Rathinam T, Gadde U, Chapman H D
Department of Poultry Science, University of Arkansas, Fayetteville, AR 72701, United States.
Department of Poultry Science, University of Arkansas, Fayetteville, AR 72701, United States.
Vet Parasitol. 2016 Jan 30;216:1-3. doi: 10.1016/j.vetpar.2015.11.014. Epub 2015 Nov 28.
An attenuated line of Eimeria meleagrimitis was established by repeated propagation of the parasite in 9-day old turkey poults and subsequent selection for precocious development. Following 20 passages, the prepatent period decreased from 120 to 104h. A series of experiments were conducted to evaluate the pathogenicity, immunogenicity and fecundity of the newly selected line. Judged by body weight gain, feed consumption and feed efficiency following infection, the attenuated line had appreciably reduced pathogenicity. Immunogenicity of the attenuated line was examined by infecting poults successively with incremental doses of 10(2), 10(3) and 10(4) oocysts at 0, 7, and 14 days of age respectively. No oocysts were detected following challenge with 5×10(2) oocysts, indicating that the attenuated line had retained immunogenicity. Fecundity was assessed by infecting two-week old birds with 5×10(2) oocysts of either parent or attenuated line. Oocyst production from 96 to 240h post-infection showed that the patent period of the attenuated line commenced earlier and was of shorter duration than the parent line.
通过在9日龄火鸡雏中反复传代寄生虫并随后选择早熟发育，建立了一种柔嫩艾美耳球虫减毒株。经过20代传代后，潜隐期从120小时缩短至104小时。进行了一系列实验以评估新选择品系的致病性、免疫原性和繁殖力。从感染后的体重增加、采食量和饲料效率判断，减毒株的致病性明显降低。通过分别在0、7和14日龄用递增剂量的10²、10³和10⁴个卵囊连续感染雏鸡来检测减毒株的免疫原性。用5×10²个卵囊攻击后未检测到卵囊，表明减毒株保留了免疫原性。通过用亲本或减毒株的5×10²个卵囊感染两周龄的鸡来评估繁殖力。感染后96至240小时的卵囊产生情况表明，减毒株的排虫期开始得更早，持续时间比亲本品系短。
