SEARCH · PubMed Health

Results for “Multilocus sequence typing”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources

PubMed1999

Diversity of rhizobia associated with Amorpha fruticosa isolated from Chinese soils and description of Mesorhizobium amorphae sp. nov.

Fifty-five Chinese isolates from nodules of Amorpha fruticosa were characterized and compared with the type strains of the species and genera of bacteria which form nitrogen-fixing symbioses with leguminous host plants. A polyphasic approach, which included RFLP of PCR-amplified 16S rRNA genes, multilocus enzyme electrophoresis (MLEE), DNA-DNA hybridization, 16S rRNA gene sequencing, electrophoretic plasmid profiles, cross-nodulation and a phenotypic study, was used in the comparative analysis. The isolates originated from several different sites in China and they varied in their phenotypic and genetic characteristics. The majority of the isolates had moderate to slow growth rates, produced acid on YMA and harboured a 930 kb symbiotic plasmid (pSym). Five different RFLP patterns were identified among the 16S rRNA genes of all the isolates. Isolates grouped by PCR-RFLP of the 16S rRNA genes were also separated into groups by variation in MLEE profiles and by DNA-DNA hybridization. A representative isolate from each of these DNA homology groups had a separate position in a phylogenetic tree as determined from sequencing analysis of the 16S rRNA genes. A new species, Mesorhizobium amorphae, is proposed for the majority of the isolates, which belonged to a moderately slow- to slow-growing, acid-producing group based upon their distinct phylogenetic position, their unique electrophoretic type, their low DNA homology with reference strains representing the species within the genus Mesorhizobium and their distinct phenotypic features. Strain ACCC 19665 was chosen as the type strain for M. amorphae sp. nov.

Base Composition↗

PubMed2003

Population genetics of Vibrio vulnificus: identification of two divisions and a distinct eel-pathogenic clone.

Genetic relationships among 62 Vibrio vulnificus strains of different geographical and host origins were analyzed by multilocus enzyme electrophoresis (MLEE), random amplification of polymorphic DNA (RAPD), and sequence analyses of the recA and glnA genes. Out of 15 genetic loci analyzed by MLEE, 11 were polymorphic. Cluster analysis identified 43 distinct electrophoretic types (ETs) separating the V. vulnificus population into two divisions (divisions I and II). One ET (ET 35) included all indole-negative isolates from diseased eels worldwide (biotype 2). A second ET (ET 2) marked all of the strains from Israel isolated from patients who handled St. Peter's fish (biotype 3). RAPD analysis of the 62 V. vulnificus isolates identified 26 different profiles separated into two divisions as well. In general, this subdivision was comparable (but not identical) to that observed by MLEE. Phylogenetic analysis of 543 bp of the recA gene and of 402 bp of the glnA gene also separated the V. vulnificus population into two major divisions in a manner similar to that by MLEE and RAPD. Sequence data again indicated the overall subdivision of the V. vulnificus population into different biotypes. In particular, indole-negative eel-pathogenic isolates (biotype 2) on one hand and the Israeli isolates (biotype 3) on the other tended to cluster together in both gene trees. None of the methods showed an association between distinct clones and human clinical manifestations. Furthermore, except for the Israeli strains, only minor clusters comprising geographically related isolates were observed. In conclusion, all three approaches (MLEE, RAPD, and DNA sequencing) generated comparable but not always equivalent results. The significance of the two divisions (divisions I and II) still remains to be clarified, and a reevaluation of the definition of the biotypes is also needed.

Animals↗

PubMed1993

Typing by serovar, antibiogram, plasmid content, riboprobing, and isoenzyme typing to determine whether Neisseria gonorrhoeae isolates requiring proline, citrulline, and uracil for growth are clonal.

