霍乱弧菌通常是水生的非致病菌。但在某些情况下可获得毒力,引起烈性传染病——霍乱。尽管这一转变细节仍不清楚,但已发现了其中关键性的一步:即致病菌可以某种方式从其它菌株获得致病性。研究发现,编码霍乱毒素的基因存在于一种霍乱噬菌体中,且该噬菌体还包含一些有利于它在细菌间传播的基因。 霍乱肠毒素基因位于一个称CTX的片段上。该片段至少还包括了其它6个基因。为了研究CTX片段的传递性,研究者们用一 Vibrio cholerae are usually aquatic non-pathogenic bacteria. However, in some cases virulence is acquired, causing a severe infectious disease - cholera. Although details of this shift remain unclear, one of the key steps has been found: pathogenic bacteria can somehow acquire pathogenicity from other strains. The study found that the gene encoding cholera toxin is present in a cholera phage and that the phage contains some genes that facilitate its spread between bacteria. The cholera enterotoxin gene is located on a fragment called CTX. The fragment contains at least the other six genes. In order to study the transmissibility of CTX fragments, the researchers used one