The 44-kb Linear Plasmid Molecule in the Relapsing Fever Agent Borrelia duttonii Strain Ly Serve as a Preservation of vmp Genes

• Published in: Microbiology and immunology Vol. 46; no. 3; pp. 159 - 165
• Main Authors: Tabuchi, Norihiko, Mitani, Harumi, Seino, Satoshi, Fukunaga, Masahito
• Format: Journal Article
• Language: English
• Published: Tokyo Blackwell Publishing Ltd 01-01-2002; Center for Academic Publications Japan
• Subjects: Bacterial Outer Membrane Proteins - genetics; Bacteriology; Base Composition; Base Sequence; Biological and medical sciences; Borrelia - genetics; Borrelia duttonii; DNA, Bacterial; Fundamental and applied biological sciences. Psychology; Genes, Bacterial; Genetics; Lipoproteins - genetics; Microbiology; Molecular Sequence Data; Open Reading Frames; plasmid sequence; Plasmids; Relapsing Fever - microbiology; RT-PCR; Sequence Analysis, DNA; sequencing; vmp gene; Spirochaetaceae; Spirochaetales; Nucleotide sequence; Borrelia infection; Borrelia duttonii; Homology; Gene expression; Infection; Plasmid; Spirochaetosis; Antigenic variation; Bacteriosis; Bacteria; Relapsing fever
• ISSN: 0385-5600; 1348-0421
• DOI: 10.1111/j.1348-0421.2002.tb02681.x

Borrelia duttonii strain Ly, a causative agent of relapsing fever, contains a linear one megabase chromosome and 12 linear plasmid molecules. Here we report that the sequence of the 44‐kb linear plasmid of strain Ly is found to contain variable major protein (vmp) genes for antigenic variation of relapsing fever borreliae. The determined sequence is of 44,010 bp except for both ends of the molecule. Of 39 open reading frames (ORFs) found in the sequence, 21 ORFs (named vmpA to U) showed moderate similarities with vmp genes for Borrelia hermsii. However, most of the vmp homologues are apparently nonfunctional because of their frameshifts within the sequence and/or absence of promoter and ribosome‐binding signals upstream of their genes. RT‐PCR experiments using the specific primer for each vmp gene revealed that vmpE, one of the vmp genes, was expressed at the location of the 44‐kb plasmid molecule. The result suggests that the plasmid molecule may play a role in the preservation of the serotype switching of vmp genes in a mammalian host.