

Human parasitic nematodes are the causative agents of lymphatic filariasis (elephantiasis) and onchocerciasis (river blindness), diseases that are endemic to more than 80 countries and that consistently rank in the top ten for the highest number of years lived with disability. These filarial nematodes have evolved an obligate mutualistic association with an intracellular bacterium, Wolbachia, a symbiont that is essential for the successful development, reproduction, and survival of adult filarial worms. Elimination of the bacteria causes adult worms to die, making Wolbachia a primary target for developing new interventional tools to combat filariases. To further explore Wolbachia as a promising indirect macrofilaricidal drug target, the essential cellular processes that define the symbiotic Wolbachia-host interactions need to be identified. Genomic analyses revealed that while filarial nematodes encode all the enzymes necessary for glycolysis, Wolbachia does not encode the genes for three glycolytic enzymes: hexokinase, 6-phosphofructokinase, and pyruvate kinase. These enzymes are necessary for converting glucose into pyruvate. Wolbachia, however, has the full complement of genes required for gluconeogenesis starting with pyruvate, and for energy metabolism via the tricarboxylic acid cycle. Therefore, we hypothesized that Wolbachia might depend on host glycolysis to maintain a mutualistic association with their parasitic host. We did conditional experiments in vitro that confirmed that glycolysis and its end-product, pyruvate, sustain this symbiotic relationship. Analysis of alternative sources of pyruvate within the worm indicated that the filarial lactate dehydrogenase could also regulate the local intracellular concentration of pyruvate in proximity to Wolbachia and thus help control bacterial growth via molecular interactions with the bacteria. Lastly, we have shown that the parasite's pyruvate kinase, the enzyme that performs the last step in glycolysis, could be a potential novel anti-filarial drug target. Establishing that glycolysis is an essential component of symbiosis in filarial worms could have a broader impact on research focused on other intracellular bacteria-host interactions where the role of glycolysis in supporting intracellular survival of bacteria has been reported.
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http://dx.doi.org/10.1371/journal.ppat.1008085DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6791551PMC
September 2019

Emodepside has sex-dependent immobilizing effects on adult Brugia malayi due to a differentially spliced binding pocket in the RCK1 region of the SLO-1 K channel.

PLoS Pathog 2019 09 25;15(9):e1008041. Epub 2019 Sep 25.

Department of Biomedical Sciences, Iowa State University, Ames, Iowa, United States of America.

Filariae are parasitic nematodes that are transmitted to their definitive host as third-stage larvae by arthropod vectors like mosquitoes. Filariae cause diseases including: lymphatic filariasis with distressing and disturbing symptoms like elephantiasis; and river blindness. Filarial diseases affect millions of people in 73 countries throughout the topics and sub-tropics. The drugs available for mass drug administration, (ivermectin, albendazole and diethylcarbamazine), are ineffective against adult filariae (macrofilariae) at the registered dosing regimen; this generates a real and urgent need to identify effective macrofilaricides. Emodepside, a veterinary anthelmintic registered for treatment of nematode infections in cats and dogs, is reported to have macrofilaricidal effects. Here, we explore the mode of action of emodepside using adult Brugia malayi, one of the species that causes lymphatic filariasis. Whole-parasite motility measurement with Worminator and patch-clamp of single muscle cells show that emodepside potently inhibits motility by activating voltage-gated potassium channels and that the male is more sensitive than the female. RNAi knock down suggests that emodepside targets SLO-1 K channels. We expressed slo-1 isoforms, with alternatively spliced exons at the RCK1 (Regulator of Conductance of Potassium) domain, heterologously in Xenopus laevis oocytes. We discovered that the slo-1f isoform, found in muscles of males, is more sensitive to emodepside than the slo-1a isoform found in muscles of females; and selective RNAi of the slo-1a isoform in female worms increased emodepside potency. In Onchocerca volvulus, that causes river blindness, we found two isoforms in adult females with homology to Bma-SLO-1A and Bma-SLO-1F at the RCK1 domain. In silico modeling identified an emodepside binding pocket in the same RCK1 region of different species of filaria that is affected by these splice variations. Our observations show that emodepside has potent macrofilaricidal effects and alternative splicing in the RCK1 binding pocket affects potency. Therefore, the evaluation of potential sex-dependent effects of an anthelmintic compound is of importance to prevent any under-dosing of one or the other gender of nematodes once given to patients.
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http://dx.doi.org/10.1371/journal.ppat.1008041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6779273PMC
September 2019

Antibody responses against the vaccine antigens Ov-103 and Ov-RAL-2 are associated with protective immunity to Onchocerca volvulus infection in both mice and humans.

