Mycoplasma gallisepticum, a significant poultry pathogen, has evolved rapidly in its new passerine host since its first reported isolation from house finches in the US in 1994. In poultry, M. gallisepticum infects the upper respiratory tract, causing tracheal mucosal thickening and inflammation, in addition to inflammation of the reproductive tract. However, in house finches M. gallisepticum primarily causes inflammation of the conjunctiva. Given that different tissues are primarily affected by the same pathogen in different hosts, we have compared the early changes in gene expression of the phase-variable lipoproteins (vlhA) gene family of M. gallisepticum collected directly from target tissues in both hosts. Previous data have demonstrated that vlhA genes may be related to virulence, exhibiting changes in expression in a non-stochastic, temporal progression and we hypothesize that this may be influenced by differences in the target host tissue. If this is true, we would expect M. gallisepticum to display a different vlhA gene expression pattern in the chicken trachea compared to its expression pattern in house finch conjunctiva.

Here we report significant differences in vlhA gene expression patterns between M. gallisepticum collected from chicken tracheas compared to those collected from house finch conjunctiva. While many of the predominant vlhA genes expressed in the input population showed an increase in expression in the chicken trachea at day one postinfection, those same vlhA genes decreased in expression in the house finch. These data suggest that discrete suites of vlhA genes may be involved in M. gallisepticum pathogenesis and tropism for unique tissues in two disparate avian hosts.

自1994年美国首次报道从雀科鸟类中分离出鸡冠状支原体以来，鸡支原体是一种重要的家禽病原体，其发展迅速。在家禽中，鸡支原体支原体感染上呼吸道，引起气管粘膜增厚和炎症。除了生殖道发炎。然而，在室内雀科中，鸡败血支原体主要引起结膜发炎。鉴于不同的组织主要受不同宿主中同一病原体的影响，我们比较了鸡毒支原体的相变脂蛋白（vlhA）基因家族的基因表达的早期变化。直接从两个宿主的靶组织中收集。先前的数据已证明vlhA基因可能与毒力有关，在非随机，暂时性进程中表现出表达变化，我们推测这可能受靶宿主组织差异的影响。如果真是这样，我们希望鸡败血支原体在鸡气管中显示出与其室内雀科结膜中不同的vlhA基因表达模式。

在这里我们报告从鸡气管收集的鸡毒支原体与从室内雀科结膜收集的鸡支气管炎支原体之间的vlhA基因表达模式有显着差异。尽管在输入群体中表达的许多主要vlhA基因在感染后第一天在鸡气管中表达增加，但是那些相同的vlhA基因在家禽中表达却下降了。这些数据表明vlhA基因的离散套件可能参与了两个分离的禽类宿主中鸡毒支原体的发病机制和向性性。