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Panzner U, Excler JL, Kim JH, Marks F, Carter D, Siddiqui AA. Recent Advances and Methodological Considerations on Vaccine Candidates for Human Schistosomiasis. FRONTIERS IN TROPICAL DISEASES 2021. [DOI: 10.3389/fitd.2021.719369] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Schistosomiasis remains a neglected tropical disease of major public health concern with high levels of morbidity in various parts of the world. Although considerable efforts in implementing mass drug administration programs utilizing praziquantel have been deployed, schistosomiasis is still not contained. A vaccine may therefore be an essential part of multifaceted prevention control efforts. In the 1990s, a joint United Nations committee promoting parasite vaccines shortlisted promising candidates including for schistosomiasis discussed below. After examining the complexity of immune responses in human hosts infected with schistosomes, we review and discuss the antigen design and preclinical and clinical development of the four leading vaccine candidates: Sm-TSP-2 in Phase 1b/2b, Sm14 in Phase 2a/2b, Sm-p80 in Phase 1 preparation, and Sh28GST in Phase 3. Our assessment of currently leading vaccine candidates revealed some methodological issues that preclude a fair comparison between candidates and the rationale to advance in clinical development. These include (1) variability in animal models - in particular non-human primate studies - and predictive values of each for protection in humans; (2) lack of consensus on the assessment of parasitological and immunological parameters; (3) absence of reliable surrogate markers of protection; (4) lack of well-designed parasitological and immunological natural history studies in the context of mass drug administration with praziquantel. The controlled human infection model - while promising and unique - requires validation against efficacy outcomes in endemic settings. Further research is also needed on the impact of advanced adjuvants targeting specific parts of the innate immune system that may induce potent, protective and durable immune responses with the ultimate goal of achieving meaningful worm reduction.
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Molehin AJ, Gray SA, Turner C, Davis J, Zhang W, Khatoon S, Rattan M, Kernen R, Peterson C, Sennoune SR, Carter D, Siddiqui AA. Process Development of Sj-p80: A Low-Cost Transmission-Blocking Veterinary Vaccine for Asiatic Schistosomiasis. Front Immunol 2021; 11:578715. [PMID: 33732227 PMCID: PMC7959798 DOI: 10.3389/fimmu.2020.578715] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 12/30/2020] [Indexed: 11/16/2022] Open
Abstract
Asiatic schistosomiasis caused by Schistosoma japonicum is a neglected tropical disease resulting in significant morbidity to both humans and animals - particularly bovines - in endemic areas. Infection with this parasite leads to less healthy herds, causing problems in communities which rely on bovines for farming, milk and meat production. Additionally, excretion of parasite eggs in feces perpetuates the life cycle and can lead to human infection. We endeavored to develop a minimally purified, inexpensive, and effective vaccine based on the 80 kDa large subunit of the calcium activated neutral protease (calpain) from S. japonicum (Sj-p80). Here we describe the production of veterinary vaccine-grade Sj-p80 at four levels of purity and demonstrate in a pilot study that minimally purified antigen provides protection against infection in mice when paired with a low-cost veterinary adjuvant, Montanide™ ISA61 VG. Preliminary data demonstrate that the vaccine is immunogenic with robust antibody titers following immunization, and vaccination resulted in a reduction of parasite eggs being deposited in the liver (23.4-51.4%) and intestines (1.9-55.1%) depending on antigen purity as well as reducing the ability of these eggs to hatch into miracidia by up to 31.6%. We therefore present Sj-p80 as a candidate vaccine antigen for Asiatic schistosomiasis which is now primed for continued development and testing in bovines in endemic areas. A successful bovine vaccine could play a major role in reducing pathogen transmission to humans by interrupting the parasitic life cycle and improving quality of life for people living in endemic countries.
