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The expression of flagellin genes in most bacteria is typically regulated by the flagellum-specific [sigma.sup.28] factor FliA, and an [anti-sigma.sup.28] factor, FlgM. However, the regulatory hierarchy in several bacteria that have multiple flagellins is more complex. In these bacteria, the flagellin genes are often transcribed by at least two different sigma factors. The flagellar filament in spirochetes consists of one to three FlaB core proteins and at least one FlaA sheath protein. Here, the genetically amenable bacterium Brachyspira hyodysenteriae was used as a model spirochete to investigate the regulation of its four flagellin genes, flaA, flaB1, flaB2, and flaB3. We found that the flaB1 and flaB2 genes are regulated by [sigma.sup.28], whereas the flaA and flaB3 genes are controlled by [sigma.sup.70]. The analysis of a flagellar motor switch fliG mutant further supported this proposition; in the mutant, the transcription of flaB1 and flaB2 was inhibited, but that of flaA and flaB3 was not. In addition, the continued expression of flaA and flaB3 in the mutant resulted in the formation of incomplete flagellar filaments that were hollow tubes and consisted primarily of FlaA. Finally, our recent studies have shown that each flagellin unit contributes to the stiffness of the periplasmic flagella, and this stiffness directly correlates with motility. The regulatory mechanism identified here should allow spirochetes to change the relative ratio of these flagellin proteins and, concomitantly, vary the stiffness of their flagellar filament. doi: 10.1128/JB.01502-09

The filaments of spirochete periplasmic flagella (PFs) have a unique structure and protein composition. In most spirochetes, the PFs consist of a core of at least three related proteins (FlaB1, FlaB2, and FlaB3) and a sheath of FlaA protein. The functions of these filament proteins remain unknown. In this study, we used a multidisciplinary approach to examine the role of these proteins in determining the composition, shape, and stiffness of the PFs and how these proteins impact motility by using the spirochete Brachyspira (formerly Treponema, Serpulina) hyodysenteriae as a genetic model. A series of double mutants lacking combinations of these PF proteins was constructed and analyzed. The results show the following. First, the diameters of PFs are primarily determined by the sheath protein FlaA, and that FlaA can form a sheath in the absence of an intact PF core. Although the sheath is important to the PF structure and motility, it is not essential. Second, the three core proteins play unequal roles in determining PF structure and swimming speed. The functions of the core proteins FlaB1 and FlaB2 overlap such that either one of these proteins is essential for the spirochete to maintain the intact PF structure and for cell motility. Finally, linear elasticity theory indicates that flagellar stiffness directly affects the spirochete's swimming speed.

The bacterial diversity in fecal samples of a wild gorilla is described by using a 16S rRNA gene clone library and terminal-restriction fragment length polymorphism (T-RFLP). The results have indicated that fecal populations did not change temporarily, as examined by T-RFLP.

Lipoproteins are of great interest in understanding the molecular pathogenesis of spirochaetes. Because spirochaete lipobox sequences exhibit more plasticity than those of other bacteria, application of existing prediction algorithms to emerging sequence data has been problematic. In this paper a novel lipoprotein prediction algorithm is described, designated SpLip, constructed as a hybrid of a lipobox weight matrix approach supplemented by a set of lipoprotein signal peptide rules allowing for conservative amino acid substitutions. Both the weight matrix and the rules are based on a training set of 28 experimentally verified spirochaetal lipoproteins. The performance of the SpLip algorithm was compared to that of the hidden Markov model-based LipoP program and the rules-based algorithm Psort for all predicted protein-coding genes of Leptospira interrogans sv. Copenhageni, L. interrogans sv. Lai, Borrelia burgdorferi, Borrelia garinii, Treponema pallidum and Treponema denticola. Psort sensitivity (13-35%) was considerably less than that of SpLip (93-100%) or LipoP (50-84%) due in part to the requirement of Psort for Ala or Gly at the -1 position, a rule based on E. coli lipoproteins. The percentage of false-positive lipoprotein predictions by the LipoP algorithm (8-30%) was greater than that of SpLip (0-1%) or Psort (4-27%), due in part to the lack of rules in LipoP excluding unprecedented amino acids such as Lys and Arg in the -1 position. This analysis revealed a higher number of predicted spirochaetal lipoproteins than was previously known. The improved performance of the SpLip algorithm provides a more accurate prediction of the complete lipoprotein repertoire of spirochaetes. The hybrid approach of supplementing weight matrix scoring with rules based on knowledge of protein secretion biochemistry may be a general strategy for development of improved prediction algorithms.

