Niang Mamadou, Diallo Mahamadou, Cisse Ousmane, Kone Mamadou, Doucoure Modibo, Roth James A, Balcer-Rodrigues Valérie, Dedieu Laurence
Laboratoire Central Vétérinaire, Km 8, route de Koulikoro, BP 2295, Bamako, Mali.
Vet Res. 2006 Sep-Oct;37(5):733-44. doi: 10.1051/vetres:2006032. Epub 2006 Jul 6.
The purpose of the present study was to characterize the Mycoplasma mycoides subsp. mycoides small colony (MmmSC)-specific humoral immune response at both systemic and local levels in cattle experimentally infected with MmmSC, for a better understanding of the protective immune mechanisms against the disease. The disease was experimentally reproduced in zebu cattle by contact. Clinical signs, postmortem and microbiological findings were used to evaluate the degree of infection. Serum and bronchial lavage fluids (BAL) were collected sequentially, before contact and over a period of one year after contact. The kinetics of the different antibody isotypes to MmmSC was established. Based on the severity of the clinical signs, post mortem and microbiological findings, the animals were classified into three groups as acute form with deaths, sub-acute to chronic form and resistant animals. Seroconversion was never observed for the control animals throughout the duration of the experiment, nor for those classified as resistant. Instead, seroconversion was measured for all other cattle either with acute or sub-acute to chronic forms of the disease. For these animals, IgM, IgG1, IgG2 and IgA responses were detected in the serum and BAL samples. The kinetics of the IgM, IgG1 and IgG2 responses was nearly similar between both groups of animals. No evident correlation could thus be established between the levels of these isotypes and the severity of the disease. Levels of IgA were high in both BAL and serum samples of animals with sub-acute to chronic forms of the disease, and tended to persist throughout the entire experimental period. In contrast, animals with acute forms of the disease showed low levels of IgA in their BAL samples with none or very transient but low levels of IgA in the serum samples. Our results thus demonstrated that IgA is produced locally in MmmSC experimentally infected cattle by contact and may play a role in protection against contagious bovine pleuropneumonia.
本研究的目的是在实验性感染丝状支原体丝状亚种小菌落型（MmmSC）的牛中，从全身和局部水平表征其特异性体液免疫反应，以便更好地了解针对该疾病的保护性免疫机制。通过接触在瘤牛中实验性再现该疾病。利用临床症状、死后剖检和微生物学检查结果评估感染程度。在接触前以及接触后的一年时间内，依次采集血清和支气管灌洗液（BAL）。确定了针对MmmSC的不同抗体亚型的动力学。根据临床症状的严重程度、死后剖检和微生物学检查结果，将动物分为三组：有死亡的急性型、亚急性至慢性型和抗性动物。在整个实验期间，对照动物以及被分类为抗性的动物均未观察到血清转化。相反，对于所有其他患有急性或亚急性至慢性型疾病的牛，均检测到了血清转化。对于这些动物，在血清和BAL样本中检测到了IgM、IgG1、IgG2和IgA反应。两组动物中IgM、IgG1和IgG2反应的动力学几乎相似。因此，无法在这些亚型的水平与疾病严重程度之间建立明显的相关性。患有亚急性至慢性型疾病的动物的BAL和血清样本中IgA水平较高，并且在整个实验期间都趋于持续存在。相比之下，患有急性型疾病的动物的BAL样本中IgA水平较低，血清样本中IgA水平无或非常短暂且较低。因此，我们的结果表明，在实验性经接触感染MmmSC的牛中，IgA在局部产生，并且可能在预防传染性牛胸膜肺炎中发挥作用。