Neisseria gonorrhoeae isolates requiring proline, citrulline, and uracil for growth (PCU-) have homogeneous phenotypes; most are plasmid-free, belong to few serovars, and are significantly associated with intermediate levels of susceptibility to penicillin, tetracycline, erythromycin, and cefoxitin. Because of their lack of variation by these criteria, molecular typing methods, ribotyping (restriction fragment length polymorphism [RFLP] of rRNA genes), and multilocus enzyme electrophoresis were explored as tools for further distinguishing PCU- isolates. By ribotyping, selected PCU- isolates could be separated into four groups on the basis of the hybridization patterns (RFLPs) of SmaI- and AvaII-digested DNA with probes containing rRNA sequences. Most of the isolates (18 of 23 isolates) belonged to a single RFLP (group I). One isolate each was in groups II and IV, and three isolates were in group III. All isolates except one, isolate NS791, had similar multilocus enzyme electrophoresis patterns. Strain NS791 was unusual in that it contained a variant cryptic plasmid with an insert in the 0.46-kb MspI-HinfI fragment of the 4.2-kb plasmid, it was the only isolate belonging to RFLP group IV, and it differed in its multilocus enzyme electrophoresis pattern, having different mobilities for glyceraldehyde phosphate dehydrogenase, phosphoglucose isomerase, 6-phosphogluconate dehydrogenase, and glutamate dehydrogenase. Serovars of PCU- isolates appeared to be more indicative of strain divergence than RFLP or isoenzyme typing. Multilocus enzyme electrophoresis indicated that PCU- isolates are clonal.

Bacterial Typing Techniques↗

PubMed2003

Ethiopian soils harbor natural populations of rhizobia that form symbioses with common bean ( Phaseolus vulgaris L.).

The diversity and taxonomic relationships of 83 bean-nodulating rhizobia indigenous to Ethiopian soils were characterized by PCR-RFLP of the internally transcribed spacer (ITS) region between the 16S and 23S rRNA genes, 16S rRNA gene sequence analysis, multilocus enzyme electrophoresis (MLEE), and amplified fragment-length polymorphism. The isolates fell into 13 distinct genotypes according to PCR-RFLP analysis of the ITS region. Based on MLEE, the majority of these genotypes (70%) was genetically related to the type strain of Rhizobium leguminosarum. However, from analysis of their 16S rRNA genes, the majority was placed with Rhizobium etli. Transfer and recombination of the 16S rRNA gene from presumptively introduced R. etli to local R. leguminosarum is a possible theory to explain these contrasting results. However, it seems unlikely that bean rhizobia originating from the Americas (or Europe) extensively colonized soils of Ethiopia because Rhizobium tropici, Rhizobium gallicum, and Rhizobium giardinii were not detected and only a single ineffective isolate of R. etli that originated from a remote location was identified. Therefore, Ethiopian R. leguminosarum may have acquired the determinants for nodulation of bean from a low number of introduced bean-nodulating rhizobia that either are poor competitors for nodulation of bean or that failed to survive in the Ethiopian environment. Furthermore, it may be concluded from the genetic data presented here that the evidence for separating R. leguminosarum and R. etli into two separate species is inconclusive.

DNA Fingerprinting↗

PubMed1991

Rhizobium tropici, a novel species nodulating Phaseolus vulgaris L. beans and Leucaena sp. trees.

A new Rhizobium species that nodulates Phaseolus vulgaris L. and Leucaena spp. is proposed on the basis of the results of multilocus enzyme electrophoresis, DNA-DNA hybridization, an analysis of ribosomal DNA organization, a sequence analysis of 16S rDNA, and an analysis of phenotypic characteristics. This taxon, Rhizobium tropici sp. nov., was previously named Rhizobium leguminosarum biovar phaseoli (type II strains) and was recognized by its host range (which includes Leucaena spp.) and nif gene organization. In contrast to R. leguminosarum biovar phaseoli, R. tropici strains tolerate high temperatures and high levels of acidity in culture and are symbiotically more stable. We identified two subgroups within R. tropici and describe them in this paper.

Base Sequence↗

PubMed1996

Identification of IS1356, a new insertion sequence, and its association with IS402 in epidemic strains of Burkholderia cepacia infecting cystic fibrosis patients.