The first and, to date, only extrachromosomal circular replicon identified in the spirochete Leptospira is the LE1 prophage from Leptospira biflexa. The 74-kb LE1 genome has a GC content of 36%, which is similar to the GC content of Leptospira spp. Most of the 79 predicted open reading frames (ORFs) showed no similarities to known ORFs. However 21 ORFs appeared to be organized in clusters that could code for head and tail structural proteins and immunity repressor proteins. In addition, the pattern of gene expression showed that several LE1 genes are expressed specifically either in LE1 prophage or in L. biflexa late after infection. Since the LE1 prophage replicates autonomously as a circular replicon in L. biflexa, we were able to engineer an L. biflexa-Escherichia coli shuttle vector from a g.3-kb DNA fragment of LE1 (Saint Girons et al., J. Bacteriol. 182:5700-5705, 2000), opening this genu to genetic manipulation. In this study, base compositional asymmetry confirms the location of the LE1 replication region and suggests that LE1 replicates via a bidirectional [THETA]-like replication mechanism from this unique origin. By subcloning experiments, the replication region can be narrowed down to a 1-kb region. This minimal replication region consists of a rep encoding a protein of 180 amino acids. Upstream from rep, putative partitioning genes, called parA and parB, were found to be similar to the par loci in Borrelia plasmids. A significant increase of plasmid stability in L. biflexa can be seen only when both parA and parB are present. These results enable the construction of new shuttle vectors for studying the genetics of Leptospira spp. This study will also contribute to a better knowledge of phages unrelated to lambdoid phages.

Comparative 16S rRNA sequence analysis and fluorescence in situ hybridization (FISH) is used to examine the diversity and phylogeny of symbionts in two geographically separated Olavius crassitunicatus populations from the Peru margin. A phylogenetically diverse symbiont population consisting of five or six co-occurring bacterial phylotypes is discovered, which appear to be highly specific and stable in both host populations.

Factor H and factor H like-protein 1 (FHL-1) are complement regulatory proteins that serve as cofactors for the factor I-mediated cleavage of C3b. Some Lyme disease and relapsing fever spirochete species bind factor H to their surface to facilitate immune evasion. The Lyme disease spirochetes produce several factor H binding proteins (FHBPs) that form two distinct classes. Class I FHBPs (OspE orthologs and paralogs) bind only factor H, while class II FHBPs (BBA68) bind both factor H and FHL-1. BBA68 belongs to a large paralogons protein family, and of these paralogs, BBA69 is the member most closely related to BBA68. To determine if BBA69 can also bind factor H, recombinant protein was generated and tested for factor H binding. BBA69 did not exhibit factor H binding ability, suggesting that among family 54 paralogs, factor H binding is unique to BBA68. To identify the determinants of BBA68 that are involved in factor H binding, truncation and site-directed mutational analyses were performed. These analyses revealed that the factor H binding site is discontinuous and provide strong evidence that coiled-coil structural elements are involved in the formation of the binding site.

Spirochetes in the genus Borrelia carry a linear chromosome and numerous linear plasmids that have covalently closed hairpin telomeres. The overall organization of the large chromosome of Borrelia burgdorferi appears to have been quite stable over recent evolutionary time; however, a large fraction of natural isolates carry differing lengths of DNA that extend the right end of the chromosome between about 7 and 20 kbp relative to the shortest chromosomes. We present evidence here that a rather recent nonhomologous recombination event in the B. burgdorferi strain Sh-2-82 lineage has replaced its right chromosomal telomere with a large portion of the linear plasmid lp21, which is present in the strain B31 lineage. At least two successive rounds of addition of linear plasmid genetic material to the chromosomal right end appear to have occurred at the Sh-2-82 right telomere, suggesting that this is an evolutionary mechanism by which plasmid genetic material can become part of the chromosome. The unusual nonhomologous nature of this rearrangement suggests that, barring horizontal transfer, it can be used as a unique genetic marker for this lineage of B. burgdorferi chromosomes.

