El Tor型CTXΦ对O1群不同霍乱弧菌的转染性研究

Study on infection of different strains of Vibro cholerae O1 by El Tor CTXΦ

研究丝状噬菌体CTXΦ对O1群不同霍乱弧菌的水平转移效率及菌株的噬菌体免疫能力.利用带有氯霉素抗性基因遗传标记的CTXETΦ感染颗粒对O1群的4株不同霍乱弧菌进行体外和体内转染实验,根据氯霉素抗性筛选转染子,通过Southern Blot等方法进行验证并判断CTXΦ基因组的存在形式,计算比较不同菌株的转染率,分析转染及噬菌体免疫机制.带有遗传标记的CTXETΦ对古典型霍乱弧菌1119的体内转染率高于体外;体内转染实验中,古典菌株1119的转染率远高于其它3株El Tor型霍乱弧菌;在El Tor型霍乱弧菌中,不含rstR基因的IEM101的转染率高于另外两株带有rstR基因的霍乱弧菌2～3个数量级.古典型霍乱弧菌比El Tor型菌株对CTXETΦ噬菌体颗粒更易感,TCP菌毛的表达和rstR基因介导的噬菌体免疫影响CTXΦ在霍乱弧菌中的水平转移.

To study the horizontal transfer efficiencies of filamentous bacteriophage CTXΦ in different V. cholera O1 strains and the phage immunities of these strains. The infectious E1 Tor CTXΦ particles genetic marked by chloramphenicol resistance gene were used to infect four different V. cholerae O1 strains in vivo and in vitro. Selected the infected clones based on its character of chloramphenicol resistance and identified and judged the exist form of CTXΦ genome through Southern bolt and other hybridization methods. Calculated the infection rates of different strains and compared each other. Then we analyzed the mechanism of infection and phage immunity. The infection rate of classic strain 1119 with the genetic marked CTX^ETΦ in vivo is much higher than that in vitro. In vitro experiment, the rate of 1119 is higher than other three E1 Tor strains. And in E1 Tor strains, the infection frequency of IEM101 that had no rstR gene is 100 to 1000 times higher than other two strains containing rstR. Classical biotype strain is more susceptible to CTX^ETΦ particles than E1 Tor strains. Expression of TCP and the phage immunity mediated by rstR gene affect the horizontal transfection of CTXΦ in V. cholerae strains.