The Tengmalm's owl(Aves, Strigidae) as the definitive host ofsp. nov. (Apicomplexa).

Abstract

BACKGROUND: Owls have been reported as definitive hosts, whereas wild small mammals (naturally and experimentally) as intermediate hosts of several species of. Recently, dead fledglings were found infected by an unnamed species ofsince its intermediate host was unknown. After collecting additional samples of owls and wild small mammals, the present study focused on elucidating the identity, potential intermediate host, and complete life cycle of the foundthrough experimentally infected rodents. The developmental stages' morphological and molecular characterizations (rRNA gene, ITS1 region) are presented herein. METHODS: In total, 21 Tengmalm's owl carcasses (15 nestlings, 5 fledglings, and 1 adult male) were collected in Kauhava (west-central Finland) and parasitologically examined by wet mounts. Intestinal mucosa scrapings were used to isolate oocysts/sporocysts and employed for experimental infections in dexamethasone-immunosuppressed BALB/cOlaHsd mice. Additionally, sarcocysts were searched in the skeletal muscle of 95 samples from seven wild small mammal species. All these developmental stages were molecularly characterized by therRNA gene and ITS1 region. Experimental infections were carried out by using immunosuppressed female 8-week-old BALB/cOlaHsd mice, divided into three groups: (1) water with 15 μg/mL of dexamethasone, (2) water with 30 μg/mL of dexamethasone, (3) no dexamethasone treatment. Each group consisted of four individuals. In each group, two mice were infected with 1,000 sporocysts each, and the remaining two with 10,000 sporocysts each. All mice were euthanized on specific days post-infection. RESULTS: The intestinal mucosa of 11 nestlings and 5 fledglings of the Tengmalm's owl were positive forsp. nov. The adult male owl and all owls' breast and heart muscles were negative for. Two dexamethasone-immunosuppressed BALB/cOlaHsd mice (group 2) were positive tosp. nov. in diaphragm and leg muscles after 22- and 24-day post-infection. Some sarcocysts were found in the wild small mammals. Molecular identification atrRNA revealed sequences from naturally infected Tengmalm's owls, as well as sarcocysts of dexamethasone-immunosuppressed BALB/cOlaHsd mice were 99.87-100% similar tosp. isolate Af1 previously found in the Tengmalm's owl. At the ITS1 region, thesp. nov. isolates Af2 haplotype B and Af3 haplotype A were 98.77-100% identical tosp. isolate Af1. The sequences from sarcocysts of naturally infected wild small mammals were 75.23-90.30% similar at ITS1 region to those ofsp. nov. CONCLUSION: The morphological and molecular characterizations and phylogenetic placement ofsp. nov. are presented here for the first time and support the erection of the new species.