JP2013081467A - Quick detection of highly-pathogenic st-17 clone of b streptococcus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide polynucleotides enabling quick, simple and specific detection of B Streptococcus highly-pathogenic ST-17 clones, polypeptides encoded by the polynucleotides, antibodies against the polypeptides, and kits and methods for the specific detection using the polynucleotides, the polypeptides, or the antibodies.SOLUTION: There is provided a group B Streptococcus gene encoding a Gbs2018 surface protein of a strain of the ST-17 clone which consists of a specific sequence.

Description

[Field of the Invention]
The present invention relates to a polynucleotide that enables rapid, simple and specific detection of highly pathogenic ST-17 clones of B Streptococcus.

  The present invention also relates to an antibody against the polypeptide, similarly to the polypeptide encoded by the polynucleotide.

  The present invention also relates to kits and methods for specifically detecting B STREPTOCOCCUS highly pathogenic ST-17 clones using the polynucleotides, polypeptides or antibodies of the present invention.

[Background / Prior art]
Streptococcus agalactiae (also known as Group B Streptococcus (GBS)) is a capsulated gram-positive bacterium that can be found in the gastrointestinal and genitourinary tracts of 40% of healthy adults bacterium). This commensal organism can be considered a major cause of morbidity and mortality in neonates in developed countries (Schrag et al., 2002).

  The most predictive factor of neonatal infection with GBS relates to the transmission of S. agalactiae from mother to newborn. This contamination generally occurs across the reproductive organs through inhalation and ingestion of contaminated amniotic liquid. It is estimated that at least 50% of newborns exposed to GBS colonize and 2% develop infection (Schuchat, 1999). Invasive GBS infections in neonates frequently die in pneumonia and bacteremia (approximately 80% cases), less frequently in meningitis (10%), and in rare cases (4%) (Schuchat, 1999). GBS-induced meningitis leads to significant morbidity and severe neurological damage.

  About 80% of GBS neonatal infections occur within the first week and are referred to as early-onset diseases (EOD). Most cases of EOD are clinically apparent on the day of birth or within the first 72 hours. Late-onset diseases (LODs) usually occur in infants between 1 week and 3 months of age.

  To date, nine capsule serotypes GBS have been described (Ia, Ib, and II to VIII). Of these, the serotype III GBS strain is particularly important. This is because they are responsible for the majority of invasive neonatal infections in North America and Europe and almost all neonatal meningitis.

  Research has also shown that only a limited number of strains of serotype III ("highly-virulent clones") have been found in the vast majority of neonatal invasive diseases, and almost all It was suggested that it may cause meningitis cases. Recently, molecular epidemiological studies have demonstrated that: Most GBS strains responsible for invasive neonatal infection belong to a homogeneous serotype III clone called ST-17. Yes (Jones et al, 2003; Luan et al, 2005).

  Among the strategies set up to reduce neonatal infections caused by GBS, the United States and other Western worlds by performing selective antimicrobial prevention based on screening strategies or risk analysis Although the incidence of EOD was reduced, the incidence of LOD was not reduced (Schrag, 2004). Progress has been made in preventing EOD and LOD currently represents a growing proportion of all GBS neonatal infections (Schrag, 2004). In addition, implementation of preventive guidelines has increased the use of antibiotics, resulting in the emergence of antimicrobial resistance in both GBS and other birth pathogens.

  An alternative strategy would be to identify highly pathogenic GBS early to target and set up antibacterial prophylaxis.

  Current recommendations for preventing group B streptococcal disease are screened for GBS colonization in pregnant women during the 34-38 week gestation period and for antibioprophylaxis during labor To identify candidates. However, the culture method remains a “gold standard” technique for detecting the presence of GBS in vaginal secretions. Although the culture method allows efficient identification of GBS members, it has failed to distinguish potentially highly pathogenic clones from others.

  Recent epidemiological molecular techniques have proven to be powerful techniques for analyzing phylogeny in GBS isolates belonging to the same serotype. Among these techniques, multilocus sequencing typing (MLST), multilocus enzyme electrophoresis (MLEE), pulsed field gel electrophoresis (PFGE), restriction digest pattern ) And restriction fragment length polymorphism (RFLP) are techniques that are particularly used.

  However, these techniques are fastidious and time consuming and cannot be routinely used in obstetric medicine for testing for the presence of pathogenic ST-17 strains during pregnancy or at the time of delivery .

