Recombinational basis of serovar diversity in Salmonella enterica.

Li, Jia; Nelson, Kimberlyn; McWhorter, Alma C.; Whittam, Thomas S.; Selander, Robert K.

doi:10.1073/pnas.91.7.2552

Cited by 88 publications

(63 citation statements)

References 41 publications

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“…All sequences were highly conserved at the extreme 5Ј and 3Ј ends and diverged, with respect to other alleles, as they approached the middle, variable portion of the gene. Conserved and variable regions were consistent with previous designations (15,29).…”

Section: Resultssupporting

confidence: 67%

“…Sequences within the ␣ cluster had Ͼ89% amino acid sequence identity, but this number rose to greater than 94% amino acid sequence identity when the most divergent antigens (flagellar antigens b and d) were removed from the analysis. Li and colleagues (15) noted that flagellar antigen g,z 51 clustered separately from the rest of the G complex; when g,z 51 alleles were removed from the analysis, the G complex alleles had greater than 98% amino acid identity in the conserved region. In contrast, there was 73 to 87% amino acid identity between the groups, which is on the order of the sequence identity with representative E. coli fliC sequences from GenBank release 132.…”

Section: Vol 42 2004 Analysis Of Flagellin Genes Of Salmonella 1927mentioning

confidence: 99%

“…The conserved regions encode the flagellar filament backbone and are critical for the assembly of the filament. The central region, corresponding approximately to amino acids 181 to 390, encodes the surface-exposed and antigenically variable portion of the filament (13)(14)(15)29). Several studies have reported DNA sequences for Salmonella flagellin genes (6,11,13,15,17,24,25,27,29).…”

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confidence: 99%

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Sequencing and Comparative Analysis of Flagellin Genes fliC , fljB , and flpA from Salmonella

et al. 2004

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Salmonella isolates have traditionally been classified by serotyping, the serologic identification of two surface antigens, O-polysaccharide and flagellin protein. Serotyping has been of great value in understanding the epidemiology of Salmonella and investigating disease outbreaks; however, production and quality control of the hundreds of antisera required for serotyping is difficult and time-consuming. To circumvent the problems associated with antiserum production, we began the development of a system for determination of serotype in Salmonella based on DNA markers. To identify flagellar antigen-specific sequences, we sequenced 280 alleles of the three genes that are known to encode flagellin in Salmonella, fliC, fljB, and flpA, representing 67 flagellar antigen types. Analysis of the data indicated that the sequences from fliC, fljB, and flpA clustered by the antigen(s) they encode not by locus. The sequences grouped into four clusters based on their conserved regions. Three of the four clusters included multiple flagellar antigen types and were designated the G complex, the Z4 complex, and the ␣ cluster. The fourth cluster contained a single antigen type, H:z 29 . The amino acid sequences of the conserved regions within each cluster have greater than 95% amino acid identity, whereas the conserved regions differ substantially between clusters (75 to 85% identity). Substantial sequence heterogeneity existed between alleles encoding different flagellar antigens while alleles encoding the same flagellar antigen were homologous, suggesting that flagellin genes may be useful targets for the molecular determination of flagellar antigen type.

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Section: Resultssupporting

confidence: 67%

Section: Vol 42 2004 Analysis Of Flagellin Genes Of Salmonella 1927mentioning

confidence: 99%

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confidence: 99%

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Sequencing and Comparative Analysis of Flagellin Genes fliC , fljB , and flpA from Salmonella

et al. 2004

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“…The ratios of d S between the two regions in the B. garinii and B. afzelii alleles are 2.9 and 3.9, respectively. The simplest explanation for these elevated d S values would be recombination between distantly related sequences (15,20).…”

