Myers L E, Yang Y P, Du R P, Wang Q, Harkness R E, Schryvers A B, Klein M H, Loosmore S M
Pasteur Merieux Connaught Canada Research, North York, Ontario, Canada M2R 3T4.
Infect Immun. 1998 Sep;66(9):4183-92. doi: 10.1128/IAI.66.9.4183-4192.1998.
The transferrin binding protein genes (tbpA and tbpB) from two strains of Moraxella catarrhalis have been cloned and sequenced. The genomic organization of the M. catarrhalis transferrin binding protein genes is unique among known bacteria in that tbpA precedes tbpB and there is a third gene located between them. The deduced sequences of the M. catarrhalis TbpA proteins from two strains were 98% identical, while those of the TbpB proteins from the same strains were 63% identical and 70% similar. The third gene, tentatively called orf3, encodes a protein of approximately 58 kDa that is 98% identical between the two strains. The tbpB genes from four additional strains of M. catarrhalis were cloned and sequenced, and two potential families of TbpB proteins were identified based on sequence similarities. Recombinant TbpA (rTbpA), rTbpB, and rORF3 proteins were expressed in Escherichia coli and purified. rTbpB was shown to retain its ability to bind human transferrin after transfer to a membrane, but neither rTbpA nor rORF3 did. Monospecific anti-rTbpA and anti-rTbpB antibodies were generated and used for immunoblot analysis, which demonstrated that epitopes of M. catarrhalis TbpA and TbpB were antigenically conserved and that there was constitutive expression of the tbp genes. In the absence of an appropriate animal model, anti-rTbpA and anti-rTbpB antibodies were tested for their bactericidal activities. The anti-rTbpA antiserum was not bactericidal, but anti-rTbpB antisera were found to kill heterologous strains within the same family. Thus, if bactericidal ability is clinically relevant, a vaccine comprising multiple rTbpB antigens may protect against M. catarrhalis disease.
已克隆并测序了来自两株卡他莫拉菌的转铁蛋白结合蛋白基因（tbpA和tbpB）。卡他莫拉菌转铁蛋白结合蛋白基因的基因组组织在已知细菌中是独特的，因为tbpA位于tbpB之前，且它们之间有第三个基因。两株卡他莫拉菌的TbpA蛋白推导序列的同一性为98%，而同一菌株的TbpB蛋白推导序列的同一性为63%，相似性为70%。第三个基因暂称为orf3，编码一种约58 kDa的蛋白，两株菌之间该蛋白的同一性为98%。克隆并测序了另外四株卡他莫拉菌的tbpB基因，并根据序列相似性鉴定出两个潜在的TbpB蛋白家族。重组TbpA（rTbpA）、rTbpB和rORF3蛋白在大肠杆菌中表达并纯化。rTbpB转移至膜上后仍保留与人转铁蛋白结合的能力，但rTbpA和rORF3均无此能力。制备了单特异性抗rTbpA和抗rTbpB抗体并用于免疫印迹分析，结果表明卡他莫拉菌TbpA和TbpB的表位在抗原性上是保守的，且tbp基因呈组成型表达。在缺乏合适动物模型的情况下，检测了抗rTbpA和抗rTbpB抗体的杀菌活性。抗rTbpA抗血清无杀菌作用，但发现抗rTbpB抗血清可杀死同一家族的异源菌株。因此，如果杀菌能力具有临床相关性，一种包含多种rTbpB抗原的疫苗可能预防卡他莫拉菌病。
