Genomic structure and rearrangement of the lysogenic bacteriophage pre-CTXΦ in four non-toxigenic strains of Vibrio cholerae serogroups O1 and O139
LI Xu, ZHAO Lin, FAN Fenxia, LI Zhe, LU Xin, PANG Bo, KAN Biao
State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, 102206, China
Abstract：The lysogenic phage CTXΦ of Vibrio cholerae can carry and transfer the cholera toxin gene ctxAB from toxigenic strains to non-toxigenic strains. CTXΦ also has a precursor, pre-CTXΦ，which does not carry ctxAB gene. In this study, we sequenced the genomes of four nontoxigenic serogroups O1 and O139 strains carrying pre-CTXΦ with the next generation sequencing. Both short-reading and long-reading sequencing were conducted to facilitate the assembly of long repeats. pre-CTXΦ prophage sequences were extracted from the genomes of these strains. The genes of CTXΦ receptor TcpA and the receptor-binding protein pIII in CTXΦ genome was subjected to sequence alignment, phylogenic tree construction and possible domains for protein-protein interactions. The tandem repeats of the different pre-CTXΦ alleles and their novel arrangement in the genomes were identified, and the precursor genome of classical type CTXΦ was also found. The arrangements of the pre-CTXΦ alleles in these strains were significantly different from the pandemic O1 El Tor strains. New sequences of the TcpA and the pIII were found in some strains. TcpA-pIII sequence correspondence analysis indicated the complicated interactions of the different sequence types of both proteins during the infection of pre-CTXΦ alleles. In addition, we have discovered a new type of pre-CTXΦ on small chromosome of VC702. The rstR-4 gene in VC702 has been disrupted by an insertion of a transposon which was firstly found in Klebsiella pneumoniae. Our study revealed new sequence types and arrangement of the pre-CTXΦ alleles and new evidence for better understanding the horizontal transfer of CTXΦ/pre-CTXΦ among the strains.
李旭，赵林，樊粉霞，李哲，卢昕，逄波，阚飙. 4株霍乱弧菌非产毒株溶源性噬菌体pre-CTXΦ的基因组结构分析[J]. 微生物与感染, 2019, 14(4): 216-224.
LI Xu, ZHAO Lin, FAN Fenxia, LI Zhe, LU Xin, PANG Bo, KAN Biao. Genomic structure and rearrangement of the lysogenic bacteriophage pre-CTXΦ in four non-toxigenic strains of Vibrio cholerae serogroups O1 and O139. JOURNAL OF MICROBES AND INFECTIONS, 2019, 14(4): 216-224.
2019, Vol. 14 
