Moraxella ovis is a Gram-negative bacterium isolated from sheep conjunctivitis cases and is a rare isolate of infectious bovine keratoconjunctivitis (IBK). This species is closely related to M. bovoculi, another species which can also be isolated from IBK, or cattle upper respiratory tract (URT). Prior to molecular identification techniques, M. bovoculi was frequently misclassified as M. ovis. We previously described the structure of two oligosaccharides (lipooligosaccharide-derived, minor and major glycoforms) from M. bovoculi 237T (type strain, also ATCC BAA-1259T). Here, we have identified the genetic loci for lipooligosaccharide synthesis in M. ovis 354T (NCTC11227) and compared it with M. bovoculi 237T. We identified genes encoding the known glycosyltransferases Lgt6 and Lgt3 in M. ovis. These genes are conserved in Moraxella spp., including M bovoculi. We identified three further putative OS biosynthesis genes that are restricted to M. ovis and M. bovoculi. These encode enzymes predicted to function as GDP-mannose synthases, namely a mannosyltransferase and a glycosyltransferase. Adding insight into the genetic relatedness of M. ovis and M. bovoculi, the M. ovis genes have higher similarity to those in M. bovoculi genotype 2 (nasopharyngeal isolates from asymptomatic cattle), than to M. bovoculi genotype 1 (isolates from eyes of IBK-affected cattle). Sequence analysis confirmed that the predicted mannosyltransferase in M. bovoculi 237T is interrupted by a C>T polymorphism. This mutation is not present in other M. bovoculi strains sequenced to date.

We isolated and characterised LOS-derived oligosaccharide from M. ovis 354T. GLC-MS and NMR spectroscopy data revealed a heptasaccharide structure with three β-D-Glcp residues attached as branches to the central 3,4,6-α-D-Glcp, with subsequent attachment to Kdo. This inner core arrangement is consistent with the action of Lgt6 and Lgt3 glycosyltransferases. Two α-D-Manp residues are linearly attached to the 4-linked β-D-Glcp, consistent with the presence of the two identified glycosyltransferases. This oligosaccharide structure is consistent with the previously reported minor glycoform isolated from M. bovoculi 237T.

绵羊莫拉氏菌是一种从绵羊结膜炎病例中分离出来的革兰氏阴性细菌，也是传染性牛角结膜炎 (IBK) 的罕见分离株。该物种与M. bovoculi密切相关，后者也可以从 IBK 或牛上呼吸道 (URT) 中分离出来。在分子鉴定技术出现之前，牛分枝杆菌经常被错误分类为绵羊分枝杆菌。我们之前描述了来自M. bovoculi 237T（典型菌株，也为 ATCC BAA-1259T）的两种寡糖（脂寡糖衍生的次要糖型和主要糖型）的结构。在这里，我们鉴定了绵羊小羊354T (NCTC11227) 中脂寡糖合成的遗传位点，并将其与牛小羊237T 进行了比较。我们鉴定了绵羊绵羊中编码已知糖基转移酶 Lgt6 和 Lgt3 的基因。这些基因在莫拉氏菌属中保守，包括牛氏莫拉氏菌。我们进一步鉴定了三个假定的 OS 生物合成基因，这些基因仅限于绵羊小球菌和牛小球藻。这些编码酶预计将起到GDP-甘露糖合酶的作用，即甘露糖基转移酶和糖基转移酶。进一步了解绵羊支原体和牛支原体的遗传相关性，绵羊支原体基因与牛支原体基因型 2（从无症状牛的鼻咽分离株）中的相似性高于与牛支原体基因型 1（从眼睛中分离株）的相似性受 IBK 影响的牛）。序列分析证实了M.中预测的甘露糖基转移酶。 bovoculi 237T 被 C>T 多态性中断。这种突变在迄今为止测序的其他牛分枝杆菌菌株中不存在。

我们从M. ovis 354T 中分离并表征了 LOS 衍生的寡糖。 GLC-MS 和 NMR 波谱数据揭示了七糖结构，其中三个 β-D-Glc p残基作为分支连接到中心 3,4,6-α-D-Glc p，随后连接到 Kdo。这种内核排列与 Lgt6 和 Lgt3 糖基转移酶的作用一致。两个 α-D-Man p残基线性连接到 4 连接的 β-D-Glc p上，这与两种已鉴定的糖基转移酶的存在一致。该寡糖结构与先前报道的从M. bovoculi 237T 分离的次要糖型一致。