In a bovine model of onchocerciasis, protective immunity exists naturally, is absent in drug-cured hosts, and is induced by vaccination

Tchakoute, Virginia L, Graham, Simon P., Jensen, Siv Aina, Makepeace, Benjamin L., Nfon, C.K., Njongmeta, L.M., Lustigman, S., Enyong, P. A., Tanya, V. N., Bianco, Albert E. and Trees, Alexander J. (2006) 'In a bovine model of onchocerciasis, protective immunity exists naturally, is absent in drug-cured hosts, and is induced by vaccination'. Proceedings of the National Academy of Sciences of the United States of America, Vol 103, Issue 15, pp. 5971-5976.

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Abstract

Onchocerciasis (river blindness) is a major parasitic disease of humans in sub-Saharan Africa caused by the microfilarial stage of the nematode Onchocerca volvulus. Using Onchocerca ochengi, a closely related species which infects cattle and is transmitted by the same black fly vector (Simulium damnosum sensu lato) as O. volvulus, we have conducted longitudinal studies after either natural field exposure or experimental infection to determine whether, and under what circumstances, protective immunity exists in onchocerciasis. On the basis of the adult worm burdens (nodules) observed, we determined that cattle reared in endemic areas without detectable parasites (putatively immune) were significantly less susceptible to heavy field challenge than age-matched, naive controls (P = 0.002), whereas patently infected cattle, cured of infection by adulticide treatment with melarsomine, were fully susceptible. Cattle immunized with irradiated third-stage larvae were significantly protected against experimental challenge (100% reduction in median nodule load, P = 0.003), and vaccination also conferred resistance to severe and prolonged field challenge (64% reduction in median nodule load, P = 0.053; and a significant reduction in microfilarial positivity rates and density, P < 0.05). These results constitute evidence of protective immunity in a naturally evolved host-Onchocerca sp. relationship and provide proof-of-principle for immunoprophylaxis under experimental and field conditions.

Item Type:	Article
Uncontrolled Keywords:	filariasis irradiation larvae ochengi onchocerca putatively immune volvulus infection litomosoides-sigmodontis gamma-interferon north cameroon ochengi responses parasite larvae identification
Subjects:	QW Microbiology and Immunology > Immunotherapy and Hypersensitivity > QW 805 Vaccines. Antitoxins. Toxoids QW Microbiology and Immunology > Immunotherapy and Hypersensitivity > QW 806 Vaccination WC Communicable Diseases > Tropical and Parasitic Diseases > WC 885 Onchocerciasis
Digital Object Identifer (DOI):	https://doi.org/10.1073/pnas.0601385103
Depositing User:	Sarah Lewis-Newton
Date Deposited:	19 Sep 2011 14:52
Last Modified:	29 Nov 2018 12:24
URI:	https://archive.lstmed.ac.uk/id/eprint/1610

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