Zhou Huitong, Bennett Grant, Hickford Jon G H
Agriculture and Life Sciences Division, PO Box 84, Lincoln University, Lincoln 7647, New Zealand.
Vet Microbiol. 2009 Mar 30;135(3-4):363-7. doi: 10.1016/j.vetmic.2008.09.084. Epub 2008 Oct 9.
Footrot is a disease of sheep, goats and cattle that causes losses in production and raises welfare issues world-wide. The disease is characterised by destruction of the hard keratin of the hoof leading to lameness, and both Dichelobacter nodosus (D. nodosus) and Fusobacterium necrophorum (F. necrophorum) are thought to be involved in the etiology of this disease. While a lot is known about the genetic diversity of D. nodosus, very little is known about variation in F. necrophorum, especially as regards its role in footrot. We used PCR in conjunction with SSCP and sequencing to analyse swabs collected from the hooves of sheep, goats and cattle with symptomatic footrot for the presence of a portion of the lktA gene of F. necrophorum. Out of 29 samples tested, 27 had amplifiable lktA sequences and within these we found four different variants of the lktA gene. Eight of the nine samples from cattle were positive for a variant that matched the type strain of F. necrophorum subsp. necrophorum. Of the 14 samples from sheep, 13 were positive for lktA, but none of theses matched the known type strains, and 11/13 of the lktA sequences were identical. This sequence was distinct to those of the type strains. None of the footrot infections carried multiple variants of lktA, suggesting that only one strain of F. necrophorum is present in each case. This is in contrast to D. nodosus in footrot infections, which have been demonstrated to have up to seven strains infecting a single hoof.
腐蹄病是一种影响绵羊、山羊和牛的疾病，在全球范围内导致生产损失并引发福利问题。该疾病的特征是蹄部硬角蛋白遭到破坏，进而导致跛行，坏死梭杆菌（F. necrophorum）和坏死厌氧丝杆菌（D. nodosus）都被认为与这种疾病的病因有关。虽然人们对坏死厌氧丝杆菌的遗传多样性了解很多，但对坏死梭杆菌的变异情况却知之甚少，尤其是其在腐蹄病中的作用。我们使用聚合酶链反应（PCR）结合单链构象多态性（SSCP）和测序技术，分析从患有症状性腐蹄病的绵羊、山羊和牛的蹄部采集的拭子，以检测坏死梭杆菌的lktA基因部分序列的存在情况。在测试的29个样本中，27个具有可扩增的lktA序列，在这些样本中我们发现了lktA基因的四种不同变体。来自牛的9个样本中有8个对与坏死梭杆菌亚种坏死梭杆菌模式菌株匹配的变体呈阳性。在来自绵羊的14个样本中，13个lktA呈阳性，但这些样本均与已知模式菌株不匹配，并且13个lktA序列中有11个是相同的。该序列与模式菌株的序列不同。所有腐蹄病感染样本均未携带多个lktA变体，这表明在每种情况下仅存在一种坏死梭杆菌菌株。这与腐蹄病感染中的坏死厌氧丝杆菌形成对比，已证明坏死厌氧丝杆菌感染单个蹄部时最多可有七种菌株。