  Thus, genes that are specific for highly pathogenic GBS strains are not only the limits of antibiotic use, but are also key in tracking newborns that colonize these highly pathogenic strains. It will have clinical significance.

  The problem of the present invention is to identify ST-17-specific alleles of the gene gbs2018 to enable rapid and efficient detection of infection by highly pathogenic serotype III GBS strains.

  In particular, the present invention relates to a polynucleotide comprising the gene or a fragment thereof.

  The invention also relates to a polypeptide encoded by a polynucleotide as defined herein.

  The present invention also relates to polyclonal and monoclonal antibodies against the polypeptides encoded by the polynucleotides defined herein.

  Furthermore, the present invention includes a method for detecting the presence of the ST-17 strain in a biological sample.

  Another aspect of the present invention relates to a kit for detecting GBS ST-17 strain from a biological sample.

FIG. 1 shows the nucleic acid sequence and corresponding amino acid sequence of the gbs2018 gene of ST-17 strain NEM318. The first line points to nucleotide sequences grouped by codon; the second line points to the amino acid sequence corresponding to the codon in the three letter code. Translation of the first codon is shown in bold (same for stop codon). The nucleic acid number is indicated at the right end of the first line, while the amino acid number is indicated below the amino acid residue (third line). The nucleic acid sequence (SEQ ID NO: 1) of the coding sequence of the gbs2018-NEM318 gene contains 1569 nucleotides and encodes a polypeptide sequence (SEQ ID NO: 2) of 522 amino acids. FIG. 1 shows the nucleic acid sequence and corresponding amino acid sequence of the gbs2018 gene of ST-17 strain NEM318. The first line points to nucleotide sequences grouped by codon; the second line points to the amino acid sequence corresponding to the codon in the three letter code. Translation of the first codon is shown in bold (same for stop codon). The nucleic acid number is indicated at the right end of the first line, while the amino acid number is indicated below the amino acid residue (third line). The nucleic acid sequence (SEQ ID NO: 1) of the coding sequence of the gbs2018-NEM318 gene contains 1569 nucleotides and encodes a polypeptide sequence (SEQ ID NO: 2) of 522 amino acids. FIG. 2 shows the nucleic acid sequences and corresponding amino acid sequences of segments S1 (FIG. 2a), S6 (FIG. 2b) and S7 (FIG. 2c) of the gbs2018 gene of ST-17 strain. The first line points to nucleotide sequences grouped by codon; the second line points to the amino acid sequence corresponding to the codon in the three letter code. The nucleic acid number is indicated at the right end of the first line, while the amino acid number is indicated below the amino acid residue (third line). The nucleic acid sequence of segment S1 (SEQ ID NO: 3) contains 99 nucleotides and encodes a polypeptide sequence of 33 amino acids (SEQ ID NO: 4). The nucleic acid sequence of segment S6 (SEQ ID NO: 7) contains 291 nucleotides and encodes a 97 amino acid (SEQ ID NO: 8) polypeptide sequence. The nucleic acid sequence of segment S7 (SEQ ID NO: 9) contains 180 nucleotides and encodes a polypeptide sequence of 60 amino acids (SEQ ID NO: 10). FIG. 3 shows the nucleic acid sequences and corresponding amino acid sequences of segments S8 (FIG. 3a) and S10 (FIG. 3b) of the gbs2018 gene of ST-17 strain. The first line points to nucleotide sequences grouped by codon; the second line points to the amino acid sequence corresponding to the codon in the three letter code. The nucleic acid number is indicated at the right end of the first line, while the amino acid number is indicated below the amino acid residue (third line). The nucleic acid sequence of segment S8 (SEQ ID NO: 11) contains 192 nucleotides and encodes a polypeptide sequence of 63 amino acids (SEQ ID NO: 12). The nucleic acid sequence of segment S10 (SEQ ID NO: 5) contains 570 nucleotides and encodes a 190 amino acid polypeptide sequence (SEQ ID NO: 6). FIG. 4 shows the nucleic