Submitted to: Gordon Research Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 1/5/2004
Publication Date: 1/25/2004
Citation: MATSON, E.G., HUMPHREY, S.B., ZUERNER, R.L., STANTON, T.B. CHARACTERISTICS OF VSH-1 GENE TRANSCRIPTION IN BRACHYSPIRA HYODYSENTERIAE. PROCEEDINGS OF THE GORDON RESEARCH CONFERENCE. 2004. P. 2. Interpretive Summary:
Technical Abstract: Brachyspira hyodysenteriae (B. hyo.) is an anaerobic spirochete and the infectious agent of dysentery in swine. B. hyo. cells harbor the mitomycin C-inducible, non self-replicating prophage VSH-1. VSH-1 virions randomly package 7.5 Kb fragments of B. hyo. chromosomal DNA and mediate horizontal gene transfer in B. hyo. cell populations. The VSH-1 genes that are currently known, constitute a 15.7 Kb region of the B. hyo. chromosome. Little is known about the intracellular and extracellular processes that control the production of VSH-1. Consequently, as a first step toward understanding VSH-1 regulatory mechanisms, we have been investigating the organization of the VSH-1 operon and transcription of VSH-1 associated genes during the switch from lysogeny to lysis. RNA slot blot hybridization determined that transcription levels of VSH-1 genes increased 6- to 28-fold, reaching a maximum level between 3 and 4 hours over a 6-hour time period following mitomycin C treatment of B. hyo. cell cultures. By contrast, mRNA levels of a constitutively expressed B. hyo. flagellar sheath gene (flaA1) declined over the same period. These results are consistent with a general shift from cellular to viral transcription following VSH-1 induction. Reverse transcriptase PCR amplification of VSH-1 intergenic regions indicate that VSH-1 genes share either a common transcript or overlapping transcpripts beginning with svp45 (a VSH-1 capsid structural gene) and continuing through a putative lysin gene. Primer extension analysis identified transcriptional start sites located 29 bp upstream and 13 bp and 34 bp downstream from the svp45 ORF start codon. These results provide a foundation for future investigations into identifying regulatory genes and environmental factors involved in triggering VSH-1 production.