PLoS Negl Trop Dis 2019 09 16;13(9):e0007730. Epub 2019 Sep 16.

Laboratory of Molecular Parasitology, Lindsley F Kimball Research Institute, New York Blood Center, New York, New York, United States of America.

Background: The current strategy for the elimination of onchocerciasis is based on annual or bi-annual mass drug administration with ivermectin. However, due to several limiting factors there is a growing concern that elimination of onchocerciasis cannot be achieved solely through the current strategy. Additional tools are critically needed including a prophylactic vaccine. Presently Ov-103 and Ov-RAL-2 are the most promising vaccine candidates against an Onchocerca volvulus infection.

Methodology/principal Findings: Protection induced by immunization of mice with the alum-adjuvanted Ov-103 or Ov-RAL-2 vaccines appeared to be antibody dependent since AID-/- mice that could not mount antigen-specific IgG antibody responses were not protected from an Onchocerca volvulus challenge. To determine a possible association between antigen-specific antibody responses and anti-larvae protective immunity in humans, we analyzed the presence of anti-Ov-103 and anti-Ov-RAL-2 cytophilic antibody responses (IgG1 and IgG3) in individuals classified as putatively immune, and in infected individuals who developed concomitant immunity with age. It was determined that 86% of putatively immune individuals and 95% individuals with concomitant immunity had elevated IgG1 and IgG3 responses to Ov-103 and Ov-RAL-2. Based on the elevated chemokine levels associated with protection in the Ov-103 or Ov-RAL-2 immunized mice, the profile of these chemokines was also analyzed in putatively immune and infected individuals; both groups contained significantly higher levels of KC, IP-10, MCP-1 and MIP-1β in comparison to normal human sera. Moreover, human monospecific anti-Ov-103 antibodies but not anti-Ov-RAL-2 significantly inhibited the molting of third-stage larvae (L3) in vitro by 46% in the presence of naïve human neutrophils, while both anti-Ov-103 and anti-Ov-RAL-2 antibodies significantly inhibited the molting by 70-80% when cultured in the presence of naive human monocytes. Interestingly, inhibition of molting by Ov-103 antibodies and monocytes was only in part dependent on contact with the cells, while inhibition of molting with Ov-RAL-2 antibodies was completely dependent on contact with the monocytes. In comparison, significant levels of parasite killing in Ov-103 and Ov-RAL-2 vaccinated mice only occurred when cells enter the parasite microenvironment. Taken together, antibodies to Ov-103 and Ov-RAL-2 and cells are required for protection in mice as well as for the development of immunity in humans.

Conclusions/significance: Alum-adjuvanted Ov-103 and Ov-RAL-2 vaccines have the potential of reducing infection and thus morbidity associated with onchocerciasis in humans. The development of cytophilic antibodies, that function in antibody-dependent cellular cytotoxicity, is essential for a successful prophylactic vaccine against this infection.
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http://dx.doi.org/10.1371/journal.pntd.0007730DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6762197PMC
September 2019

Development and validation of an Onchocerca ochengi adult male worm gerbil model for macrofilaricidal drug screening.

PLoS Negl Trop Dis 2019 07 1;13(7):e0007556. Epub 2019 Jul 1.

Lindsley F. Kimball Research Institute, New York City, New York, United States of America.

Background: Onchocerciasis currently afflicts an estimated 15 million people and is the second leading infectious cause of blindness world-wide. The development of a macrofilaricide to cure the disease has been hindered by the lack of appropriate small laboratory animal models. This study therefore, was aimed at developing and validating the Mongolian gerbil, as an Onchocerca ochengi (the closest in phylogeny to O. volvulus) adult male worm model.

Methodology/principal Findings: Mongolian gerbils (Meriones unguiculatus) were each implanted with 20 O. ochengi male worms (collected from infected cattle), in the peritoneum. Following drug or placebo treatments, the implanted worms were recovered from the animals and analyzed for burden, motility and viability. Worm recovery in control gerbils was on average 35%, with 89% of the worms being 100% motile. Treatment of the gerbils implanted with male worms with flubendazole (FBZ) resulted in a significant reduction (p = 0.0021) in worm burden (6.0% versus 27.8% in the control animals); all recovered worms from the treated group had 0% worm motility versus 91.1% motility in control animals. FBZ treatment had similar results even after four different experiments. Using this model, we tested a related drug, oxfendazole (OFZ), and found it to also significantly (p = 0.0097) affect worm motility (22.7% versus 95.0% in the control group).