Certain oral treponemes express a highly proteolytic phenotype and have been associated with periodontal diseases. The periodontal pathogen Treponema denticola produces dentilisin, a serine protease of the subtilisin family. The two-gene operon prcA-prtP is required for expression of active dentilisin (PrtP), a putative lipoprotein attached to the treponeme's outer membrane or sheath. The purpose of this study was to examine the diversity and structure of treponemal subtilisin-like proteases in order to better understand their distribution and function. The complete sequences of five prcA.prtP operons were determined for Treponema lecithinolyticum, 'Treponema vincentii,' and two canine species. Partial operon sequences were obtained for T. socranskii subsp. 04 as well as 450- to 1,000-base fragments of prtP genes from four additional treponeme strains. Phylogenetic analysis demonstrated that the sequences fall into two paralogous families. The first family includes the sequence from T. denticola. Treponemes possessing this operon family express chymotrypsin-like protease activity and can cleave the substrate N-succinyi-alanyl-alanyl-prolyl-phenylalanine-p-nitroa. nilide (SAAPFNA). Treponemes possessing the second paralog family do not possess chymotrypsin-like activity or cleave SAAPFNA. Despite examination of a range of protein and peptide substrates, the specificity of the second protease family remains unknown. Each of the fully sequenced prcA and prtP genes contains a 5' hydrophobic leader sequence with a treponeme lipobox. The two paralogous families of treponeme subtilisins represent a new subgroup within the subtilisin family of proteases and are the only subtilisin lipoprotein family. The present study demonstrated that the subtilisin paralogs comprising a two-gene operon are widely distributed among treponemes.

The tprK gene of Treponema pallidum subsp. pallidum, the causative agent of venereal syphilis, belongs to a 12-member gene family and encodes a protein with a predicted cleavable signal sequence and predicted transmembrane domains. Except for the Nichols type strain, all rabbit-propagated isolates of T. pallidum examined thus far are comprised of mixed populations of organisms with heterogeneous tprK sequences. We show that tprK sequences in treponemes obtained directly from syphilis patients are also heterogeneous. Clustering analysis demonstrates that primary chancre tprK sequences are more likely to cluster within a sample than among samples and that tighter clustering is seen within chancre samples than within rabbit-propagated isolates. Closer analysis of tprK sequences from a rabbit-propagated isolate reveals that individual variable regions have different levels of diversity, suggesting that variable regions may have different intrinsic rates of sequence change or may be under different levels of selection. Most variable regions show increased sequence diversity upon passage. We speculate that the diversification of tprK during infection allows organisms to evade the host immune response, contributing to reinfection and persistent infection.

The hindguts of wood-feeding termites are the sites of intense, C[O.sub.2]-reductive acetogenesis. This activity profoundly influences host nutrition and methane emissions. Homoacetogens previously isolated from diverse termites comprised novel taxa belonging to two distinct bacterial phyla, Firmicutes and Spirochaetes. Little else is known about either the diversity or abundance of homoacetogenic species present in any given termite or the genetic details underlying C[O.sub.2]-reductive acetogenesis by Spirochaetes. A key enzyme of C[O.sub.2]-reductive acetogenesis is formyltetrahydrofolate synthetase (FTHFS). A previously designed primer set was used to amplify FTHFS genes from three isolated termite-gut spirochaetes. Sequencing DNA flanking the FTHFS gene of Treponema strain ZAS-2 revealed genes encoding two acetogenesis-related enzymes, methenyltetrahydrofolate cyclohydrolase and methylenetetrahydrofolate dehydrogenase. Although termite-gut spirochaetes are only distantly related to clostridia at the ribosomal level, their tetrahydrofolate-dependent enzymes appear to be closely related. In contrast, homologous proteins identified in the non-homoacetogenic oral spirochaete Treponema denticola were only distantly related to those from clostridia and the termite-gut treponemes. Having demonstrated their utility with spirochaete pure cultures, the FTHFS primers were used to construct a 91-clone library from the termite-gut community DNA. From this, 19 DNA and eight amino acid FTHFS types were identified. Over 75% of the retrieved clones formed a novel, coherent cluster with the FTHFS homologues obtained from the termite-gut treponemes. Thus, FTHFS gene diversity in the gut of the termite Zootermopsis angusficollis appears to be dominated by spirochaetes. The homoacetogenic capacity of termite-gut spirochaetes may have been acquired via lateral gene transfer from clostridia.

