A murine macrofilaricide pre-clinical screening model for onchocerciasis and lymphatic filariasis

Halliday, Alice, Guimaraes, Ana, Tyrer, Hayley, Metuge, Haelly, Patrick, Chounna, Arnaud, Kengne-Ouafo, Kwenti, Tayong, Forsbrook, George, Steven, Andrew, Cook, Darren, Enyong, Peter, Wanji, Samuel, Taylor, Mark ORCID: https://orcid.org/0000-0003-3396-9275 and Turner, Joseph ORCID: https://orcid.org/0000-0002-2185-5476 (2014) 'A murine macrofilaricide pre-clinical screening model for onchocerciasis and lymphatic filariasis'. Parasites & Vectors, Vol 7, e472.

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Abstract

Background

New drugs effective against adult filariae (macrofilaricides) would accelerate the elimination of lymphatic filariasis and onchocerciasis. Anti-Onchocerca drug development is hampered by the lack of a facile model. We postulated that SCID mice could be developed as a fmacrofilaricide screening model.

Methods

The filaricides: albendazole (ABZ), diethylcarbamazine (DEC), flubendazole (FBZ), ivermectin (IVM) and the anti-Wolbachia macrofilaricide, minocycline (MIN) were tested in Brugia malayi (Bm)-parasitized BALB/c SCID mice vs vehicle control (VC). Responses were compared to BALB/c wild type (WT). Onchocerca ochengi male worms or onchocercomata were surgically implanted into BALB/c SCID, CB.17 SCID, BALB/c WT mice or Meriones gerbils. Survival was evaluated at 7¿15 days. BALB/c SCID were tested to evaluate the responsiveness of pre-clinical macrofilaricides FBZ and rifapentine (RIFAP) against male Onchocerca.

Results

WT and SCID responded with >95% efficacy following ABZ or DEC treatments against Bm larvae (P < 0.0001). IVM was partially filaricidal against Bm larvae in WT and SCID (WT; 39.8%, P = 0.0356 and SCID; 56.7%, P = 0.026). SCID responded similarly to WT following IVM treatment of microfilaraemias (WT; 79%, P = 0.0194. SCID; 76%, P = 0.0473). FBZ induced a total macrofilaricidal response against adult Bm in WT and SCID (WT; P = 0.0067, SCID; P = 0.0071). MIN induced a >90% reduction in Bm Wolbachia burdens (P < 0.0001) and a blockade of microfilarial release (P = 0.0215) in SCID. Male Onchocerca survival was significantly higher in SCID vs WT mice, but not gerbils, after +15 days (60% vs 22% vs 39% P = 0.0475). Onchocercoma implants had engrafted into host tissues, with evidence of neovascularisation, after +7 days and yielded viable macro/microfilariae ex vivo. FBZ induced a macrofilaricidal effect in Onchocerca male implanted SCID at +5 weeks (FBZ; 1.67% vs VC; 43.81%, P = 0.0089). Wolbachia loads within male Onchocerca were reduced by 99% in implanted SCID receiving RIFAP for +2 weeks.

Conclusions

We have developed a `pan-filarial¿ small animal research model that is sufficiently robust, with adequate capacity and throughput, to screen existing and future pre-clinical candidate macrofilaricides. Pilot data suggests a murine onchocercoma xenograft model is achievable.

Item Type:	Article
Subjects:	QV Pharmacology > Drug Standardization. Pharmacognosy. Medicinal Plants > QV 771 Standardization and evaluation of drugs WC Communicable Diseases > Tropical and Parasitic Diseases > WC 880 Filariasis and related conditions (General) WC Communicable Diseases > Tropical and Parasitic Diseases > WC 885 Onchocerciasis
Faculty: Department:	Biological Sciences > Department of Tropical Disease Biology
Digital Object Identifer (DOI):	https://doi.org/10.1186/s13071-014-0472-z
Depositing User:	Mary Creegan
Date Deposited:	07 Nov 2014 11:03
Last Modified:	17 Jul 2020 10:59
URI:	https://archive.lstmed.ac.uk/id/eprint/4530

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