Abdel Jelil Njouendou1, Chi Anizette Kien2, Mathias E Esum3, Manuel Ritter4, Winston Patrick Chounna Ndongmo5, Fanny Fri Fombad6, Narcisse Victor T Gandjui7, Flobert Njiokou8, Peter Enyong9, Kenneth Pfarr10, Joseph Turner11, Laura E Layland12, Achim Hoerauf13, Samuel Wanji14. 1. Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Department of Biomedical Sciences, Faculty of Health Sciences, University of Buea, Buea, Cameroon. Electronic address: ajnjouendou@gmail.com. 2. Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon. Electronic address: kienchi91.kc@gmail.com. 3. Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon. Electronic address: mathias_mesum@yahoo.fr. 4. Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany. Electronic address: Manuel.Ritter@ukbonn.de. 5. Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon. Electronic address: ndongmopatrick1@gmail.com. 6. Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Department of Zoology and Animal Physiology, Faculty of Science, University of Buea, Buea, Cameroon. Electronic address: fffombad@gmail.com. 7. Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon. Electronic address: gvictornarcisse@yahoo.com. 8. Department of Animal Biology and Physiology, Faculty of Science, University of Yaounde I, Yaounde, Cameroon. Electronic address: njiokouf@yahoo.com. 9. Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon. Electronic address: enyongap@gmail.com. 10. Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany; German Center for Infection Research (DZIF), Bonn - Cologne Partner Site, Bonn, Germany. Electronic address: kenneth.pfarr@ukbonn.de. 11. Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, UK. Electronic address: Joseph.Turner@lstmed.ac.uk. 12. Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany; German Center for Infection Research (DZIF), Bonn - Cologne Partner Site, Bonn, Germany. Electronic address: laura.layland@sbcomputing.de. 13. Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany; German Center for Infection Research (DZIF), Bonn - Cologne Partner Site, Bonn, Germany. Electronic address: hoerauf@uni-bonn.de. 14. Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon. Electronic address: swanji@yahoo.fr.
Abstract
BACKGROUND: Mansonellosis arises from infections with threadlike filarial nematodes in millions of individuals, especially in sub-Saharan Africa. Since infections present no overt clinical symptoms but attenuate immune responses that might lead to increased susceptibility and worsened disease course of concomitant infections, it is truly a neglected tropical disease. Nevertheless, only few studies focus on identifying suitable safe drugs for its control and little is known about the requirements for in vitro maintenance of the Mansonella perstans transmission stage. This study, therefore, evaluated the survival of M. perstans microfilariae (mf) using in vitro conditions that have been shown to promote survival of Loa loa, a closely related filarial nematode. Furthermore, the in vitro microfilaricidal effect of 15 agents was assessed on this helminth. METHODS: The ability of two basic culture media; Dulbecco's Modified Eagle's Medium (DMEM) and Roswell Park Memorial Institute (RPMI-1640) supplemented with 10% fetal bovine serum (FBS) and a monkey kidney epithelial cell line (LLC-MK2) to support the survival of M. perstans microfilariae was investigated. Subsequently, 6 anti-helminthics, 5 anti-malarials, 1 anti-microbacterial, 2 trypanocidals and 1 anti-cancer agent were tested in vitro against mf. The suitability of the culture media as well as the effect of the anti-infective agents on mf survival was assessed by scoring their motility. RESULTS: FBS supplement and additional LLC-MK2 cells significantly improved the survival of mf in DMEM and RPMI-1640 culture. In detail, RPMI-1640 supplemented with 10% FBS and LLC-MK2 cells sustained the maintenance of mf for at least 20 days (100.00 ± 0.00% survival). In co-cultures with LLC-MK2 cells without serum, M. perstans mf were maintained in DMEM and RPMI-1640 medium with a motility above 99% by day 5. Mefloquine displayed the highest microfilaricidal effect in vitro followed by artesunate. CONCLUSION: Both RPMI and DMEM in the presence of LLC-MK2 cells are suitable for the maintenance of M. perstans mf in vitro. In absence of the feeder cells, the addition of 10% FBS to RPMI-1640 medium improved the parasite survival rate and motility. The microfilaricidal activity of mefloquine and artesunate on M. perstans mf was documented for the first time in this study and can therefore be considered as reference for further screening of agents against this parasite stage.