Section: Discussionmentioning

confidence: 99%

Evolution of the Borrelia burgdorferi outer surface protein OspC

et al. 1995

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The genes coding for outer surface protein OspC from 22 Borrelia burgdorferi strains isolated from patients with Lyme borreliosis were cloned and sequenced. For reference purposes, the 16S rRNA genes from 17 of these strains were sequenced after being cloned. The deduced OspC amino acid sequences were aligned with 12 published OspC sequences and revealed the presence of 48 conserved amino acids. On the basis of the alignment, OspC could be divided into an amino-terminal relatively conserved region and a relatively variable region in the central portion. The distance tree obtained divided the ospC sequences into three groups. The first group contained ospC alleles from all (n ‫؍‬ 13) sensu stricto strains, the second group contained ospC alleles from seven Borrelia afzelii strains, and the third group contained ospC alleles from five B. afzelii and all (n ‫؍‬ 9) Borrelia garinii strains. The ratio of the mean number of synonymous (d S ) and nonsynonymous (d N ) nucleotide substitutions per site calculated for B. burgdorferi sensu stricto, B. garinii, and B. afzelii ospC alleles suggested that the polymorphism of OspC is due to positive selection favoring diversity at the amino acid level in the relatively variable region. On the basis of the comparison of 16S rRNA gene sequences, Borrelia hermsii is more closely related to B. afzelii than to B. burgdorferi sensu stricto and B. garinii. In contrast, the phylogenetic tree obtained for the B. hermsii variable major protein, Vmp33, and 18 OspC amino acid sequences suggested that Vmp33 and OspC from B. burgdorferi sensu stricto strains share a common evolutionary origin.The outer membrane protein OspC is an immunodominant surface protein of the spirochete Borrelia burgdorferi, which causes Lyme borreliosis. The first detectable antibody response to B. burgdorferi consists of immunoglobulin M antibodies to OspC as well as to the 41-kDa flagellin (29). Thus, OspC, like the flagellum (9), may become an important diagnostic antigen.The OspC protein is also considered a vaccine candidate, since active immunization with recombinant OspC protected gerbils (22) and mice (23) against subsequent challenge with the homologous B. burgdorferi strain. Moreover, protection against B. burgdorferi challenge was observed in recent studies involving hamsters immunized with a mutant of strain 297 expressing ospC but lacking OspA and OspB (12). These findings strongly suggest that a Lyme borreliosis vaccine may benefit from inclusion of OspC in conjunction with other antigens.Significant heterogeneity exists in OspC at the immunological level (25,28) and at the genetic level (13,17,25). On the basis of the analysis of the nucleotide sequences from seven B. burgdorferi strains, we found that ospC sequences fall into three groups, each corresponding to one of the genospecies B. burgdorferi sensu stricto, Borrelia garinii, and Borrelia afzelii (25).In order to further investigate the evolution of the ospC locus, ospC genes from 22 B. burgdorferi strains were cloned and sequenced and compared...

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“…Comparison of scattered chromosomal restriction endonuclease cleavage site locations in closely related bacteria is a valuable way to obtain information on the overall extent of genetic variation within a species and between closely related species (e.g., see references 12, 14, 16, 17, 33, 34, and 71). This approach is different from comparison of nucleotide sequences from single loci (35,45), since it samples short nucleotide sequences (the enzyme recognition sites) across the length of the chromosome. In order to more clearly define the genetic variation among and within the different types of Lyme disease agent bacteria, we present and compare restriction endonuclease cleavage site maps of the chromosomes of the following 22 isolates: 7 geographically diverse B. burgdorferi, 3 B. garinii, 3 B. afzelii, 2 B. japonica, and 7 other isolates whose relationships to the four previously defined types were ambiguous.…”

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confidence: 99%

Linear chromosomes of Lyme disease agent spirochetes: genetic diversity and conservation of gene order

et al. 1995

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We have constructed physical and genetic maps of the chromosomes of 21 Lyme disease agent spirochetes from geographically diverse locations. All have linear chromosomes whose lengths range from 935 to 955 kbp, and all contain multiple linear plasmids in the 16-to 175-kbp size range. The locations of 11 gene clusters on the chromosomes of these different isolates are indistinguishable at the resolution achieved in this study, indicating that the members of this related group of species have highly conserved chromosomal gene orders. However, chromosomal restriction endonuclease cleavage site maps are unique for nearly all isolates. The 22 chromosomal maps currently available define eight classes of Lyme disease agents. Four of these correspond to the previously proposed species Borrelia burgdorferi, Borrelia garinii, Borrelia afzelii, and Borrelia japonica. In addition, the North American isolates 21038, DN127 cl9-2, 25015, and CA55 typify four additional chromosomal types that are as phylogenetically distinct as the species listed above. These findings support the idea that comparison of restriction maps is currently the most robust and definitive method for determining overall chromosomal relationships among closely related bacteria. In the course of this work, we located on the chromosome the previously unmapped outer surface protein-encoding LA7 gene and genes homologous to the Escherichia coli priA, plsC, parE, and parC genes, and we have substantially refined the locations of the recA, fla, p22A, and flgE genes.

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Recombinational basis of serovar diversity in Salmonella enterica.

Cited by 88 publications

References 41 publications

Sequencing and Comparative Analysis of Flagellin Genes fliC , fljB , and flpA from Salmonella

Sequencing and Comparative Analysis of Flagellin Genes fliC , fljB , and flpA from Salmonella

Evolution of the Borrelia burgdorferi outer surface protein OspC

Linear chromosomes of Lyme disease agent spirochetes: genetic diversity and conservation of gene order

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