Kuhnert P, Berthoud H, Straub R, Frey J
Institute of Veterinary Bacteriology, University of Bern, Langgassstrasse 122, CH-3012 Bern, Switzerland.
Vet Microbiol. 2003 Mar 20;92(1-2):161-7. doi: 10.1016/s0378-1135(02)00353-x.
We assessed and compared host cell specificity of the haemolytic and cytotoxic activity of the RTX toxins from Actinobacillus equuli, an equine pathogen, and Actinobacillus suis, which is pathogenic for pigs. The two bacterial species are closely related, phenotypically as well as phylogenetically, sharing the same 16S rRNA gene sequence. Both species contain specific protein toxins from the family of pore-forming RTX toxins, however, the two species differ in their RTX toxin profiles. Haemolytic A. equuli contains the operon for the Aqx toxin, whereas A. suis harbours genes for ApxI and ApxII. We tested the toxic activity of the corresponding proteins on erythrocytes as well as on lymphocytes isolated from horse and pig blood. The strength of the haemolytic activity for each of the toxins was independent of the origin of erythrocytes. When testing cytotoxic activity, the Aqx protein showed a higher toxic effect for horse lymphocytes than for porcine lymphocytes. On the other hand, ApxI and ApxII showed a strong cytotoxic effect on porcine lymphocytes and a reduced toxicity for horse lymphocytes; the toxicity of ApxII was generally much lower than ApxI. Our results indicate a host species specificity of the toxic activity of RTX toxins Aqx of A. equuli and ApxI and ApxII of A. suis.
我们评估并比较了马源致病菌马驹放线杆菌（Actinobacillus equuli）和猪源致病菌猪放线杆菌（Actinobacillus suis）的RTX毒素溶血活性和细胞毒性的宿主细胞特异性。这两种细菌在表型和系统发育上密切相关，共享相同的16S rRNA基因序列。两种细菌均含有成孔RTX毒素家族的特定蛋白毒素，然而，这两种细菌的RTX毒素谱有所不同。溶血活性的马驹放线杆菌含有Aqx毒素操纵子，而猪放线杆菌含有ApxI和ApxII基因。我们测试了相应蛋白对从马血和猪血中分离出的红细胞以及淋巴细胞的毒性活性。每种毒素的溶血活性强度与红细胞来源无关。在测试细胞毒性活性时，Aqx蛋白对马淋巴细胞的毒性作用高于对猪淋巴细胞的毒性作用。另一方面，ApxI和ApxII对猪淋巴细胞显示出强烈的细胞毒性作用，而对马淋巴细胞的毒性降低；ApxII的毒性通常远低于ApxI。我们的结果表明，马驹放线杆菌的RTX毒素Aqx以及猪放线杆菌的ApxI和ApxII的毒性活性具有宿主物种特异性。