A novel, fast-growing spirochaete was isolated from the hard tick Hyalomma aegyptium (family Ixodidae, subfamily Metastriata) using Barbour-Stoenner --Kelly (BSK) II medium. Tick samples were taken during the summer of 2000 from the Istanbul area in northwestern Turkey. Sixty-seven of 153 adults (44 %) and 72 of 185 nymphs (39 %) were infected with the novel spirochaete, whereas none of the 20 larvae examined were infected. The optimal growth temperature of the spirochaete in BSK II medium was 34-37[degrees]C, and it could grow at 39 [degrees]C. Doubling times at 34 and 37[degrees]C were 5.3 and 5.1 h, respectively. Six pure cultures of the spirochaete were obtained and characterized by microscopic observation, sequence analysis of the flagellin gene (flaB), SDS-PAGE and Western blotting. The spirochaete was morphologically similar to those of the genus Borrelia and contained a 41 kDa protein reactive with mAb H9724 specific to the flagellin of a Borrelia species. Polyclonal antibody raised to this spirochaete reacted with several antigen bands, whereas no bands were detected with Borrelia burgdorferi, Borrelia hermsii, Borrelia turicatae and Borrelia parkeri. The flaB sequences of the six isolates showed high similarity, with sequence similarity values ranging from 99.2 to 100%; however, the similarity of the isolates' flaB sequences to those of the Lyme-disease-related Borrelia and relapsing-fever-associated Borrelia species was less than 90%. These findings suggest that the unique spirochaete is a member of the genus Borrelia, and differs from previously described Borrelia species.

DNA microarrays were used to survey the adaptive genetic responses of Borrelia burgdorferi (Bb) B31, the Lyme disease spirochete, when grown under conditions analogous to those found in unfed ticks (UTs), fed ticks (FTs), or during mammalian host adaptation (Bb in dialysis membrane chambers implanted in rats). Microarrays contained 95.4% of the predicted B31 genes, 150 (8.6%) of which were differentially regulated (changes of [greater than or equal to] 1.8-fold) among the three growth conditions. A substantial proportion (46%) of the differentially regulated genes encoded proteins with predicted export signals (29% from predicted lipoproteins), emphasizing the importance to Bb of modulating its extracellular proteome. For B31 cultivated at the more restrictive UT condition, microarray data provided evidence of a bacterial stringent response and factors that restrict cell division. A large proportion of genes were responsive to the FT growth condition, wherein increased temperature and reduced pH were prominent environmental parameters. A surprising theme, supported by cluster analysis, was that many of the gene expression changes induced during the FT growth condition were transient and largely tempered as B31 adapted to the mammalian host, suggesting that once Bb gains entry and adapts to mammalian tissues, fewer differentially regulated genes are exploited. It therefore would seem that although widely dissimilar, the UT and dialysis membrane chamber growth conditions promote more static patterns of gene expression in Bb. The microarray data thus provide a basis for formulating new testable hypotheses regarding the life cycle of Bb and attaining a more complete understanding of many aspects of Bb's complex parasitic strategies.

Mutational analysis reveals that in Leptospira biflexa, RecA mediates cell viability through DNA repair and chromosome partitioning.