Conclusions/significance: We have developed and validated a novel gerbil O. ochengi adult male worm model for testing new macrofilaricidal drugs in vivo. It was also used to determine the efficacy of oxfendazole in vivo.
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http://dx.doi.org/10.1371/journal.pntd.0007556DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6625737PMC
July 2019

Integrating Multiple Biomarkers to Increase Sensitivity for the Detection of Onchocerca volvulus Infection.

J Infect Dis 2020 05;221(11):1805-1815

Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland.

Background: Serological assessments for human onchocerciasis are based on IgG4 reactivity against the OV-16 antigen, with sensitivities of 60-80%. We have previously identified 7 novel proteins that could improve serodiagnosis.

Methods: IgG4 responses to these 7 proteins were assessed by luciferase immunoprecipitation (LIPS) and enzyme-linked immunosorbent (ELISA) immunoassays.

Results: OVOC10469 and OVOC3261 were identified as the most promising candidates by IgG4-based immunoassays with sensitivities of 53% for rOVOC10469 and 78% for rOVOC3261 while specificity for each was >99%. These 2 antigens in combination with OV-16 increased the sensitivity for patent infections to 94%. The kinetics of appearance of these IgG4 responses based on experimentally infected non-human primates indicated that they were microfilarial- driven. Further, the IgG4 responses to both OVOC10469 and OVOC3261 (as well as to OV-16) drop significantly (p<0.05) following successful treatment for onchocerciasis. A prototype lateral flow rapid diagnostic test to detect IgG4 to both Ov-16 and OVOC3261 was developed and tested demonstrating an overall 94% sensitivity.

Conclusion: The combined use of rOVOC3261 with OV-16 improved serologic assessment of O. volvulus infection, a current unmet need toward the goal of elimination of transmission of O. volvulus.
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http://dx.doi.org/10.1093/infdis/jiz307DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7213562PMC
May 2020

Development of a preliminary in vitro drug screening assay based on a newly established culturing system for pre-adult fifth-stage Onchocerca volvulus worms.

PLoS Negl Trop Dis 2019 01 17;13(1):e0007108. Epub 2019 Jan 17.

Molecular Parasitology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America.

Background: The human filarial parasite Onchocerca volvulus is the causative agent of onchocerciasis (river blindness). It causes blindness in 270,000 individuals with an additional 6.5 million suffering from severe skin pathologies. Current international control programs focus on the reduction of microfilaridermia by annually administering ivermectin for more than 20 years with the ultimate goal of blocking of transmission. The adult worms of O. volvulus can live within nodules for over 15 years and actively release microfilariae for the majority of their lifespan. Therefore, protracted treatment courses of ivermectin are required to block transmission and eventually eliminate the disease. To shorten the time to elimination of this disease, drugs that successfully target macrofilariae (adult parasites) are needed. Unfortunately, there is no small animal model for the infection that could be used for discovery and screening of drugs against adult O. volvulus parasites. Here, we present an in vitro culturing system that supports the growth and development of O. volvulus young adult worms from the third-stage (L3) infective stage.

Methodology/principal Findings: In this study we optimized the culturing system by testing several monolayer cell lines to support worm growth and development. We have shown that the optimized culturing system allows for the growth of the L3 worms to L5 and that the L5 mature into young adult worms. Moreover, these young O. volvulus worms were used in preliminary assays to test putative macrofilaricidal drugs and FDA-approved repurposed drugs.

Conclusion: The culture system we have established for O. volvulus young adult worms offers a promising new platform to advance drug discovery against the human filarial parasite, O. volvulus and thus supports the continuous pursuit for effective macrofilaricidal drugs. However, this in vitro culturing system will have to be further validated for reproducibility before it can be rolled out as a drug screen for decision making in macrofilaricide drug development programs.
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http://dx.doi.org/10.1371/journal.pntd.0007108DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6353222PMC
January 2019

Efficacy of subcutaneous doses and a new oral amorphous solid dispersion formulation of flubendazole on male jirds (Meriones unguiculatus) infected with the filarial nematode Brugia pahangi.

PLoS Negl Trop Dis 2019 01 16;13(1):e0006787. Epub 2019 Jan 16.

