Eamens G J, Gonsalves J R, Whittington A-M, Turner B
NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Camden New South Wales, 2570, Australia.
Aust Vet J. 2012 Jun;90(6):225-34. doi: 10.1111/j.1751-0813.2012.00934.x.
To compare the sensitivity and specificity of six serological enzyme-linked immunosorbent assays (ELISAs) based on serovar-independent antigens of Actinobacillus pleuropneumoniae (App) and investigate cross-reactivity in disease-free pigs challenged with Mycoplasma hyopneumoniae and Pasteurella multocida.
Five experimental pig trials using direct challenge with App serovars 1, 7 or 15 or direct challenge with M. hyopneumoniae and/or various dose rates of P. multocida.
A 39-kDa outer membrane protein antigen and five recombinant antigens from the apxIVA gene of App were evaluated. The latter were derived from the ApxIVA N-terminus (ApxIVA-N, ApxIVA-NP, ApxIVA-NPS) or C-terminus (ApxIVA-C, ApxIVA-CP). Pigs were sampled after challenge and clinical and necropsy findings evaluated.
The 39-kDa ELISA had high sensitivity but lacked specificity, with significantly increased cross-reactivity following P. multocida challenge. ELISAs based on ApxIVA N-terminus antigens were significantly more sensitive than C-terminus antigens for the detection of App-induced disease. Although ApxIVA-N and ApxIVA-NP ELISAs had increased reactivity following P. multocida challenge, they retained high specificity for App-induced disease (90-93%). Affinity purified ApxIVA-NP antigen had marginally better specificity than ApxIVA-N, without reduced sensitivity. Mycoplasma hyopneumoniae did not affect serological cross-reactivity. In disease-free pigs, the specificity of the ApxIVA-NPS ELISA may be adversely affected by nasal carriage of apparently low-virulence App strains.
ApxIVA-N-based ELISAs can be used for evaluating App status in commercial herds, but some appear limited by high carriage rates of low-virulence App. The 39-kDa antigen is only of merit in exclusion of App disease by negative serology.
比较基于胸膜肺炎放线杆菌（App）血清型非依赖性抗原的六种血清学酶联免疫吸附测定（ELISA）的敏感性和特异性，并研究在受到猪肺炎支原体和多杀性巴氏杆菌攻击的无病猪中的交叉反应性。
五项实验性猪试验，分别用App血清型1、7或15直接攻击，或用猪肺炎支原体和/或不同剂量率的多杀性巴氏杆菌直接攻击。
评估一种39 kDa外膜蛋白抗原和来自App的apxIVA基因的五种重组抗原。后者来自ApxIVA N端（ApxIVA-N、ApxIVA-NP、ApxIVA-NPS）或C端（ApxIVA-C、ApxIVA-CP）。攻击后对猪进行采样，并评估临床和尸检结果。
39 kDa ELISA具有高敏感性但缺乏特异性，在多杀性巴氏杆菌攻击后交叉反应性显著增加。基于ApxIVA N端抗原的ELISA在检测App引起的疾病方面比C端抗原显著更敏感。尽管ApxIVA-N和ApxIVA-NP ELISA在多杀性巴氏杆菌攻击后反应性增加，但它们对App引起的疾病仍保持高特异性（90-93%）。亲和纯化的ApxIVA-NP抗原的特异性略优于ApxIVA-N，且敏感性未降低。猪肺炎支原体不影响血清学交叉反应性。在无病猪中，ApxIVA-NPS ELISA的特异性可能会受到明显低毒力App菌株鼻腔携带的不利影响。
基于ApxIVA-N的ELISA可用于评估商业猪群中的App状况，但有些似乎受到低毒力App高携带率的限制。39 kDa抗原仅在通过阴性血清学排除App疾病方面有价值。