Burkholderia cepacia is now recognized as an important opportunistic pathogen in cystic fibrosis (CF) and other compromised patients. Epidemicity among CF patients has been attributed to at least one particularly infectious strain (strain ET12), and both genetic evidence and anecdotal evidence suggest that this strain, currently endemic in Ontario, and those causing an epidemic in the United Kingdom, are indeed the same. Our study was conducted to determine whether there was any association between the presence of various insertion sequence (IS) elements, the cable pilin subunit gene (cblA), electrophoretic type (ET), and ribotype (RT) in a collection of 97 clinical and 2 environmental isolates of B. cepacia. No apparent linkage was found for IS elements IS401, IS402, IS406, IS407, and IS408 with ET or RT. The cblA target, said to be a marker for high infectivity, was detected in 100% (38 of 38) of strains of B. cepacia ET12 and in a single strain of ET13 that differed in a single enzyme allele. A new IS, IS1356, identified during the investigation, was present in 71.7% of all isolates, and 50.7% of these isolates harbored IS1356 as a hybrid IS element inserted into IS402. IS1356 is 1,353 bp in length, and when it is inserted into IS402 it results in a 10-bp duplication at the site of insertion. IS1356 contains one major open reading frame of 1,260 bp coding for a putative transposase which has significant homology to ISRm3 in Rhizobium meliloti (59%) and to an undesignated IS element in Corynebacterium diphtheriae (49%). The IS402-IS1356 element was found exclusively in the epidemic strains from Ontario and the United Kingdom, being detected in 94.7% (36 of 38 isolates) of B. cepacia ET12 isolates. Of the two ET12 isolates found to be devoid of the IS402-IS1356 element, both contained IS1356 unassociated with IS402, one was temporally unrelated to the epidemic, and the other was from a CF patient in a geographic area remote from Ontario and the United Kingdom. It is evident that the IS402-IS1356 hybrid element, the cblA pilin subunit gene, and the allelic suite represented by multilocus enzyme electrophoretic type ET12 may provide useful markers for the epidemic, highly transmissible transatlantic strain isolated in Ontario and the United Kingdom.

Amino Acid Sequence↗

PubMed1992

Multilocus markers for mouse genome analysis: PCR amplification based on single primers of arbitrary nucleotide sequence.

Polymerase chain reaction (PCR) based on single primers of arbitrary nucleotide sequence provides a powerful marker system for genome analysis because each primer amplifies multiple products, and cloning, sequencing, and hybridization are not required. We have evaluated this typing system for the mouse by identifying optimal PCR conditions; characterizing effects of GC content, primer length, and multiplexed primers; demonstrating considerable variation among a panel of inbred strains; and establishing linkage for several products. Mg2+, primer, template, and annealing conditions were identified that optimized the number and resolution of amplified products. Primers with 40% GC content failed to amplify products readily, primers with 50% GC content resulted in reasonable amplification, and primers with 60% GC content gave the largest number of well-resolved products. Longer primers did not necessarily amplify more products than shorter primers of the same proportional GC content. Multiplexed primers yielded more products than either primer alone and usually revealed novel variants. A strain survey showed that most strains could be readily distinguished with a modest number of primers. Finally, linkage for seven products was established on five chromosomes. These characteristics establish single primer PCR as a powerful method for mouse genome analysis.

Animals↗

PubMed1991

Ionizing radiation and genetic risks. I. Epidemiological, population genetic, biochemical and molecular aspects of Mendelian diseases.

This paper reviews the currently available information on naturally occurring Mendelian diseases in man; it is aimed at providing a background and framework for discussion of experimental data on radiation-induced mutations (papers II and III) and for the estimation of the risk of Mendelian disease in human populations exposed to ionizing radiation (paper IV). Current consensus estimates indicate that a total of about 125 per 10(4) livebirths are directly affected by one or another naturally occurring Mendelian disease (autosomal dominants, 95/10(4); X-linked ones, 5/10(4); and autosomal recessives, 25/10(4). These estimates are conservative and take into account conditions which are very rare and for which prevalence estimates are unavailable. Most, although not all, of the recognized "common" dominants have onset in adult ages while most sex-linked and autosomal recessives have onset at birth or in childhood. Autosomal dominant and X-linked diseases (i.e., the responsible mutant alleles) presumed to be maintained in the population due to a balance between mutation and selection are the ones which may be expected to increase in frequency as a result of radiation exposures. Viewed from this standpoint, the above assumption seems safe only for a small proportion of such diseases; for the remainder, there is no easy way to discriminate between different mechanisms that may be responsible or to rigorously exclude some in favor of some others. Mutations in genes that code for enzymic proteins are more often recessive in contrast to those that code for non-enzymic proteins, which are more often dominant. At the molecular level, with recessives, a wide variety of changes is possible and these include specific types of point mutations, small and large intragenic deletions, multilocus deletions and rearrangements. In the case of dominants, however, the kinds of recoverable point mutations and deletion-type changes are less extensive because of functional constraints. The mutational potential of genes varies, depending on the gene, its size, sequence content and arrangement, location and its normal functions, and can be grouped into three groups: those in which only point mutations have been found to occur, those in which only deletions or other gross changes have been recovered and those in which both kinds of changes are known. Molecular data are available for about 75 Mendelian conditions and these suggest that in approximately 50% of them, the changes categorized to date are point mutations and in the remainder, intragenic deletions or other gross changes; there does not seem to be any fundamental difference between dominants and recessives with respect to the underlying molecular defect.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1994

Two distinct protein isoforms are encoded by ntk, a csk-related tyrosine protein kinase gene.