Dept. of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America.

River blindness and lymphatic filariasis are two filarial diseases that globally affect millions of people mostly in impoverished countries. Current mass drug administration programs rely on drugs that primarily target the microfilariae, which are released from adult female worms. The female worms can live for several years, releasing millions of microfilariae throughout the course of infection. Thus, to stop transmission of infection and shorten the time to elimination of these diseases, a safe and effective drug that kills the adult stage is needed. The benzimidazole anthelmintic flubendazole (FBZ) is 100% efficacious as a macrofilaricide in experimental filarial rodent models but it must be administered subcutaneously (SC) due to its low oral bioavailability. Studies were undertaken to assess the efficacy of a new oral amorphous solid dispersion (ASD) formulation of FBZ on Brugia pahangi infected jirds (Meriones unguiculatus) and compare it to a single or multiple doses of FBZ given subcutaneously. Results showed that worm burden was not significantly decreased in animals given oral doses of ASD FBZ (0.2-15 mg/kg). Regardless, doses as low as 1.5 mg/kg caused extensive ultrastructural damage to developing embryos and microfilariae (mf). SC injections of FBZ in suspension (10 mg/kg) given for 5 days however, eliminated all worms in all animals, and a single SC injection reduced worm burden by 63% compared to the control group. In summary, oral doses of ASD formulated FBZ did not significantly reduce total worm burden but longer treatments, extended takedown times or a second dosing regimen, may decrease female fecundity and the number of mf shed by female worms.
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http://dx.doi.org/10.1371/journal.pntd.0006787DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334909PMC
January 2019

Development of Onchocerca volvulus in humanized NSG mice and detection of parasite biomarkers in urine and serum.

PLoS Negl Trop Dis 2018 12 12;12(12):e0006977. Epub 2018 Dec 12.

Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia Pennsylvania, United States of America.

Background: The study of Onchocerca volvulus has been limited by its host range, with only humans and non-human primates shown to be susceptible to the full life cycle infection. Small animal models that support the development of adult parasites have not been identified.

Methodology/principal Findings: We hypothesized that highly immunodeficient NSG mice would support the survival and maturation of O. volvulus and alteration of the host microenvironment through the addition of various human cells and tissues would further enhance the level of parasite maturation. NSG mice were humanized with: (1) umbilical cord derived CD34+ stem cells, (2) fetal derived liver, thymus and CD34+ stem cells or (3) primary human skeletal muscle cells. NSG and humanized NSG mice were infected with 100 O. volvulus infective larvae (L3) for 4 to 12 weeks. When necropsies of infected animals were performed, it was observed that parasites survived and developed throughout the infection time course. In each of the different humanized mouse models, worms matured from L3 to advanced fourth stage larvae, with both male and female organ development. In addition, worms increased in length by up to 4-fold. Serum and urine, collected from humanized mice for identification of potential biomarkers of infection, allowed for the identification of 10 O. volvulus-derived proteins found specifically in either the urine or the serum of the humanized O. volvulus-infected NSG mice.

Conclusions/significance: The newly identified mouse models for onchocerciasis will enable the development of O. volvulus specific biomarkers, screening for new therapeutic approaches and potentially studying the human immune response to infection with O. volvulus.
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http://dx.doi.org/10.1371/journal.pntd.0006977DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6306240PMC
December 2018

Ligand binding properties of two Brugia malayi fatty acid and retinol (FAR) binding proteins and their vaccine efficacies against challenge infection in gerbils.

PLoS Negl Trop Dis 2018 10 8;12(10):e0006772. Epub 2018 Oct 8.

Department of Pathobiological Sciences, LSU School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, United States of America.