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Affiliation(s)
- Adebayo J. Molehin
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
- Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Sean A. Gray
- PAI Life Sciences Inc, Seattle, WA, United States
| | - Cheri Turner
- PAI Life Sciences Inc, Seattle, WA, United States
| | | | - Weidong Zhang
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
- Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Sabiha Khatoon
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
- Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Madison Rattan
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Rebecca Kernen
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Christopher Peterson
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Souad R. Sennoune
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | | | - Afzal A. Siddiqui
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
- Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
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Zhang W, Ahmad G, Molehin AJ, Torben W, Le L, Kim E, Lazarus S, Siddiqui AJ, Carter D, Siddiqui AA. Schistosoma mansoni antigen Sm-p80: prophylactic efficacy using TLR4 agonist vaccine adjuvant glucopyranosyl lipid A-Alum in murine and non-human primate models. J Investig Med 2018; 66:1124-1132. [PMID: 29997146 PMCID: PMC6288690 DOI: 10.1136/jim-2018-000786] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/03/2018] [Indexed: 01/06/2023]
Abstract
Sm-p80, the large subunit of Schistosoma mansoni calpain, is a leading candidate for a schistosomiasis vaccine. The prophylactic and antifecundity efficacy of Sm-p80 has been tested in three animal models (mouse, hamster and baboon) using a multitude of vaccine formulations and approaches. In our continual effort to enhance the vaccine efficacy, in this study, we have utilized the adjuvant, synthetic hexa-acylated lipid A derivative, glucopyranosyl lipid A (GLA) formulated in aluminum (GLA-Alum) with recombinant Sm-p80. The rSm-p80+GLA-Alum immunization regimen provided 33.33%–53.13% reduction in worm burden in the mouse model and 38% worm burden reduction in vaccinated baboons. Robust Sm-p80-specific immunoglobulin (Ig)G, IgG1, IgG2a and IgM responses were observed in all immunized animals. The rSm-p80+GLA-Alum coadministration induced a mix of T-helper (Th) cells (Th1, Th2 and Th17) responses as determined via the release of interleukin (IL)-2, IL-4, IL-18, IL-21, IL-22 and interferon-γ.
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Affiliation(s)
- Weidong Zhang
- Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas, USA.,Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - Gul Ahmad
- Department of Natural Sciences, School of Arts & Sciences, Peru State College, Peru, Nebraska, USA
| | - Adebayo J Molehin
- Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas, USA.,Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - Workineh Torben
- Comparative Pathology/Immunology, Tulane National Primate Research Center, Covington, Louisiana, USA
| | - Loc Le
- Bladder Immunology Group, Biomedical Research Institute, Rockville, Maryland, USA
| | - Eunjee Kim
- Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas, USA.,Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - Samra Lazarus
- Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas, USA.,Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - Arif J Siddiqui
- Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas, USA.,Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | | | - Afzal A Siddiqui
- Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas, USA.,Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
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Siddiqui AJ, Molehin AJ, Zhang W, Ganapathy PK, Kim E, Rojo JU, Redman WK, Sennoune SR, Sudduth J, Freeborn J, Hunter D, Kottapalli KR, Kottapalli P, Wettashinghe R, van Dam GJ, Corstjens PLAM, Papin JF, Carey D, Torben W, Ahmad G, Siddiqui AA. Sm-p80-based vaccine trial in baboons: efficacy when mimicking natural conditions of chronic disease, praziquantel therapy, immunization, and Schistosoma mansoni re-encounter. Ann N Y Acad Sci 2018; 1425:19-37. [PMID: 29888790 DOI: 10.1111/nyas.13866] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 04/27/2018] [Accepted: 05/02/2018] [Indexed: 11/28/2022]
Abstract
Sm-p80-based vaccine efficacy for Schistosoma mansoni was evaluated in a baboon model of infection and disease. The study was designed to replicate a human vaccine implementation scenario for endemic regions in which vaccine would be administered following drug treatment of infected individuals. In our study, the Sm-p80-based vaccine reduced principal pathology producing hepatic egg burdens by 38.0% and egg load in small and large intestines by 72.2% and 49.4%, respectively, in baboons. Notably, hatching rates of eggs recovered from liver and small and large intestine of vaccinated animals were significantly reduced, by 60.4%, 48.6%, and 82.3%, respectively. Observed reduction in egg maturation/hatching rates was supported by immunofluorescence and confocal microscopy showing unique differences in Sm-p80 expression in worms of both sexes and matured eggs. Vaccinated baboons had a 64.5% reduction in urine schistosome circulating anodic antigen, a parameter that reflects worm numbers/health status in infected hosts. Preliminary analyses of RNA sequencing revealed unique genes and canonical pathways associated with establishment of chronic disease, praziquantel-mediated parasite killing, and Sm-p80-mediated protection in vaccinated baboons. Overall, our study demonstrated efficacy of the Sm-p80 vaccine and provides insight into some of the epistatic interactions associated with protection.