Recently, we and others have cloned cDNAs encoding a second member of the Csk family of inhibitory tyrosine protein kinases, which we have termed Ntk. Intriguingly, the mouse ntk cDNA sequences published by two independent groups differed by the presence or absence of a 136 nucleotide-insert near their 5' ends. In this report, we demonstrate that this 136 nucleotide-sequence likely corresponds to a complete exon in the ntk gene (termed exon 2), and that the two types of cDNAs/transcripts are produced by alternative splicing. Using ribonuclease protection assays, it was also established that brain and lymphoid organs, as well as most hemopoietic cells, predominantly expressed ntk transcripts lacking exon 2. In contrast, selected hemopoietic cell lines, such as the immature myeloid cell lines 32D cl3(G) and WEHI-3B, exclusively possessed exon 2-bearing RNAs. Interestingly, exon 2 introduced a novel in-frame upstream AUG in the ntk transcript, which is in the appropriate context for translation initiation. Evidence was obtained that this AUG is utilized in vivo, and that it extends the amino-terminal sequence of Ntk by 40 amino acids. Indeed, while exon 2-deficient ntk RNAs were translated into a 52 kilodalton (kDa) polypeptide (p52ntk), those bearing exon 2 produced a 56 kDa protein (p56ntk). Furthermore, p56ntk, but not p52ntk, was recognized by an antiserum directed against the novel amino-terminal sequence encoded by exon 2. Additional biochemical characterizations showed that p52ntk and p56ntk were localized to the cytoplasm, and that they partially accumulated in the detergent-insoluble cellular fraction. This last finding suggested that the Ntk proteins can associate with the cytoskeleton. Finally, through linkage analysis of two multilocus crosses, the ntk gene was mapped to Chromosome 10 in the mouse. Taken together, these data showed that ntk, a csk-related tyrosine protein kinase gene, encodes two protein isoforms expressed in distinct cell types. Moreover, they raised the possibility that Ntk may be involved in the regulation of Src-like enzymes in detergent-insoluble cellular compartments.

3T3 Cells↗

PubMed1995

Mouse tetranectin: cDNA sequence, tissue-specific expression, and chromosomal mapping.

Tetranectin is a plasminogen-binding tetrameric protein originally isolated from plasma. Expression of tetranectin appears ubiquitous, although particularly high expression is noted in the stroma of malignant tumors and during mineralization. To dissect the molecular basis of tetranectin gene regulation, mouse tetranectin cDNA was cloned from a 16-day-old mouse embryo library. Sequence analysis revealed a 992-bp cDNA with an open reading frame of 606 bp, which is identical in length to the human tetranectin cDNA. The deduced amino acid sequence showed high homology to the human cDNA with 76% identity and 87% similarity at the amino acid level. Sequence comparisons between mouse and human tetranectin and some C-type lectins confirmed a complete conservation in the position of six cysteines as well as numerous other amino acid residues, indicating an essential structure for potential function(s) of tetranectin. The sequence analysis revealed a difference in both sequence and size of the noncoding regions between mouse and human cDNAs. Northern analysis of the various tissues from mouse, rat, and cow showed the major transcript(s) to be approximately 1 kb, which is similar in size to that observed in human. Although additional minor bands of 1.5 and 3.3 kb were found in Northern blots, RT-PCR (reverse transcription polymerase chain reaction) analysis failed to provide evidence that these minor bands are products of the tetranectin gene. Finally, the genetic map location for this gene, Tna, was determined to be on distal mouse Chromosome (Chr) 9 by analysis of two sets of multilocus crosses.

Amino Acid Sequence↗

PubMed2003

Typing of nonencapsulated haemophilus strains by repetitive-element sequence-based PCR using intergenic dyad sequences.