Parasitic nematodes produce an unusual class of fatty acid and retinol (FAR)-binding proteins that may scavenge host fatty acids and retinoids. Two FARs from Brugia malayi (Bm-FAR-1 and Bm-FAR-2) were expressed as recombinant proteins, and their ligand binding, structural characteristics, and immunogenicities examined. Circular dichroism showed that rBm-FAR-1 and rBm-FAR-2 are similarly rich in α-helix structure. Unexpectedly, however, their lipid binding activities were found to be readily differentiated. Both FARs bound retinol and cis-parinaric acid similarly, but, while rBm-FAR-1 induced a dramatic increase in fluorescence emission and blue shift in peak emission by the fluorophore-tagged fatty acid (dansyl-undecanoic acid), rBm-FAR-2 did not. Recombinant forms of the related proteins from Onchocerca volvulus, rOv-FAR-1 and rOv-FAR-2, were found to be similarly distinguishable. This is the first FAR-2 protein from parasitic nematodes that is being characterized. The relative protein abundance of Bm-FAR-1 was higher than Bm-FAR-2 in the lysates of different developmental stages of B. malayi. Both FAR proteins were targets of strong IgG1, IgG3 and IgE antibody in infected individuals and individuals who were classified as endemic normal or putatively immune. In a B. malayi infection model in gerbils, immunization with rBm-FAR-1 and rBm-FAR-2 formulated in a water-in-oil-emulsion (®Montanide-720) or alum elicited high titers of antigen-specific IgG, but only gerbils immunized with rBm-FAR-1 formulated with the former produced a statistically significant reduction in adult worms (68%) following challenge with B. malayi infective larvae. These results suggest that FAR proteins may play important roles in the survival of filarial nematodes in the host, and represent potential candidates for vaccine development against lymphatic filariasis and related filarial infections.
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http://dx.doi.org/10.1371/journal.pntd.0006772DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6193737PMC
October 2018

Cysteine proteases during larval migration and development of helminths in their final host.

PLoS Negl Trop Dis 2018 08 23;12(8):e0005919. Epub 2018 Aug 23.

Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America.

Neglected tropical diseases caused by metazoan parasites are major public health concerns, and therefore, new methods for their control and elimination are needed. Research over the last 25 years has revealed the vital contribution of cysteine proteases to invasion of and migration by (larval) helminth parasites through host tissues, in addition to their roles in embryogenesis, molting, egg hatching, and yolk degradation. Their central function to maintaining parasite survival in the host has made them prime intervention targets for novel drugs and vaccines. This review focuses on those helminth cysteine proteases that have been functionally characterized during the varied early stages of development in the human host and embryogenesis.
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http://dx.doi.org/10.1371/journal.pntd.0005919DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6107106PMC
August 2018

Development of a toolkit for piggyBac-mediated integrative transfection of the human filarial parasite Brugia malayi.

PLoS Negl Trop Dis 2018 05 21;12(5):e0006509. Epub 2018 May 21.

Center for Global Health Infectious Disease Research, Department of Global Health, University of South Florida, Tampa, FL, United States of America.

Background: The human filarial parasites cause diseases that are among the most important causes of morbidity in the developing world. The elimination programs targeting these infections rely on a limited number of drugs, making the identification of new chemotherapeutic agents a high priority. The study of these parasites has lagged due to the lack of reverse genetic methods.

Methodology/principal Findings: We report a novel co-culture method that results in developmentally competent infective larvae of one of the human filarial parasites (Brugia malayi) and describe a method to efficiently transfect the larval stages of this parasite. We describe the production of constructs that result in integrative transfection using the piggyBac transposon system, and a selectable marker that can be used to identify transgenic parasites. We describe the production and use of dual reporter plasmids containing both a secreted luciferase selectable marker and fluorescent protein reporters that will be useful to study temporal and spatial patterns of gene expression.

Conclusions/significance: The methods and constructs reported here will permit the efficient production of integrated transgenic filarial parasite lines, allowing reverse genetic technologies to be applied to all life cycle stages of the parasite.
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http://dx.doi.org/10.1371/journal.pntd.0006509DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5983866PMC
May 2018

The parasite-derived rOv-ASP-1 is an effective antigen-sparing CD4 T cell-dependent adjuvant for the trivalent inactivated influenza vaccine, and functions in the absence of MyD88 pathway.

Vaccine 2018 06;36(25):3650-3665

Laboratory of Molecular Parasitology, Lindsley F Kimball Research Institute, New York Blood Center, New York, NY 10065, United States. Electronic address:

