Submitted to: Federation of European Microbiological Societies Microbiology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2003
Publication Date: 7/25/2003
Citation: STANTON, T.B., THOMPSON, M.G., HUMPHREY, S.B., ZUERNER, R.L. DETECTION OF BACTERIOPHAGE VSH-1 SVP38 GENE IN BRACHYSPIRA SPIROCHETES. FEDERATION OF EUROPEAN MICROBIOLOGICAL SOCIETIES MICROBIOLOGY LETTERS. 2003. V. 224. P. 225-229. Interpretive Summary: Brachyspira hyodysenteriae is a helical-shaped bacterium that causes the disease swine dysentery. There is a growing and realistic concern that limitations in feed antibiotic use will result in increases in the incidence of certain animal diseases, such as swine dysentery. Alternative disease control strategies (for example, vaccines) will benefit from, if not require, tools and techniques for genetically attenuating virulent strains of B. hyodysenteriae. In these studies, one genetic tool, VSH-1, a bacteriophage virus that transfers genes between B. hyodysenteriae cells, was characterized at the gene level. One of the genes for this virus was detected in bacterial groups that are related to B. hyodysenteriae. These groups include another swine pathogen, B. pilosicoli, and B. alvinipulli, the bacterium that causes chicken diarrhea. These results are important because they imply genetic tools like VSH-1 are available for use to genetically modify the pathogens B. pilosicoli and B. alvinipulli. They also indicate a possible mechanism for spreading genes, importantly antibiotic resistance genes, among these bacteria.
Technical Abstract: VSH-1 is a mitomycin C-inducible, nonlytic, phage-like agent that packages random 7.5 kb fragments of the Brachyspira hyodysenteriae genome. VSH-1 is the first recognized mechanism for gene transfer between B. hyodysenteriae cells. A 343-bp region of gene svp38, encoding the VSH-1 major head protein, was amplified from B. hyodysenteriae genomic DNA by PCR. The amplicon was used as a probe in Southern blot hybridizations to detect homologous svp38 genes in the digested genomic DNA's of 27 Brachyspira strains. The VSH-1 svp- 38 gene was associated with a 40 kb SalI-SmaI fragment of the B. hyodysenteriae B78**T chromosome, indicating VSH-1 DNA insertion into the chromosome at a unique site. Restriction endonuclease digested DNA's of twenty-seven spirochete strains representing six Brachyspira species (B. hyodysenteriae, B. innocens, B. pilosicoli, B. murdochii, B. intermedia, B. alvinipulli), contained a single fragment which hybridized with the svp38 gene probe. Digested DNA's of other spirochete genera (Treponema, Spirochaeta, Borrelia, Leptospira) did not hybridize with the probe. VSH-1-like agents appear to be widely distributed among Brachyspira species and, as demonstrated for B. hyodysenteriae, may serve as useful gene transfer agents.