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Affiliation(s)
- Arif J Siddiqui
- School of Medicine, Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas.,Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Adebayo J Molehin
- School of Medicine, Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas.,Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Weidong Zhang
- School of Medicine, Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas.,Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Pramodh K Ganapathy
- School of Medicine, Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas.,Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Eunjee Kim
- School of Medicine, Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas.,Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Juan U Rojo
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire
| | - Whitni K Redman
- School of Medicine, Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas.,Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Souad R Sennoune
- School of Medicine, Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas.,Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Justin Sudduth
- School of Medicine, Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas.,Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Jasmin Freeborn
- School of Medicine, Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas.,Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Derick Hunter
- School of Medicine, Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas.,Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | | | - Pratibha Kottapalli
- Center for Biotechnology and Genomics, Texas Tech University, Lubbock, Texas
| | | | - Govert J van Dam
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Paul L A M Corstjens
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - James F Papin
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - David Carey
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Workineh Torben
- Division of Comparative Pathology, Tulane National Primate Research Center, Covington, Louisiana
| | - Gul Ahmad
- Department of Biology, School of Arts & Sciences, Peru State College, Peru, Nebraska
| | - Afzal A Siddiqui
- School of Medicine, Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, Texas.,Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
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Schistosoma egg-induced liver pathology resolution by Sm-p80-based schistosomiasis vaccine in baboons. Pathology 2018; 50:442-449. [PMID: 29739616 DOI: 10.1016/j.pathol.2018.01.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 12/22/2017] [Accepted: 01/11/2018] [Indexed: 01/20/2023]
Abstract
Schistosomiasis remains a serious chronic debilitating hepato-intestinal disease. Current control measures based on mass drug administration are inadequate due to sustained re-infection rates, low treatment coverage and emergence of drug resistance. Hence, there is an urgent need for a schistosomiasis vaccine for disease control. In this study, we assessed the anti-pathology efficacy of Schistosoma mansoni large subunit of calpain (Sm-p80)-based vaccine against schistosomiasis caused by infections with Schistosoma mansoni in baboons. We also evaluated the disease transmission-blocking potential of Sm-p80 vaccine. Immunisations with Sm-p80-based vaccine resulted in significant reduction of hepatic egg load in vaccinated baboons (67.7% reduction, p = 0.0032) when compared to the control animals, indicative of reduction in pathology. There was also a significant reduction in sizes of egg-induced granulomas in baboons immunised with Sm-p80 vaccine compared to their control counterparts. Egg hatching rate analysis revealed an overall 85.6% reduction (p = 0.0018) in vaccinated animals compared to the controls, highlighting the potential role of Sm-p80 vaccine in disease transmission. The findings on anti-pathology efficacy and transmission-blocking potential presented in this study have formed the basis for a large-scale double-blinded baboon experiment that is currently underway.
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Mekonnen GG, Pearson M, Loukas A, Sotillo J. Extracellular vesicles from parasitic helminths and their potential utility as vaccines. Expert Rev Vaccines 2018; 17:197-205. [PMID: 29353519 DOI: 10.1080/14760584.2018.1431125] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Helminths are multicellular parasites affecting nearly three billion people worldwide. To orchestrate a parasitic existence, helminths secrete different molecules, either in soluble form or contained within extracellular vesicles (EVs). EVs are secreted by most cell types and organisms, and have varied roles in intercellular communication, including immune modulation and pathogenesis. AREAS COVERED In this review, we describe the nucleic acid and proteomic composition of EVs from helminths, with a focus on the protein vaccine candidates present on the EV surface membrane, and discuss the potential utility of helminth EVs and their constituent proteins in the fight against helminth infections. EXPERT COMMENTARY A significant number of proteins present in helminth-secreted EVs are known vaccine candidates. The characterization of helminth EV proteomes will shed light on host-pathogen interactions, facilitate the discovery of new diagnostic biomarkers, and provide a novel approach for the development of new control measures against helminth infections.
