title: Experimental infections of rabbits with proliferative and latent stages of Besnoitia besnoiti.
abstract: Cattle besnoitiosis due to Besnoitia besnoiti is spreading across Europe and is responsible for severe economic losses in newly infected herds. Experimentally speaking, rabbits have been found to be susceptible to this parasite. The adaptation of B. besnoiti to rabbits may offer a new, easier and cheaper model of investigation for this disease. This study compared the virulence between tachyzoites and bradyzoites of B. besnoiti in rabbits. Eighteen New Zealand rabbits were allocated into three groups of six animals each. The rabbits from the control (group C), "tachyzoite" (group T) and "bradyzoite" (group B) groups were subcutaneously injected in the right flank with 66 μg of ovalbumin, 6.10(6) tachyzoites (125th passage on Vero cells) and 6.10(6) bradyzoites (collected from a natural infected cow) of B. besnoiti, respectively. Clinical follow-up and blood sampling for serological survey and qPCR were performed during 10 weeks until euthanasia. Molecular and immunohistochemistry examination was achieved on 25 samples of tissue per rabbit. Seroconversion occurred in group T without any clinical signs. Rabbits of group B exhibited a febrile condition (temperature above 40 °C from day 8 to day 11 following injection) with positive qPCR in blood. Cysts of B. besnoiti were found on skin samples and organs of rabbits from group B in tissue explored with threshold cycle (Ct) values below 30. These results suggest a higher virulence of bradyzoites in rabbits than Vero cell-cultivated tachyzoites. The proposed model could be used to assess the in vivo effectiveness of vaccine or drugs against cattle besnoitiosis.
authors.affiliation: UMR INRA/DGER 1225, INP - École Nationale Vétérinaire de Toulouse, Laboratoire de Parasitologie, 23 chemin des Capelles, F-31076, Toulouse, France, e.lienard@envt.fr.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Liénard
authors.forename: Loredana
authors.initials: L
authors.lastname: Pop
authors.forename: Françoise
authors.initials: F
authors.lastname: Prevot
authors.forename: Christelle
authors.initials: C
authors.lastname: Grisez
authors.forename: Virginie
authors.initials: V
authors.lastname: Mallet
authors.forename: Isabelle
authors.initials: I
authors.lastname: Raymond-Letron
authors.forename: Émilie
authors.initials: É
authors.lastname: Bouhsira
authors.forename: Michel
authors.initials: M
authors.lastname: Franc
authors.forename: Philippe
authors.initials: P
authors.lastname: Jacquiet
mesh_terms: D000818:Animals; D002417:Cattle; D002522:Chlorocebus aethiops; D003048:Coccidiosis / Q000469:parasitology / Q000662:veterinary*; D005060:Europe; D005260:Female; D007150:Immunohistochemistry / Q000662:veterinary; D011817:Rabbits / Q000469:parasitology*; D021745:Sarcocystidae / Q000472:pathogenicity* / Q000502:physiology; D014709:Vero Cells; D014774:Virulence