title: Acquisition of resistance after continuous infection withAscaridia galliin chickens.
abstract: Acquired resistance againstAscaridia galliinfection was studied in seventy-two 18-week-old white Leghorn chickens allocated to six groups (G1-G6). In order to understand the population dynamics following trickle-infection (100 eggs per chicken twice weekly), chickens of subgroups of G1 were necropsied 3 days after 1, 6 or 12 inoculations (G1A, G1B and G1C respectively), while G2-G4 were inoculated for 6 weeks. G2 was necropsied 4 weeks after the last inoculation. The number of established larvae increased initially (between G1A and G1B) but decreased after repeated inoculations (G1C, G2). G3, G4 and G5 were used to measure the efficacy of anthelminthic treatment and to monitor the acquisition of resistance following a challenge infection. At week 7 G3, G4 and G5 were treated with flubendazole for 7 days in the feed. Two weeks after treatment the chickens in G4 and G5 were challenged with 500 eggs. G6 was left as uninfected control. Necropsy at week 10 after first inoculation revealed a lower establishment rate, an impaired development and a more posterior localization of the larvae in G4 (trickle-infected-treated-challenged) compared with G5 (treated-challenged). IgY level in serum reached noticeable level at 14 dpi in G2 and G4 chickens, and in G4 chickens IgY level further increased after challenge infection. The study provides evidence that acquired resistance againstA. galliin chickens leads to a significant yet incomplete protection against re-infection.
authors.affiliation: Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, DK-1870, Frederiksberg C, Copenhagen, Denmark.
authors.forename: T
authors.initials: T
authors.lastname: Ferdushy
authors.affiliation: DHI, Environment and Toxicology, Agern Alle 5 Hørsholm, Denmark.
authors.forename: T W
authors.initials: TW
authors.lastname: Schou
authors.affiliation: Science and Technology, Department of Animal Science, Aarhus University, Blichers Alle 20, Post Box 50, 8830 Tjele, Denmark.
authors.forename: L R
authors.initials: LR
authors.lastname: Norup
authors.affiliation: Science and Technology, Department of Animal Science, Aarhus University, Blichers Alle 20, Post Box 50, 8830 Tjele, Denmark.
authors.forename: T S
authors.initials: TS
authors.lastname: Dalgaard
authors.affiliation: Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, DK-1870, Frederiksberg C, Copenhagen, Denmark.
authors.forename: S M
authors.initials: SM
authors.lastname: Thamsborg
authors.affiliation: Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, DK-1870, Frederiksberg C, Copenhagen, Denmark.
authors.forename: P
authors.initials: P
authors.lastname: Nejsum
authors.affiliation: DHI, Environment and Toxicology, Agern Alle 5 Hørsholm, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Permin
authors.affiliation: Science and Technology, Department of Animal Science, Aarhus University, Blichers Alle 20, Post Box 50, 8830 Tjele, Denmark.
authors.forename: H R
authors.initials: HR
authors.lastname: Juul-Madsen
authors.affiliation: Section for Production and Health, Department of Large Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Grønnegårdsvej 2, DK-1870, Frederiksberg C, Copenhagen, Denmark.
authors.forename: N C
authors.initials: NC
authors.lastname: Kyvsgaard
keywords: IgY level; Trickle-infection; acquired resistance; anthelminthic treatment