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Affiliation(s)
- Gebeyaw Getnet Mekonnen
- a Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute of Tropical Health and Medicine , James Cook University , Cairns , Australia.,b Department of Medical Parasitology , School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar , Gondar , Ethiopia
| | - Mark Pearson
- a Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute of Tropical Health and Medicine , James Cook University , Cairns , Australia
| | - Alex Loukas
- a Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute of Tropical Health and Medicine , James Cook University , Cairns , Australia
| | - Javier Sotillo
- a Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute of Tropical Health and Medicine , James Cook University , Cairns , Australia
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Molehin AJ, Sennoune SR, Zhang W, Rojo JU, Siddiqui AJ, Herrera KA, Johnson L, Sudduth J, May J, Siddiqui AA. Cross-species prophylactic efficacy of Sm-p80-based vaccine and intracellular localization of Sm-p80/Sm-p80 ortholog proteins during development in Schistosoma mansoni, Schistosoma japonicum, and Schistosoma haematobium. Parasitol Res 2017; 116:3175-3188. [PMID: 29026995 PMCID: PMC5660642 DOI: 10.1007/s00436-017-5634-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 09/25/2017] [Indexed: 10/18/2022]
Abstract
Schistosomiasis remains a major global health problem. Despite large-scale schistosomiasis control efforts, clear limitations such as possible emergence of drug resistance and reinfection rates highlight the need for an effective schistosomiasis vaccine. Schistosoma mansoni large subunit of calpain (Sm-p80)-based vaccine formulations have shown remarkable efficacy in protecting against S. mansoni challenge infections in mice and baboons. In this study, we evaluated the cross-species protective efficacy of Sm-p80 vaccine against S. japonicum and S. haematobium challenge infections in rodent models. We also elucidated the expression of Sm-p80 and Sm-p80 ortholog proteins in different developmental stages of S. mansoni, S. haematobium, and S. japonicum. Immunization with Sm-p80 vaccine reduced worm burden by 46.75% against S. japonicum challenge infection in mice. DNA prime/protein boost (1 + 1 dose administered on a single day) resulted in 26.95% reduction in worm burden in S. haematobium-hamster infection/challenge model. A balanced Th1 (IFN-γ, TNF-α, IL-2, and IL-12) and Th2 (IL-4, IgG1) type of responses were observed following vaccination in both S. japonicum and S. haematobium challenge trials and these are associated with the prophylactic efficacy of Sm-p80 vaccine. Immunohistochemistry demonstrated that Sm-p80/Sm-p80 ortholog proteins are expressed in different life cycle stages of the three major human species of schistosomes studied. The data presented in this study reinforce the potential of Sm-p80-based vaccine for both hepatic/intestinal and urogenital schistosomiasis occurring in different geographical areas of the world. Differential expression of Sm-p80/Sm-p80 protein orthologs in different life cycle makes this vaccine potentially useful in targeting different levels of infection, disease, and transmission.
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Affiliation(s)
- Adebayo J Molehin
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Souad R Sennoune
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Weidong Zhang
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Juan U Rojo
- College of Life Sciences and Agriculture, University of New Hampshire, Durham, NH, USA
| | - Arif J Siddiqui
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Karlie A Herrera
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Laura Johnson
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Justin Sudduth
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Jordan May
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Afzal A Siddiqui
- Center for Tropical Medicine and Infectious Diseases, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
- Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
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Wang Q, Da'dara AA, Skelly PJ. The human blood parasite Schistosoma mansoni expresses extracellular tegumental calpains that cleave the blood clotting protein fibronectin. Sci Rep 2017; 7:12912. [PMID: 29018227 PMCID: PMC5635006 DOI: 10.1038/s41598-017-13141-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 09/19/2017] [Indexed: 11/09/2022] Open
Abstract
Schistosomes are intravascular, parasitic flatworms that cause debilitating disease afflicting >200 million people. Proteins expressed at the host-parasite interface likely play key roles in modifying the worm's local environment to ensure parasite survival. Proteomic analysis reveals that two proteases belonging to the calpain family (SmCalp1 and SmCalp2) are expressed in the Schistosoma mansoni tegument. We have cloned both; while highly conserved in domain organization they display just 31% amino acid sequence identity. Both display high relative expression in the parasite's intravascular life forms. Immunolocalization and activity based protein profiling experiments confirm the presence of the enzymes at the host-parasite interface. Living parasites exhibit surface calpain activity that is blocked in the absence of calcium and in the presence of calpain inhibitors (E64c, PD 150606 and calpastatin). While calpains are invariably reported to be exclusively intracellular (except in diseased or injured tissues), our data show that schistosomes display unique, constitutive, functional extracellular calpain activity. Furthermore we show that the worms are capable of cleaving the host blood clotting protein fibronectin and that this activity can be inhibited by E64c. We hypothesize that SmCalp1 and/or SmCalp2 perform this cleavage function to impede blood clot formation around the worms in vivo.
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Affiliation(s)
- Qiang Wang
- Molecular Helminthology Laboratory, Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA, 01536, USA
| | - Akram A Da'dara
- Molecular Helminthology Laboratory, Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA, 01536, USA
| | - Patrick J Skelly
- Molecular Helminthology Laboratory, Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA, 01536, USA.