BACKGROUND: Mansonellosis arises from infections with threadlike filarial nematodes in millions of individuals, especially in sub-Saharan Africa. Since infections present no overt clinical symptoms but attenuate immune responses that might lead to increased susceptibility and worsened disease course of concomitant infections, it is truly a neglected tropical disease. Nevertheless, only few studies focus on identifying suitable safe drugs for its control and little is known about the requirements for in vitro maintenance of the Mansonella perstans transmission stage. This study, therefore, evaluated the survival of M. perstans microfilariae (mf) using in vitro conditions that have been shown to promote survival of Loa loa, a closely related filarial nematode. Furthermore, the in vitro microfilaricidal effect of 15 agents was assessed on this helminth. METHODS: The ability of two basic culture media; Dulbecco's Modified Eagle's Medium (DMEM) and Roswell Park Memorial Institute (RPMI-1640) supplemented with 10% fetal bovine serum (FBS) and a monkey kidney epithelial cell line (LLC-MK2) to support the survival of M. perstans microfilariae was investigated. Subsequently, 6 anti-helminthics, 5 anti-malarials, 1 anti-microbacterial, 2 trypanocidals and 1 anti-cancer agent were tested in vitro against mf. The suitability of the culture media as well as the effect of the anti-infective agents on mf survival was assessed by scoring their motility. RESULTS: FBS supplement and additional LLC-MK2 cells significantly improved the survival of mf in DMEM and RPMI-1640 culture. In detail, RPMI-1640 supplemented with 10% FBS and LLC-MK2 cells sustained the maintenance of mf for at least 20 days (100.00 ± 0.00% survival). In co-cultures with LLC-MK2 cells without serum, M. perstans mf were maintained in DMEM and RPMI-1640 medium with a motility above 99% by day 5. Mefloquine displayed the highest microfilaricidal effect in vitro followed by artesunate. CONCLUSION: Both RPMI and DMEM in the presence of LLC-MK2 cells are suitable for the maintenance of M. perstans mf in vitro. In absence of the feeder cells, the addition of 10% FBS to RPMI-1640 medium improved the parasite survival rate and motility. The microfilaricidal activity of mefloquine and artesunate on M. perstans mf was documented for the first time in this study and can therefore be considered as reference for further screening of agents against this parasite stage.
Authors: Amy E Marriott; Julio Furlong Silva; Nicolas Pionnier; Hanna Sjoberg; John Archer; Andrew Steven; Dale Kempf; Mark J Taylor; Joseph D Turner Journal: PLoS Negl Trop Dis Date: 2022-06-07
Authors: Narcisse V T Gandjui; Abdel J Njouendou; Eric N Gemeg; Fanny F Fombad; Manuel Ritter; Chi A Kien; Valerine C Chunda; Jerome Fru; Mathias E Esum; Marc P Hübner; Peter A Enyong; Achim Hoerauf; Samuel Wanji Journal: PLoS Negl Trop Dis Date: 2021-02-09
Authors: Anna Wiszniewsky; Laura E Layland; Kathrin Arndts; Lisa M Wadephul; Ruth S E Tamadaho; Dennis Borrero-Wolff; Valerine C Chunda; Chi Anizette Kien; Achim Hoerauf; Samuel Wanji; Manuel Ritter Journal: Front Immunol Date: 2021-11-18 Impact factor: 7.561
Authors: Abdel Jelil Njouendou; Manuel Ritter; Chi Anizette Kien; Mathias E Esum; Winston Patrick Chounna Ndongmo; Fanny Fri Fombad; Narcisse Victor T Gandjui; Flobert Njiokou; Peter Enyong; Kenneth Pfarr; Joseph Turner; Laura E Layland; Achim Hoerauf; Samuel Wanji Journal: Data Brief Date: 2019-12-04