Evaluation of the host specificity of Eimeria uekii and Eimeria raichoi for Japanese rock ptarmigans by oocyst transfer to taxonomically related birds

Experimental evaluation of pathogenicity and acquired immunity of Eimeria species, E. uekii and E. raichoi, infecting Japanese rock ptarmigans in a subspecies of the birds

“…Immunohistochemical examinations were conducted to confirm the parasites, as previously reported ( Iwanaga et al, 2022 ; Matsubayashi et al, 2023 ). Briefly, paraffin-embedded sections of the tissues were incubated with 3% hydrogen peroxide, and antigen was retrieved using 0.1% actinase E solution in PBS.…”

“…The inoculation doses of E. uekii were 4 × 10 4 (for 5 birds), 2 × 10 4 (for 3 birds), 4 × 10 3 (for 4 birds), and 4 × 10 2 (for 4 birds), which contained 1.7 × 10 4 to 2 × 10 1 oocysts of E. raichoi ( Table 1 ). Additionally, two Svalbard rock ptarmigans were inoculated with 4 × 10 4 E. raichoi oocysts that had been passaged in turkeys and purified using the same method ( Matsubayashi et al, 2023 ). As a control, 4 birds were orally administered the same volume of PBS.…”

“…In our previous study, we experimentally evaluated the infectivity of parasites derived from Japanese rock ptarmigans using other bird species. We found that E. uekii failed to infect any of the examined birds, including chickens, and E. raichoi could be successfully cross-transmitted only to turkeys, without any clinical symptoms ( Matsubayashi et al, 2023 ). Thus, in the present study, the infectivity of the parasites was assessed using Svalbard rock ptarmigans ( Lagopus mutus hyperboreus ) as a subspecies of Japanese rock ptarmigans, and the virulence of the parasites was analyzed using a more closely related animal model in the same genus.…”