A Chicken Embryo Lethality Assay for Pathogenic Enterococcus cecorum
A Chicken Embryo Lethality Assay for Pathogenic Enterococcus cecorum
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DOI：
10.1637/10687-101113-reg.1
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发表时间：
2014-06-01
期刊：
影响因子：
1.4
通讯作者：
Barnes, H. John
中科院分区：
文献类型：
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作者：
Borst, Luke B.;Suyemoto, M. Mitsu;Barnes, H. John
盲肠肠球菌的致病性菌株在世界范围内引起鸡关节炎和骨髓炎的暴发。肠球菌性脊柱炎（Enterococcal spondylitis，ES）是肠球菌性脊柱炎的一种特殊表现。肉鸡和肉鸡育种者的盲肠相关疾病，其特征为群死亡率增加，由致病性E.盲肠。一项对美国东南部22起ES暴发的研究表明，致病性E。从脊柱病变分离的盲肠菌菌株是遗传克隆的。在这里，我们比较了以前的基因型致病菌株（n = 8）分离脊髓病变和非致病菌株（n = 9）从盲肠未受影响的鸟类在鸡胚致死模型的毒力。将菌株接种到12日龄肉仔鸡和无特定病原体（SPF）蛋鸡胚胎的尿囊腔中;通过每天对鸡蛋进行4天的检查来确定胚胎存活率。与接种非致病基因型菌株的胚胎相比，接种致病基因型菌株的肉鸡和SPF胚胎的存活率显著降低（肉鸡胚胎，23%对60%; SPF胚胎，9%对61%）。感染致病菌株的胚胎无法控制感染，并始终显示败血症典型的肉眼变化，包括出血和水肿。48小时后，在感染非致病性菌株的胚胎中未观察到类似的变化。该胚胎致死性试验为了解大肠杆菌的遗传基础提供了有用的工具。盲肠毒力
Pathogenic strains of Enterococcus cecorum cause outbreaks of arthritis and osteomyelitis in chickens worldwide. Enterococcal spondylitis (ES) is a specific manifestation of E. cecorum-associated disease of broilers and broiler breeders characterized by increased flock mortality, resulting from unresolved infection of the free thoracic vertebra by pathogenic E. cecorum. A study of 22 ES outbreaks in the southeast United States revealed that pathogenic E. cecorum strains isolated from spinal lesions were genetically clonal. Here, we compare the virulence of previously genotyped pathogenic strains (n = 8) isolated from spinal lesions and nonpathogenic strains (n = 9) isolated from ceca of unaffected birds in a chicken embryo lethality model. Strains were inoculated into the allantoic cavity of 12-day-old broiler and specific-pathogen-free (SPF) layer embryos; embryo survival was determined by candling eggs daily for 4 days. Significantly decreased survival occurred in both broiler and SPF embryos inoculated with pathogenic genotype strains compared with embryos inoculated with nonpathogenic genotype strains (broiler embryos, 23% vs. 60%; SPF embryos, 9% vs. 61%). Embryos infected with pathogenic strains were unable to control infection and consistently showed gross changes typical of sepsis, including hemorrhage and edema. After 48 hr, similar changes were not observed in embryos infected with nonpathogenic strains. This embryo lethality assay provides a useful tool for understanding the genetic basis of E. cecorum virulence.