Jouravleva Elena A, McDonald Gregory A, Garon Claude F, Boesman-Finkelstein Mary, Finkelstein Richard A
Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212, USA.
Rocky Mountain Laboratories, Hamilton, MT 59840, USA.
Microbiology (Reading). 1998 Feb;144 ( Pt 2):315-324. doi: 10.1099/00221287-144-2-315.
The emergence and rapid rise to dominance of Vibrio cholerae O139 in India and Bangladesh in 1992 led to the consideration that choleraphage might serve as both a selective mechanism and a means for horizontal transmission of genetic information. A filamentous phage '493' from O139 strain AJ27-493 has been purified and partially characterized. The phage was inactive on classical biotype V. cholerae O1 but it was active on El Tor biotype strains isolated prior to 1994 when El Tor re-emerged in Bangladesh. More recent El Tor isolates were all resistant to the phage. The phage was also active on O139 strains. Unlike the filamentous ctx phi, the receptor for 493 is not TcpA. The phage genome was a 9.3 kb closed circular single-stranded molecule containing a 0.4 kb double-stranded stem supporting a 2 kb single-stranded loop. A 283 bp fragment was cloned and used as a probe in Southern hybridization, in parallel with total phage 493 DNA. These probes hybridized both chromosomally and extrachromosomally with most O139 strains, but not with O1 strains. Infection of hybridization-negative El Tor or O139 strains resulted in the presence of hybridizing loci (both plasmid and chromosomal), in the appearance of an 18 kDa protein, and in marked alterations in colonial morphology. Phage 493 is clearly distinct from other O139 choleraphages which have been described. Phage 493 DNA hybridized with an encapsulated non-O1 (O31) strain (NRT36S) which was isolated before O139 was recognized. NRT36S also produces a phage which can infect El Tor strains with low efficiency. Further studies may reveal whether bacteriophage play a role in the emergence and the territoriality of new choleragenic vibrios.
1992年霍乱弧菌O139在印度和孟加拉国出现并迅速占据主导地位，这使得人们认为霍乱噬菌体可能既是一种选择机制，也是遗传信息水平传播的一种方式。一种来自O139菌株AJ27 - 493的丝状噬菌体“493”已被纯化并进行了部分特性鉴定。该噬菌体对经典生物型霍乱弧菌O1无活性，但对1994年埃尔托生物型在孟加拉国再次出现之前分离的埃尔托生物型菌株有活性。最近分离的埃尔托菌株均对该噬菌体有抗性。该噬菌体对O139菌株也有活性。与丝状ctx噬菌体不同，493的受体不是TcpA。噬菌体基因组是一个9.3 kb的闭环单链分子，包含一个0.4 kb的双链茎，支撑着一个2 kb的单链环。一个283 bp的片段被克隆，并与总噬菌体493 DNA平行用作Southern杂交的探针。这些探针与大多数O139菌株的染色体和染色体外均发生杂交，但与O1菌株不杂交。对杂交阴性的埃尔托或O139菌株进行感染后，会出现杂交位点（质粒和染色体）、出现一种18 kDa的蛋白质，并使菌落形态发生明显改变。噬菌体493显然与已描述的其他O139霍乱噬菌体不同。噬菌体493 DNA与一种在O139被识别之前分离的包膜非O1（O31）菌株（NRT36S）发生杂交。NRT36S也产生一种噬菌体，该噬菌体能够以低效率感染埃尔托菌株。进一步的研究可能会揭示噬菌体在新的产霍乱毒素弧菌的出现和地域性方面是否发挥作用。