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Stylianou A, Hadjichrysanthou C, Truscott JE, Anderson RM. Developing a mathematical model for the evaluation of the potential impact of a partially efficacious vaccine on the transmission dynamics of Schistosoma mansoni in human communities. Parasit Vectors 2017; 10:294. [PMID: 28623957 PMCID: PMC5474049 DOI: 10.1186/s13071-017-2227-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 06/01/2017] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND There is currently no vaccine available to protect humans against infection with the schistosome digenean parasites, although candidate formulations for Schistosoma mansoni are under trial in animal models, including rodents and primates. Current strategies for the control of infection are based on mass drug administration (MDA) targeted at school-aged children of age 5 to 14 years. This approach is unlikely to eliminate exposure to infection except in settings with very low levels of transmission. METHODS A deterministic mathematical model for the transmission dynamics of the parasite is described and employed to investigate community level outcomes. The model is defined to encompass two different delivery strategies for the vaccination of the population, namely, infant (cohort) and mass vaccination. However, in this paper the focus is on vaccination delivered in a cohort immunisation programme where infants are immunised within the first year of life before acquiring infection. An analysis of the parasite's transmission dynamics following the administration of a partially protective vaccine is presented. The vaccine acts on parasite mortality, fecundity or/and establishment. RESULTS A vaccine with an efficacy of over 60% can interrupt transmission in low and moderate transmission settings. In higher transmission intensity areas, greater efficacy or higher infant vaccination coverage is required. Candidate vaccines that act either on parasite mortality, fecundity or establishment within the human host, can be similarly effective. In all cases, however, the duration of protection is important. The community level impact of vaccines with all modes of action, declines if vaccine protection is of a very short duration. However, durations of protection of 5-10 years or more are sufficient, with high coverage and efficacy levels, to halt transmission. The time taken to break transmission may be 18 years or more after the start of the cohort vaccination, depending on the intensity of the transmission in a defined location. CONCLUSIONS The analyses provide support for the proposition that even a partially efficacious vaccine could be of great value in reducing the burden of schistosome infections in endemic regions and hopefully could provide a template for the elimination of parasite transmission.
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Affiliation(s)
- Andria Stylianou
- London Centre for Neglected Tropical Disease Research, London, UK
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London, UK
| | - Christoforos Hadjichrysanthou
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London, UK
| | - James E. Truscott
- London Centre for Neglected Tropical Disease Research, London, UK
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London, UK
| | - Roy M. Anderson
- London Centre for Neglected Tropical Disease Research, London, UK
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London, UK
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Hotez PJ, Strych U, Lustigman S, Bottazzi ME. Human anthelminthic vaccines: Rationale and challenges. Vaccine 2016; 34:3549-55. [DOI: 10.1016/j.vaccine.2016.03.112] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 02/23/2016] [Accepted: 03/31/2016] [Indexed: 12/29/2022]
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Molehin AJ, Rojo JU, Siddiqui SZ, Gray SA, Carter D, Siddiqui AA. Development of a schistosomiasis vaccine. Expert Rev Vaccines 2016; 15:619-27. [PMID: 26651503 PMCID: PMC5070536 DOI: 10.1586/14760584.2016.1131127] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Schistosomiasis is a neglected tropical disease (NTD) of public health importance. Despite decades of implementation of mass praziquantel therapy programs and other control measures, schistosomiasis has not been contained and continues to spread to new geographic areas. A schistosomiasis vaccine could play an important role as part of a multifaceted control approach. With regards to vaccine development, many biological bottlenecks still exist: the lack of reliable surrogates of protection in humans; immune interactions in co-infections with other diseases in endemic areas; the potential risk of IgE responses to antigens in endemic populations; and paucity of appropriate vaccine efficacy studies in nonhuman primate models. Research is also needed on the role of modern adjuvants targeting specific parts of the innate immune system to tailor a potent and protective immune response for lead schistosome vaccine candidates with the long-term aim to achieve curative worm reduction. This review summarizes the current status of schistosomiasis vaccine development.
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Affiliation(s)
- Adebayo J. Molehin
- Department of Internal Medicine, Texas Tech University School of Medicine, Lubbock, Texas, USA
- Center of Tropical Medicine and Infectious Diseases, Texas Tech University School of Medicine, Lubbock, Texas, USA
| | - Juan U. Rojo
- Department of Internal Medicine, Texas Tech University School of Medicine, Lubbock, Texas, USA
- Center of Tropical Medicine and Infectious Diseases, Texas Tech University School of Medicine, Lubbock, Texas, USA
| | - Sabrina Z. Siddiqui
- Department of Internal Medicine, Texas Tech University School of Medicine, Lubbock, Texas, USA
- Center of Tropical Medicine and Infectious Diseases, Texas Tech University School of Medicine, Lubbock, Texas, USA
| | | | - Darrick Carter
- PAI Life Sciences, Washington, USA
- Infectious Disease Research Institute, Seattle, Washington, USA
| | - Afzal A. Siddiqui
- Department of Internal Medicine, Texas Tech University School of Medicine, Lubbock, Texas, USA
- Center of Tropical Medicine and Infectious Diseases, Texas Tech University School of Medicine, Lubbock, Texas, USA
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