Mutants of treponema denticola, defective in the synthesis of cytoplasmic filament, exhibit pleiotrophy in terms of highly condensed chromosomal DNA, formation of cells in chain, and abnormal cell lengths. Data suggest that the cytoplasmic filaments may influence chromosome structure, segregation, or cell division.

Research has been conducted on the spirochete FlaA periplasmic flagellar (PFs). The construction of mutants flaB2 and flaB3 has been carried out to analyze their purified PFs and the results indicate that the inactivation of one of the genes inhibits the incorporation of the encoded protein into the assembled PF.

Research was conducted to clone and characterize a gene encoding the major sheath protein of Treponema maltophium ATCC 51939T. Cloning was carried out by screening a genomic library with an anti-outer membrane fraction antibody. The MspA gene formed a heat-modifiable, detergent- and trypsin-stable complex that is associated with the outer membrane. Results demonstrate that hybridization with an msp-A-specific probe yielded no cross-reactivity with the msp gene from Treponema denticola.

Oligonucleotide primers derived from the ATCC 35405 msp locus of Treponema denticola ATCC 35405 were utilized to identify and characterize msp sequences from the genomic DNA of several Treponema strains. Analysis of several Treponema spp. strains representing three different serotypes indicated the presence of a highly conserved msp gene in all the strains. Furthermore, the msp gene from the Treponema strains was flanked by sequences that were homologous to the proposed transcription promoter and terminator of the ATCC 35405 msp gene.

The VSH-1 mitomycin-inducible phage from Serpulina hyodysenteriae was purified and characterized to determine the ability of the phage to transduce specific genes in the spirochete. The isolated Serpulina hyodysenteriae bacteriophage exhibited a morphology that was similar to the tailed phages of the Siphoviridae family. The VSH-1 was also incapable of lytic growth and was nonlytic due to a packaging defect.

Southern blot analysis was utilized to characterize the seven 32-kilodalton circular plasmids of Borrelia burgdorferi B31 isolates to determine the occurrence of the 32-kilodalton circular plamids in Lyme disease spirochetes. Restriction endonuclease recognition site mapping indicated the presence of similar and closely related regions in the seven 32-kilodalton circular plasmids of Borrelia burgdorferi. Furthermore, all isolates of Borrelia burgdorferi and related borreliae contained at least one or more plasmids that were related to the 32-kilodalton circular plasmids.

The oral spirochete Treponema denticola has been confirmed in previous studies to carry potential virulence factors for periodontitis. Using a gene transfer system, it is shown that the T. denticola flgE gene coding for the flagellar hook protein affects motility. Insertion of an flgE mutant into an flgE DNA fragment abolished motility and prevented the formation of periplasmic flagella.

Cloning and expression of the ospE and ospF genes of the pathogenic bacteria Borrelia burgdorferi B31 identified six different proteins encoded by genes related to ospE and ospF. Sequence analysis showed that these genes are located in four separate loci, with each havin an extended DNA sequence that is highly similar to that located upstream of the ospEF operon of B. burgdorferi N40.

The 5' terminal region of the msp gene of spirochete Treponema denticola contains an open reading frame of 1,629 bp that encodes the major outer sheath protein (Msp). The encoded peptide contains 543 residues, and its molecular mass is 58,233 Da. It has a prokaryotic signal sequence and a signal peptidase I cleavage site. The Msp expression is lethal for Escherichia coli in the presence of the whole msp gene. The recombinant Msp binds to immobilized laminin and fibronectin. Soluble substrates decrease the binding, while pretreatment with recombinant Msp increases it.

Characterization of the genomic organization of spirochetes of the genus Borrelia by pulsed-field gel electrophoresis revealed a linear chromosome about 1 Mb in size and multiple linear plasmids in the 16- to 200-kb size range. Two forms of plasmids were observed, linear and circular. The shape of the plasmids had no effect on the behavior of the species bearing either form of the plasmids. However, conversion from the linear form to the circular form of the plasmid was observed in the relapsing fever agent B. hermsii.

