Kleven S H, Fulton R M, García M, Ikuta V N, Leiting V A, Liu T, Ley D H, Opengart K N, Rowland G N, Wallner-Pendleton E
Department of Avian Medicine, University of Georgia, Athens, GA 30602-4875, USA.
Avian Dis. 2004 Sep;48(3):562-9. doi: 10.1637/7148.
Mycoplasma gallisepticum was isolated from several turkey flocks at different locations in the United States that were clinically affected with respiratory disease. Five of these isolates from four series of outbreaks had patterns similar to the 6/85 vaccine strain of M. gallisepticum by random amplified polymorphic DNA (RAPD) analysis using three different primer sets, whereas with a fourth primer set (OPA13 and OPA14), only two of the isolates were similar to 6/85. Results obtained by sequencing portions of the pvpA, gapA, and mgc2 genes and an uncharacterized surface lipoprotein gene indicated that the field isolates had DNA sequences that ranged from 97.6% to 100%, similar to the 6/85 results. In some of the outbreaks there was an indirect association with the presence of commercial layers in the area that had been vaccinated with this vaccine strain, but there was no known close association with vaccinated birds in any of the outbreaks. Turkeys were challenged with two of the field isolates and with 6/85 vaccine strain. Turkeys challenged with the field isolates developed respiratory disease with airsacculitis and a typical M. gallisepticum antibody response, whereas birds challenged with 6/85 developed no respiratory signs or lesions and developed only a weak antibody response. Although these isolates were very similar to the 6/85 vaccine strain, it was not possible to prove that they originated from the vaccine strain-it is possible that they could be naturally occurring field isolates.
从美国不同地点临床感染呼吸道疾病的几个火鸡群中分离出鸡毒支原体。通过使用三种不同引物组的随机扩增多态性DNA（RAPD）分析，从四个系列疫情中的五个分离株具有与鸡毒支原体6/85疫苗株相似的模式，而使用第四种引物组（OPA13和OPA14）时，只有两个分离株与6/85相似。对pvpA、gapA和mgc2基因以及一个未鉴定的表面脂蛋白基因部分进行测序获得的结果表明，现场分离株的DNA序列与6/85的结果相似，范围为97.6%至100%。在一些疫情中，与该地区接种过这种疫苗株的商品蛋鸡的存在存在间接关联，但在任何一次疫情中都没有与接种疫苗的鸟类有已知的密切关联。用火鸡对两个现场分离株和6/85疫苗株进行攻毒。用火鸡现场分离株攻毒的火鸡出现了带有气囊炎的呼吸道疾病和典型的鸡毒支原体抗体反应，而用6/85攻毒的鸟类没有出现呼吸道症状或病变，仅产生了微弱的抗体反应。虽然这些分离株与6/85疫苗株非常相似，但无法证明它们起源于疫苗株——它们有可能是自然存在的现场分离株。
