重组T4噬菌体gp37基因可扩大其在沙门氏菌中的宿主范围

Recombinant T4 coliphage gp37 gene can expand its host range in Salmonella

摘要:

[目的]将T4噬菌体WG01宿主决定区的gp37基因片段，与另一株T4噬菌体QL01的相应基因进行同源重组，从而获得嵌合噬菌体并进行宿主谱分析，为阐明T4噬菌体的宿主谱形成机制以及快速筛选针对特定病原菌的噬菌体奠定了基础。[方法]通过同源重组的方法将WG01gp37上的8个基因片段分别替换给QL01，用沙门氏菌作为宿主菌筛选嵌合噬菌体，并对嵌合噬菌体进行宿主谱、最佳感染复数、一步生长曲线和遗传稳定性测定。[结果]本研究共获得了5株嵌合噬菌体（QWA、QWC、QWF、QWG、QWFG）。宿主谱试验结果表明，与噬菌体QL01相比，嵌合噬菌体对21株沙门宿主菌分别可以多裂解7、8、4、10和9株菌，即嵌合噬菌体都获得了相对较宽的宿主谱，其中QWG的沙门氏菌宿主菌拓宽最多。生物学特性试验结果表明，嵌合噬菌体QWG生物学特性稳定。嵌合噬菌体QWG经连续传代培养20代，测序分析第1代和第20代嵌合噬菌体尾丝蛋白基因在传代过程中的稳定性，测序结果表明，嵌合噬菌体改造部分的基因能稳定遗传。[结论]用基因改造的方法可以产生宿主谱拓宽且能稳定遗传的嵌合噬菌体，为快速筛选针对特定病原菌的噬菌体提供了可能。

关键词:基因改造;嵌合噬菌体;宿主谱;同源重组;生物学特性

Abstract:

[Objective] In this study, the host range of phage QL01 was changed by replacing the gene fragment of QL01 gp37. This lays the foundation for studying the host range mechanism of T4 phage and rapid screening of phages targeting specific pathogens. [Methods] Eight gene fragments on WG01 gp37 were substituted by QL01 using homologous recombination, and then the different chimeric phages were screened and their host range determined by using Salmonella as the host strain. Finally, the biological characteristics such as the optimal multiplicity of infection, one-step growth curve, and other biological characteristics of the chimeric phage QWG were analyzed, as well as the genetic stability. [Results] A total of five chimeric phages (QWA, QWC, QWF, QWG, QWFG) were obtained in this experiment. The results of the host range analysis test showed that chimeric phage could lyse 7, 8, 4, 10 and 9 strains of Salmonella, respectively, compared to phage QL01. That is to say, chimeric phages have all obtained a relatively broad host range of which the host bacteria of QWG widened the most. The results of biological characteristics test showed that the chimeric phage QWG has stable biological properties. We cultured the chimeric phage QWG continuously for 20 generations, sequenced the tail genes from the first and 20th generation chimeric phage and analyzed their hereditary stability. The sequencing results indicated that the gene fragment of the chimeric phage engineered part could stably inherit. [Conclusion] Genetic engineering can generate chimeric phage with broadened host range and hereditary stability, which provides a possibility for rapid screening of phage against specific pathogens.

Key words:genetic engineered;chimeric phage;host range;homologous recombination;biological characteristics