Forty intestinal spirochaete strains were investigated for nucleotide sequences related to the smpA locus from Serpulina hyodysenteriae by Southern hybridization of chromosomal DNA using the smpA locus from S. hyodysenteriae strain P18A as a probe and by PCR using primers internal to the smpA gene. The intensity of the hybridization signal at high stringency and positive PCR results suggested that 12 S. hyodysenteriae strains possessed a similar nucleotide sequence. PCR was negative for another 12 S. hyodysenteriae strains and the hybridization signal obtained from 11 of these was weak and one was negative. All S. hyodysenteriae strains hybridized under low stringency conditions. These results indicated that there is variation among the smpA loci of S. hyodysenteriae strains. Among seven strains of S. innocens, and the proposed species 'S. intermedius' and 'S. murdochii', hybridization was weak and no PCR products were obtained, suggesting that these species have sequences related to, but divergent from, the smpA sequences of strains of S. hyodysenteriae. Both gene probe hybridization and PCR analysis of nine strains of the proposed new genus' Anguillina', including isolates from pigs and humans, gave negative results. Keywords: swine dysentery, Serpulina hyodsenteriae, smpA gene, intestinal spirochaetes, PCR

Cloned ospC genes of the outer surface protein (OspC) from 22 Borrelia burgdorferi strains revealed 48 amino acids. A comparison of the amino acid sequences with the ospC nucleotide sequences previously reported classified the ospC sequences into three major groups. The first contained ospC alleles from sensu stricto strains, the second group contained ospC alleles from Borrelia afzelii strains and the third group contained ospC alleles from five B. afzilii and all B. garinii strains. The results provide evidences for the phylogenetic relationship of the Borrelia species.

All the tested 22 isolates of the Borellia species which cause Lyme's disease had similar linear chromosomes and contained a large number of linear plasmids. The chromosomal gene order was highly conserved but the chromosomal restriction endonuclease cleavage site maps were different for each isolate. Nucleotide sequences in the chromosomes also show differences but the gene action for all the isolates is almost identical.

Analysis of nucleotide sequences of a circular plasmid from the spirochete, Borrelia burgdorferi reveals the presence of RC plasmids that replicate by a rolling circle mechanism, initiated by the replication protein, RepC. The plasmid has a 184 bp inverted repeat sequence and clsely-packed open reading frames. This plasmid can be used as a vector for gene transfer in Borrelia.

Automated PCR-directed cycle sequencing was used to determine the 16S rDNA sequences from 15 Leptospiraceae. Phylogenetic trees were developed to reveal that Serpulina hyodysenteriae and S. innocens are linked but differed from the heptospiraceae. The pathogenic and saprophytic Leptospires differed from each other. The pathogens comprised three groups while the freshwater isolates differed from the marine isolates, L.biflexa sensu lato ancona Ancona Porto.

Genetic maps for two Leptospira interrogans serovars, pomona and icterohaemorrhagiae, reveal that both the replicons of the genomes of serovars are chromosomes, and that there is intraspecies heterogeneity in L. interrogans. Different animal host species contain these serovars, and they are revealed to be genetically identical by DNA homology experiments. The genetic organizations and physical maps of the serovars are not similar. A large and a small replicon comprise the genomes of both serovars, and the majority of the important genes are found in the larger replicon.

The cloning, characterization and nucleotide sequence of the leuB gene of Leptospira interrogans serovar pomona were reported. The gene complements a leuB defect in Escherichia coli. It was shown that the product of the cloned gene was a beta-isopropylmalate dehydrogenase. Maxicell analysis revealed that three proteins were encoded and that a 42 kDa protein was required for complementation of the leuB defect. The sequence data indicate that the organization of the leucine biosynthetic genes in L. interrogans differs from that found in other bacteria.

To the Editor: Tick-borne relapsing fever (TBRF) is caused by infection with spirochetes belonging to the genus Borrelia. We previously reported a human case of febrile illness suspected to be [...]