Intergenic dyad sequences (IDS) are short repeated elements that have been described for several Haemophilus genomes and for only two other bacterial genera. We developed a repetitive-element sequence-based PCR using an IDS-specific primer as a typing method (IDS-PCR) for nonencapsulated Haemophilus strains and compared this technique with pulsed-field gel electrophoresis (PFGE) of DNA restricted with SmaI. IDS-PCR was rapid, easy to perform, and reproducible, with a high discriminatory capacity for nontypeable Haemophilus influenzae (NTHI) strains. The 69 NTHI strains tested generated 65 different banding patterns. Epidemiologically related strains gave similar or identical fingerprints, and all of the unrelated strains except two showed different patterns. These results were in agreement with those obtained by PFGE. For 20 genital strains usually identified as being biotype IV NTHI and belonging to a cryptic genospecies of Haemophilus with remarkable genetic homogeneity, four bands were significantly present and six bands were significantly absent from the fingerprints. The 20 strains were gathered in 11 closely related profiles, whereas PFGE provided no band when DNA was treated with SmaI. IDS-PCR improved the differentiation previously obtained within this species by ribotyping and multilocus enzyme electrophoresis. Our findings suggest that IDS-PCR is a rapid, reliable, and discriminatory method for typing NTHI strains and is currently the most efficient method for distinguishing strains within the cryptic genospecies of HAEMOPHILUS:

Base Sequence↗

PubMed2001

Multilocus analysis of extracellular putative virulence proteins made by group A Streptococcus: population genetics, human serologic response, and gene transcription.

Species of pathogenic microbes are composed of an array of evolutionarily distinct chromosomal genotypes characterized by diversity in gene content and sequence (allelic variation). The occurrence of substantial genetic diversity has hindered progress in developing a comprehensive understanding of the molecular basis of virulence and new therapeutics such as vaccines. To provide new information that bears on these issues, 11 genes encoding extracellular proteins in the human bacterial pathogen group A Streptococcus identified by analysis of four genomes were studied. Eight of the 11 genes encode proteins with a LPXTG(L) motif that covalently links Gram-positive virulence factors to the bacterial cell surface. Sequence analysis of the 11 genes in 37 geographically and phylogenetically diverse group A Streptococcus strains cultured from patients with different infection types found that recent horizontal gene transfer has contributed substantially to chromosomal diversity. Regions of the inferred proteins likely to interact with the host were identified by molecular population genetic analysis, and Western immunoblot analysis with sera from infected patients confirmed that they were antigenic. Real-time reverse transcriptase-PCR (TaqMan) assays found that transcription of six of the 11 genes was substantially up-regulated in the stationary phase. In addition, transcription of many genes was influenced by the covR and mga trans-acting gene regulatory loci. Multilocus investigation of putative virulence genes by the integrated approach described herein provides an important strategy to aid microbial pathogenesis research and rapidly identify new targets for therapeutics research.

Amino Acid Sequence↗

PubMed1992

Molecular typing of Staphylococcus aureus on the basis of coagulase gene polymorphisms.

Staphylocoagulase, a major phenotypic determinant of Staphylococcus aureus, exists in multiple allelic forms, in part because of the existence of gene variants within the 3'-end coding region. This region contains a series of repeating 81-bp DNA sequences which differ both in the number of tandem repeats and the location of AluI restriction sites among different isolates. Utilizing this finding, we developed a novel typing method for S. aureus based on polymerase chain reaction amplification of the variable region of the coagulase gene followed by AluI restriction enzyme digestion and analysis of restriction fragment length polymorphism (RFLP). Among 30 S. aureus isolates studied initially, a total of 10 distinct RFLP patterns were observed. There was excellent correlation of the RFLP patterns with typing of these isolates by multilocus enzyme electrophoresis at 20 chromosomal loci. This coagulase RFLP method was used to analyze an additional 39 S. aureus isolates and successfully traced the source of an outbreak of methicillin-resistant S. aureus infections at a local hospital.

Bacterial Typing Techniques↗

PubMed1989

Distribution of the P-associated-pilus (pap) region among Escherichia coli from natural sources: evidence for horizontal gene transfer.

