Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar, Braga, Portugal.
J Appl Microbiol. 2010 Apr;108(4):1175-86. doi: 10.1111/j.1365-2672.2009.04549.x. Epub 2009 Sep 30.
Salmonella is a worldwide foodborne pathogen causing acute enteric infections in humans. In the recent years, the use of bacteriophages has been suggested as a possible tool to combat this zoonotic pathogen in poultry farms. This work aims to isolate and perform comparative studies of a group of phages active against a collection of specific Salmonella Enteritidis strains from Portugal and England. Also, suitable phage candidates for therapy of poultry will be selected.
The Salm. Enteritidis strains studied were shown to have a significantly high occurrence of defective (cryptic) prophages; however, no live phages were found in the strains. Bacteriophages isolated from different environments lysed all except one of the tested Salm. Enteritidis strains. The bacteriophages studied were divided into different groups according to their genetic homology, RFLP profiles and phenotypic features, and most of them showed no DNA homology with the bacterial hosts. The bacteriophage lytic efficacy proved to be highly dependent on the propagation host strain.
Despite the evidences shown in this work that the Salm. Enteritidis strains used did not produce viable phages, we have confirmed that some phages, when grown on particular hosts, behaved as complexes of phages. This is most likely because of the presence of inactive phage-related genomes (or their parts) in the bacterial strains which are capable of being reactivated or which can recombine with lytic phages. Furthermore, changes of the bacterial hosts used for maintenance of phages must be avoided as these can drastically modify the parameters of the phage preparations, including host range and lytic activity.
This work shows that the optimal host and growth conditions must be carefully studied and selected for the production of each bacteriophage candidate for animal therapy.
沙门氏菌是一种全球性的食源性病原体，可导致人类急性肠道感染。近年来，噬菌体的应用被认为是对抗家禽养殖场中这种人畜共患病原体的一种可能工具。本研究旨在分离和比较一组针对来自葡萄牙和英国的特定肠炎沙门氏菌分离株的噬菌体，并选择适合治疗家禽的噬菌体候选物。
研究表明，所研究的肠炎沙门氏菌菌株中存在大量缺失（隐秘）原噬菌体，但在这些菌株中未发现活噬菌体。从不同环境中分离的噬菌体可裂解除一株外的所有测试肠炎沙门氏菌菌株。根据遗传同源性、RFLP 图谱和表型特征，对分离到的噬菌体进行分组，其中大多数噬菌体与细菌宿主无 DNA 同源性。噬菌体的溶菌效果高度依赖于繁殖宿主菌株。
尽管本研究表明所使用的肠炎沙门氏菌菌株不产生有活力的噬菌体，但我们已经证实，当在特定宿主上生长时，一些噬菌体表现为噬菌体复合物。这很可能是因为细菌菌株中存在无活性的噬菌体相关基因组（或其部分），这些基因组能够被重新激活或与溶菌噬菌体发生重组。此外，必须避免改变用于维持噬菌体的细菌宿主，因为这会极大地改变噬菌体制剂的参数，包括宿主范围和溶菌活性。
本研究表明，必须仔细研究和选择每种动物治疗用噬菌体候选物的最佳宿主和生长条件。
