Jolie R A, Mulks M H, Thacker B J
Department of Large Animal Clinical Sciences, Michigan State University, East Lansing 48824.
Vet Microbiol. 1994 Feb;38(4):329-49. doi: 10.1016/0378-1135(94)90151-1.
Two distinct antigenic subtypes of Actinobacillus pleuropneumoniae serotype 1 were identified via coagglutination (Co-A) and designated as 1A and 1B. The reference strains, ATCC 27088 (1A) and ISU 158 (1B), were used to prepare hyperimmune rabbit sera for Co-A reagents. Of 75 serotype 1 field isolates tested by Co-A, 35 isolates typed as 1A, 12 as 1B and 28 as 1A/1B. Significant cross-reactivity between the 2 subtypes was found in the Co-A and was eliminated in 20/28 1A/1B strains by using Co-A reagents prepared with rabbit sera absorbed with the heterologous reference strain. However, twelve isolates (5 1A and 7 1A/1B; 16%) showed no reaction with Co-A reagents prepared with absorbed sera. Immunoblots of outer membranes (OM) prepared from APP 1A or 1B reference strains and field isolates indicated that antigenic differences between subtypes 1A and 1B were located within the high molecular weight (MW) region of the gels (40-100 kDa). Hyperimmune rabbit sera against 1A or 1B and sera from pigs vaccinated with whole-cell, formalin inactivated 1A or 1B bacterins reacted with the high MW region only in strains of the homologous subtype. In contrast, 4 of 5 sera from 1B infected pigs and 2 of 5 sera from 1A infected pigs reacted with all APP serotype 1 strains regardless of subtype. Apparently, infection exposed cross-reactive antigenic determinants that were not exposed by immunization with killed bacteria preparations. SDS-PAGE gels with LPS purified from APP 1A, 1B, 9 and 11 showed that 1A, 9 and 11 LPS O-antigens had an identical smooth ladder pattern, while 1B LPS was distinctly different. In immunoblots with OM or LPS and in dot-immunobinding assays with LPS, rabbit antiserum against APP 1A reacted with 1A, 9 and 11. In contrast, rabbit antiserum against APP 1B only reacted with APP 1B and weakly with APP 9 in the OM immunoblot and with LPS from APP 1B, 9 and 11 in the LPS immunoblot and dot-immunobinding assay. We conclude that 2 subtypes of APP serotype 1 can be distinguished based on their antigenic differences. These differences are located, at least in part, within the LPS O-antigens. LPS O-antigens from APP 1B appear more antigenically similar to APP 9 LPS than to either APP 1A or APP 11 LPS. There may also be antigenic differences in the capsular polysaccharides of APP 1A and 1B strains.(ABSTRACT TRUNCATED AT 400 WORDS)
通过协同凝集试验（Co-A）鉴定出胸膜肺炎放线杆菌血清型1的两种不同抗原亚型，分别命名为1A和1B。使用参考菌株ATCC 27088（1A）和ISU 158（1B）制备用于Co-A试剂的超免疫兔血清。在通过Co-A检测的75株血清型1的田间分离株中，35株为1A型，12株为1B型，28株为1A/1B型。在Co-A试验中发现这两种亚型之间存在显著交叉反应，通过使用用异源参考菌株吸收的兔血清制备的Co-A试剂，28株1A/1B菌株中的20株交叉反应被消除。然而，12株分离株（5株1A型和7株1A/1B型；16%）与用吸收血清制备的Co-A试剂无反应。对APP 1A或1B参考菌株及田间分离株制备的外膜（OM）进行免疫印迹分析表明，1A和1B亚型之间的抗原差异位于凝胶的高分子量（MW）区域（40-100 kDa）。针对1A或1B的超免疫兔血清以及用全细胞、甲醛灭活的1A或1B菌苗免疫的猪血清仅与同源亚型菌株的高分子量区域发生反应。相比之下，5份来自1B感染猪的血清中有4份以及5份来自1A感染猪的血清中有2份与所有APP血清型1菌株发生反应，而不论其亚型如何。显然感染暴露了交叉反应性抗原决定簇，而用灭活细菌制剂免疫则未暴露这些决定簇。从APP 1A、1B、9和11中纯化的脂多糖（LPS）进行的SDS-PAGE凝胶分析表明，1A、9和11的LPS O抗原具有相同的平滑梯状图谱，而1B的LPS则明显不同。在用OM或LPS进行的免疫印迹分析以及用LPS进行的斑点免疫结合试验中，针对APP 1A的兔抗血清与1A、9和11发生反应。相比之下，针对APP 1B的兔抗血清仅与APP 1B发生反应，在OM免疫印迹中与APP 9微弱反应，在LPS免疫印迹和斑点免疫结合试验中与APP 1B、9和11的LPS发生反应。我们得出结论，APP血清型1的两种亚型可根据其抗原差异进行区分。这些差异至少部分位于LPS O抗原中。APP 1B的LPS O抗原在抗原性上似乎与APP 9的LPS更相似，而不是与APP 1A或APP 11的LPS相似。APP 1A和1B菌株的荚膜多糖之间也可能存在抗原差异。（摘要截短至400字）