The Brachyspira hyodysenteriae B204 genome sequence revealed three VSH-1 tail genes, hvp31, hvp60, and hvp37, in a 3.6-kb cluster. The location and transcription direction of these genes relative to those of the previously described VSH-1 16.3-kb gene operon indicate that the gene transfer agent VSH-1 has a noncontiguous, divided genome.

The restriction enzyme RsaI, which recognizes the sequence 5'-GTAC, was used to digest the genomic DNA of seven species of Leptospira. The Leptospira genomes were resistant to RsaI cleavage. This was attributed to a DNA modification that methylates the C base of 5'-GTAC. Statistical analysis was conducted to determine the number of modified 5'-GTAC sites. The analysis showed that the distribution of the modification is not typical of a conventional restriction-modification system.

Several studies are conducted to explain the population structure of the lyme borreliosis spirochete, Borrelia burgdorferi, present in the western black-legged tick in Northern California. The different factors that lead to the observed diversity in the structure and pattern are also discussed.

The development of a successful modified Himar1 transposon mutagenesis in the oral spirochete Treponema denticola is reported. The random mutagenesis system can be used for carrying out research on the biology and pathogenesis of spirochete associated with human periodontal diseases.

The paper presents the mutants in the distal rod of flagellum protein and the growth of flagella as in spirochetes. Outer membrane penetration shows efficient coupling.

A study was conducted on a novel spirochete strain, SPN1, after isolating it from the hindgut contents of the Neotermes castaneus. It was observed that the SPN1 might play an important role in the digestion of breakdown products from cellulose and hemicellulose in the termite gut.

Research has been conducted on paralogous genes bapA and eppA found in Lyme disease spirochaete isolates. The results of immunological analysis of serum samples have demonstrated that bapA gene sequences are stable but the encoded BarA proteins do not provoke strong immunological response, and that EppA proteins are much more antigenic but have different sequence between different bacteria.

Research has been conducted on oral-related human Treponema. The authors demonstrate that Treponema have broad host specificity, and that preventive strategies have to be developed for both human and animal Treponema-associated infections.

Research has been conducted on Borrelia species. The investigation of these species in studying glycerophosphodiester phosphodiesterase activity and in examining glp locus at the DNA level is described.

The genome of Borrelia burgdorferi encodes a large number of lipoproteins, many of which are expressed only at certain stages of the spirochete's life cycle. In the current study we describe the B. burgdorferi population structure with respect to the production of two lipoproteins [outer surface protein A (OspA) and outer surface protein C (OspC)] during transmission from the tick vector to the mammalian host. Before the blood meal, the bacteria in the tick were a homogeneous population that mainly produced OspA only. During the blood meal, the population became more heterogeneous; many bacteria produced both OspA and OspC, whereas others produced only a single Osp and a few produced neither Osp. From the heterogeneous spirochetal population in the gut, a subset depleted of OspA entered the salivary glands and stably infected the host at time points [is greater than] 53 hr into the blood meal. We also examined genetic heterogeneity at the B. burgdorferi vise locus before and during the blood meal. In unfed ticks, the vise locus was stable and one predominant and two minor alleles were detected. During the blood meal, multiple vise alleles were observed in the tick. Tick feeding may increase recombination at the vise locus or selectively amplify rare vise alleles present in unfed ticks. On the basis of our data we propose a model, which is different from the established model for B. burgdorferi transmission. Implicit in our model is the concept that tick transmission converts a homogeneous spirochete population into a heterogeneous population that is poised to infect the mammalian host.

Spirochaeta thermophila is a thermophilic, free-living anaerobe that is able to degrade various [alpha]- and [beta]-1inked sugar polymers, including cellulose. We report here the complete genome sequence of S. thermophila DSM 6192, which is the first genome sequence of a thermophilic, free-living member of the Spirochaetes phylum. The genome data reveal a high density of genes encoding enzymes from more than 30 glycoside hydrolase families, a noncellulosomal enzyme system for (hemi)cellulose degradation, and indicate the presence of a novel carbohydrate-binding module. doi: 10.1128/JB.01023-10