Variation in chromosomal DNA in Escherichia coli was studied with probes specific for the P-associated-pilus (pap) region. The presence of DNA homologous to pap was determined by dot blots. Variation in the number of copies of pap and in the organization of internal and flanking sequences was determined by Southern blot hybridization. The 229 strains studied were also classified by O:K:H serotyping and multilocus enzyme electrophoresis. There was considerable heterogeneity in the presence of pap and distribution of pap-homologous DNA in these E. coli strains from natural sources. In general, there was less variation in pap among strains of the same specific O:K:H serotype and enzyme electrophoretic type than among random isolates. There were, however, E. coli strains identified as members of the same clone by O:K:H serotyping and enzyme electrophoresis that were pap positive and pap negative or had different Southern blot patterns for the pap probes (pap type). There were also isolates of the same pap type that differed in two of three O:K:H serotype antigens and the majority of enzymes that determined their enzyme electrophoretic type. These latter two observations were interpreted as evidence for the horizontal (infectious) transfer of the pap-homologous sequences among clones of E. coli.

Bacterial Adhesion↗

PubMed2001

Bacillus sonorensis sp. nov., a close relative of Bacillus licheniformis, isolated from soil in the Sonoran Desert, Arizona.

Eight Bacillus strains isolated from Sonoran Desert soil were shown to belong to a previously unidentified species, for which the name Bacillus sonorensis sp. nov. is proposed. The type strain is strain L87-10T (= NRRL B-23154T). On the basis of phenotypic and genetic data, B. sonorensis is most closely related to Bacillus licheniformis. B. sonorensis can be distinguished from B. licheniformis by salt tolerance, pigmentation, multilocus enzyme electrophoresis, reassociation of genomic DNA and sequence differences in protein-coding genes and 16S rRNA.

Arizona↗

PubMed1999

Genetic diversity in the yeast species Malassezia pachydermatis analysed by multilocus enzyme electrophoresis.

Fifty-two strains of the yeast species Malassezia pachydermatis were analysed by multilocus enzyme electrophoresis. M. pachydermatis appeared to be genetically heterogeneous. A total of 27 electrophoretic types were identified that could be divided into five distinct groups with different host specificities. The diversity revealed by this electrophoretic method matched remarkably well the reported genetic variability obtained by comparing large subunit rRNA sequences. This study also suggests that genetic exchanges can occur in the anamorphic species M. pachydermatis.

Animals↗

PubMed1998

Sequence polymorphism in the beta-tubulin gene reveals heterogeneous and variable population structures in Cryptosporidium parvum.

Restriction fragment length polymorphism (RFLP) analysis of isolates of Cryptosporidium parvum has revealed two subgroups, termed H and C. The limited resolution of the RFLP method precludes an in-depth study of the genetic structure of C. parvum populations. Published C. parvum restriction polymorphisms lie within protein-coding regions known to be more homogeneous than noncoding sequences. To better assess the degrees of heterogeneity between and within C. parvum isolates, sequence polymorphism in the beta-tubulin intron, the only C. parvum intron described to date, was investigated. In contrast to the two genotypes distinguished by multilocus RFLP, several alleles were detected by sequence and RFLP analysis of the beta-tubulin intron and adjacent exon 2. Isolates carrying different beta-tubulin alleles were found. Significantly, one of the beta-tubulin alleles present in two geographically unrelated isolates combined features of C- and H-type isolates, suggesting that it might have arisen from a recombination event. A comparison of multiple samples of a calf-propagated laboratory isolate showed that the ratio of different beta-tubulin alleles fluctuated during serial passage.

Animals↗

PubMed1992

Evidence consistent with horizontal transfer of the gene (emm12) encoding serotype M12 protein between group A and group G pathogenic streptococci.

Human isolates of Lancefield group G streptococci harbor sequences homologous with the structural gene (emm) encoding M protein, a major virulence factor in Streptococcus pyogenes (a group A Streptococcus species). We used DNA-DNA hybridization, restriction endonuclease chromosomal profiling, and multilocus enzyme electrophoresis to examine genetic relationships between group A and group G streptococcal strains expressing homologous serologic type 12 M (M12) protein. All M12 group A strains studied had very similar restriction endonuclease genomic profiles and multilocus enzyme genotypes. In contrast, the restriction enzyme genomic profile and multilocus enzyme genotype of the M12 group G strain CS140 were strikingly different from those characterizing the M12 group A organisms. DNA-DNA hybridization studies revealed, on average, 57% genomic similarity between the M12 group A and group G strains. Taken together, our data demonstrate that a gene encoding M12 protein occurs in two highly divergent chromosomal backgrounds, a result suggesting that an episode of horizontal gene transfer and recombination has occurred between two streptococcal lineages.

Antigens, Bacterial↗