Radwanska Magdalena, Chamekh Mustapha, Vanhamme Luc, Claes Filip, Magez Stefan, Magnus Eddy, de Baetselier Patrick, Büscher Philippe, Pays Etienne
Department of Parasitology, Institute of Tropical Medicine, Antwerp, Belgium.
Am J Trop Med Hyg. 2002 Dec;67(6):684-90. doi: 10.4269/ajtmh.2002.67.684.
In the search for new diagnostic methods that would distinguish Trypanosoma brucei rhodesiense from T. b. brucei and T. b. gambiense, we have developed two polymerase chain reaction (PCR) primer sets. The first primer set was derived from the serum resistance-associated (SRA) gene of T. b. rhodesiense that confers resistance to lysis by normal human serum (NHS). The specificity of the SRA-based PCR was tested on 97 different trypanosome populations originating from various taxonomic groups, host species, and geographic regions. Only one of 25 T. b. rhodesiense samples was negative in this PCR, and none of 72 other samples were positive in this assay. Interestingly, a reference T. brucei strain (TREU927/4) currently used for genome sequencing was negative for the SRA gene; however, this strain was resistant to lysis by NHS. The second primer set was derived from a specific variant surface glycoprotein (VSG) expression site where the SRA gene is expressed (R-ES). This primer set identified the strain as T. b. rhodesiense in 17 of 17 SRA gene-positive strains in which it was tested. These data strongly suggest that expression of the SRA gene is generally involved in resistance to lysis by NHS in T. b. rhodesiense strains.
在寻找能够区分罗德西亚布氏锥虫与布氏布氏锥虫及布氏冈比亚锥虫的新诊断方法的过程中，我们研发了两套聚合酶链反应（PCR）引物组。第一套引物组源自罗德西亚布氏锥虫的血清抗性相关（SRA）基因，该基因赋予了对正常人血清（NHS）裂解的抗性。基于SRA的PCR的特异性在来自不同分类群、宿主物种和地理区域的97个不同锥虫群体上进行了测试。在这25个罗德西亚布氏锥虫样本中只有1个在该PCR中呈阴性，而其他72个样本在该检测中均无阳性结果。有趣的是，目前用于基因组测序的布氏锥虫参考菌株（TREU927/4）的SRA基因呈阴性；然而，该菌株对NHS的裂解具有抗性。第二套引物组源自SRA基因表达的特定可变表面糖蛋白（VSG）表达位点（R-ES）。在对其进行测试的17个SRA基因阳性菌株中，该引物组在其中17个菌株中鉴定出该菌株为罗德西亚布氏锥虫。这些数据有力地表明，SRA基因的表达通常与罗德西亚布氏锥虫菌株对NHS裂解的抗性有关。
