title: Experimental inhibition of nitric oxide increases Plasmodium relictum (lineage SGS1) parasitaemia.
abstract: Malaria is a widespread vector-borne disease infecting a wide range of terrestrial vertebrates including reptiles, birds and mammals. In addition to being one of the most deadly infectious diseases for humans, malaria is a threat to wildlife. The host immune system represents the main defence against malaria parasites. Identifying the immune effectors involved in malaria resistance has therefore become a major focus of research. However, this has mostly involved humans and animal models (rodents) and how the immune system regulates malaria progression in non-model organisms has been largely ignored. The aim of the present study was to investigate the role of nitric oxide (NO) as an immune effector contributing to the control of the acute phase of infection with the avian malaria agent Plasmodium relictum. We used experimental infections of domestic canaries in conjunction with the inhibition of the enzyme inducible nitric oxide synthase (iNOS) to assess the protective function of NO during the infection, and the physiological costs paid by the host in the absence of an effective NO response. Our results show that birds treated with the iNOS inhibitor suffered from a higher parasitaemia, but did not pay a higher cost of infection (anaemia). While these findings confirm that NO contributes to the resistance to avian malaria during the acute phase of the infection, they also suggest that parasitaemia and costs of infection can be decoupled.
authors.affiliation: BioGéosciences, UMR CNRS 5561, Université de Bourgogne, 6 Boulevard Gabriel, 21000 Dijon, France. coraline.bichet@u-bourgogne.fr
authors.forename: Coraline
authors.initials: C
authors.lastname: Bichet
authors.forename: Stéphane
authors.initials: S
authors.lastname: Cornet
authors.forename: Stephen
authors.initials: S
authors.lastname: Larcombe
authors.forename: Gabriele
authors.initials: G
authors.lastname: Sorci
mesh_terms: D000818:Animals; D002171:Canaries / Q000469:parasitology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006146:Guanidines / Q000494:pharmacology; D008289:Malaria, Avian / Q000097:blood / Q000276:immunology / Q000378:metabolism*; D009569:Nitric Oxide / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors; D018512:Parasitemia / Q000276:immunology / Q000378:metabolism* / Q000469:parasitology; D010961:Plasmodium / Q000276:immunology / Q000378:metabolism; D046370:Sparrows / Q000469:parasitology*
chemical_list: D004791:Enzyme Inhibitors; D006146:Guanidines; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; C004479:pimagedine