Vaccination remains the most cost-effective biomedical approach for controlling influenza disease. In times of pandemics, however, these vaccines cannot be produced in sufficient quantities for worldwide use by the current manufacturing capacities and practices. What is needed is the development of adjuvanted vaccines capable of inducing an adequate or better immune response at a decreased antigen dose. Previously we showed that the protein adjuvant rOv-ASP-1 augments influenza-specific antibody titers and survival after virus challenge in both young adult and old-age mice when administered with the trivalent inactivated influenza vaccine (IIV3). In this study we show that a reduced amount of rOv-ASP-1, with 40-times less IIV3 can also induce protection. Apparently the potency of the rOv-ASP-1 adjuvanted IIV3 vaccine is independent of the IIV3-specific Th1/Th2 associated antibody responses, and independent of the presence of HAI antibodies. However, CD4 T helper cells were indispensable for the protection. Further, rOv-ASP-1 with or without IIV3 elicited the increased level of various chemokines, which are known chemoattractant for immune cells, into the muscle 4 h after immunization, and significantly induced the recruitment of monocytes, macrophages and neutrophils into the muscles. The recruited monocytes had higher expression of the activation marker MHCII on their surface as well as CXCR3 and CCR2; receptors for IP-10 and MCP-1, respectively. These results show that the rOv-ASP-1 adjuvant allows substantial antigen sparing of IIV3 by stimulating at the site of injection the accumulation of chemokines and the recruitment of immune cells that can augment the activation of CD4 T cell immune responses, essential for the production of antibody responses. Protection elicited by the rOv-ASP-1 adjuvanted IIV3 vaccine also appears to function in the absence of MyD88-signaling. Future studies will attempt to delineate the precise mechanisms by which the rOv-ASP-1 adjuvanted IIV3 vaccine works.
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http://dx.doi.org/10.1016/j.vaccine.2018.05.029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6595497PMC
June 2018

Onchocerca volvulus: The Road from Basic Biology to a Vaccine.

Trends Parasitol 2018 01 22;34(1):64-79. Epub 2017 Sep 22.

Texas Children's Hospital Center for Vaccine Development, Department of Pediatrics, Section of Pediatric Tropical Medicine, National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, USA.

Human onchocerciasis - commonly known as river blindness - is one of the most devastating yet neglected tropical diseases, leaving many millions in sub-Saharan Africa blind and/or with chronic disabilities. Attempts to eliminate onchocerciasis, primarily through the mass drug administration of ivermectin, remains challenging and has been heightened by the recent news that drug-resistant parasites are developing in some populations after years of drug treatment. Needed, and needed now, in the fight to eliminate onchocerciasis are new tools, such as preventive and therapeutic vaccines. This review summarizes the progress made to advance the onchocerciasis vaccine from the research laboratory into the clinic.
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http://dx.doi.org/10.1016/j.pt.2017.08.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5748257PMC
January 2018

Defining the target and the effect of imatinib on the filarial c-Abl homologue.

PLoS Negl Trop Dis 2017 Jul 20;11(7):e0005690. Epub 2017 Jul 20.

Laboratory of Parasitic Diseases, Helminth Immunology Section, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, United States of America.

Background: Previously we demonstrated the micro- and macrofilaricidal properties of imatinib in vitro. Here we use electron and multiphoton microscopy to define the target of imatinib in the adult and microfilarial stages of Brugia malayi and assess the effects of pharmacologically relevant levels of imatinib on the adult parasites.

Methods: After fixation of adult B. malayi males and females, sections were stained with polyclonal rabbit anti-c-Abl antibody (or isotype control) and imaged with multiphoton fluorescent microscopy. Microfilariae were fixed and labeled with rabbit anti-c-Abl IgG primary antibody followed by anti-rabbit gold conjugated secondary antibody and imaged using transmission electron microscopy (TEM; immunoEM). In addition, adult B. malayi males and females were exposed to 0 or 10μM of imatinib for 7 days following which they were prepared for transmission electron microscopy (TEM) to assess the drug's effect on filarial ultrastructure.

Results: Fluorescent localization of anti-c-Abl antibody demonstrated widespread uptake in the adult filariae, but the most intense signal was seen in the reproductive organs, muscle, and intestine of both male and female worms. Fluorescence was significantly more intense in the early microfilarial stage (i.e. early morula) compared with later development stages (i.e. pretzel). Anti-c-Abl antibody in the microfilariae localized to the nuclei. Based on TEM assessment following imatinib exposure, imatinib appeared to be detrimental to embryogenesis in the adult female B. malayi.

Conclusions: At pharmacologically achievable concentrations of imatinib, embryogenesis is impaired and possibly halted in adult filariae. Imatinib is likely a slow microfilaricide due to interference in intra-nuclear processes, which are slowly detrimental to the parasite and not immediately lethal, and thus may be used to lower the levels of L. loa microfilariae before they are treated within the context of conventional mass drug administration.
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http://dx.doi.org/10.1371/journal.pntd.0005690DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5538754PMC
July 2017
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