Department of Microbiology, National Veterinary Institute, Uppsala, Sweden.
Department of Animal Health and Antimicrobial Strategies, National Veterinary Institute, Uppsala, Sweden.
BMC Vet Res. 2021 Mar 6;17(1):111. doi: 10.1186/s12917-021-02813-0.
Erysipelas, caused by Erysipelothrix rhusiopathiae (ER), is an important emerging disease in free-range and organic egg-production. The aim of the present study was to assess if quantification of ER specific IgY titers may aid the understanding of erysipelas in commercial laying hens. The methodology was validated with sequentially collected sera from experimentally ER infected SPF-chickens and subsequently applied on sera from Swedish commercial laying hens collected during and after outbreaks of erysipelas or collected at slaughter from healthy hens housed in furnished cages, barn production or in organic production (with outdoor access).
In experimentally infected SPF-chickens, titers to ER were significantly increased approximately one week after infection while IgY to ER in uninfected age-matched controls remained low. Also chickens infected with low doses of ER, not displaying clinical signs of disease and with low recovery of ER in blood samples showed high titers of IgY to ER. For laying hens during and after erysipelas outbreaks the majority of samples were considered positive for antibodies to ER with a large variation in levels of IgY titers to ER between individuals. For healthy laying hens at slaughter all samples were deemed positive for antibodies to ER. An influence of flock on levels of IgY titers to ER was observed for both healthy hens and hens during erysipelas outbreaks. For healthy laying hens at slaughter no influence of the housing systems included in the study, history of erysipelas outbreaks at the farm or vaccination on levels of IgY titers to ER was noticed.
Taken together, these results show that high numbers of commercial laying hens showed high IgY titers to ER, comparable to those elicited by experimental ER infection, indicating that ER or bacteria that raises antibodies that cross-react with ER are common in this environment.
红斑丹毒丝菌（ER）引起的丹毒是自由放养和有机蛋鸡生产中一种重要的新兴疾病。本研究旨在评估 ER 特异性 IgY 滴度的定量是否有助于了解商业产蛋鸡中的丹毒。该方法用 ER 感染的 SPF 鸡连续采集的血清进行了验证，随后应用于瑞典商业产蛋鸡在丹毒爆发期间和之后采集的血清，或从饲养在有家具的笼子、谷仓生产或有机生产（有户外活动）中健康母鸡屠宰时采集的血清。
在实验性感染的 SPF 鸡中，ER 滴度在感染后约一周显著增加，而未感染的同龄对照鸡的 ER 特异性 IgY 仍保持低水平。同样，感染低剂量 ER 且不显示疾病临床症状且血液样本中 ER 回收率低的鸡也表现出对 ER 的高滴度 IgY。对于丹毒爆发期间和之后的产蛋鸡，大多数样本被认为对 ER 抗体呈阳性，个体之间 ER 特异性 IgY 滴度水平存在很大差异。对于屠宰时的健康产蛋鸡，所有样本均被认为对 ER 抗体呈阳性。在健康母鸡和丹毒爆发期间的母鸡中，均观察到鸡群对 ER 特异性 IgY 滴度水平有影响。对于屠宰时的健康产蛋鸡，未发现研究中包含的饲养系统、农场的丹毒爆发史或疫苗接种对 ER 特异性 IgY 滴度水平有影响。
总之，这些结果表明，大量商业产蛋鸡表现出高数量的 ER 特异性 IgY，与实验性 ER 感染引起的数量相当，这表明 ER 或与 ER 发生交叉反应的细菌在这种环境中很常见。