acid sequence and corresponding amino acid sequence of S11a (FIG. 4a) and S11b (FIG. 4b) of the gbs2018 gene of the ST-17 strain. The first line points to nucleotide sequences grouped by codon; the second line points to the amino acid sequence corresponding to the codon in the three letter code. The nucleic acid number is indicated at the right end of the first line, while the amino acid number is indicated below the amino acid residue (third line). The nucleic acid sequence of segment S11a (SEQ ID NO: 13) contains 216 nucleotides and encodes a polypeptide sequence of 72 amino acids (SEQ ID NO: 14). The nucleic acid sequence of segment S11b (of SEQ ID NO: 15) contains 237 nucleotides and encodes a polypeptide sequence of 79 amino acids (SEQ ID NO: 16). FIG. 5 corresponds to the nucleic acid sequences of amplification products obtained with different primer sets of the present invention. The nucleic acid sequence of ST-17S / ST-17AS (208 nucleotides) (SEQ ID NO: 35) corresponds to the amplification product obtained with primer ST-17S of SEQ ID NO: 33 and ST-17AS of SEQ ID NO: 34 (Figure 5a) . The nucleic acid sequence of O13 / ST-17AS (101 nucleotides) (SEQ ID NO: 36) corresponds to the amplification product obtained with primer O13 of SEQ ID NO: 29 and ST-17AS of SEQ ID NO: 34 (Figure 5b). The nucleic acid sequence of O13 / O12 (107 nucleotides) (SEQ ID NO: 37) corresponds to the amplification product obtained with primer O13 of SEQ ID NO: 29 and O12 of SEQ ID NO: 28 (Figure 5c). The nucleic acid sequence of ST-17S / O12 (214 nucleotides) (SEQ ID NO: 38) corresponds to the amplification product obtained with primer ST-17S of SEQ ID NO: 33 and O12 of SEQ ID NO: 28 (Figure 5d). The nucleic acid sequence of O11 / ST-17AS (543 nucleotides) (SEQ ID NO: 39) corresponds to the amplification product obtained with primer O11 of SEQ ID NO: 27 and ST-17AS of SEQ ID NO: 34 (Figure 5e). The nucleic acid sequence of O11 / O12 (549 nucleotides) (SEQ ID NO: 40) corresponds to the amplification product obtained with primer O11 of SEQ ID NO: 27 and O12 of SEQ ID NO: 28 (Figure 5f). FIG. 6 is a phylogenetic tree of genes encoding different chimeric forms of the Gbs2018 surface protein in 31 GBS isolates belonging to different sequence types (ST). The alignment and comparison of the DNA sequences of GBS isolates reveals a three-ways lineage and classifies the gbs2018 allele types of the three clusters (A, B and C). The percentage of sequence branching is indicated below the phylogenetic tree. FIG. 7 represents the mosaic structure of the gene encoding the three allelic forms of the surface protein Gbs2018. Representative members of each phylogenetic cluster (A, B, and C; defined in FIG. 5) are presented. FIG. 8 represents the specific detection of ST-17 among GBS isolates. The GBS strain was identified by PCR amplification using the primer pair dltRS / dltRAS (specific to dltR, a 234-pb amplicon). ST-17S / ST-17AS (specific to gbs2018-ST-17, 210-bp amplicon) was used to identify the ST-17 strain. In panel A, the 10 samples tested were ST-17 clone complexes: 1, BM110; 2, COH1; 3, NEM318; 4, CCH56; 5, CCH63; 6, CCH80; 7, CCH76; 8, CCH77; 9, CCH81; 10, serotype III GBS strain belonging to CCH82. In panel B, the 10 GBS strains tested are of different serotypes and are diverse ST: 1, NEM316 (serotype III, ST-23); 2, GBS 2603V / R (serotype V, ST- 19 *); 3, CCH178 (serotype V, ST-1); 4, CCH75 (serotype III, ST-2); NEM1573 (serotype Ia, ST-6); CCH53 (serotype Ib, ST-8) ); NEM1010 (serotype II, ST-9); CCH179 (serotype II, ST-10); CCH180 (serotype I, ST-23); CCH72 (serotype III, ST-41). Molecular weight marker 1 kb ladder-plus (Gibco-BRL) was added to lane M.

[Detailed description]
The present invention relates to a polynucleotide selected from the following group:
a) a Group B streptococcal gene encoding the surface protein Gbs2018 of the strain of the ST-17 clone, comprising a nucleic acid sequence having the sequence S10 of SEQ ID NO: 5 (Figure 3b), and at least one A gene comprising a domain consisting of at least one nucleic acid sequence having the sequence S11a of SEQ ID NO: 13 (FIG. 4a) and / or the sequence S11b of SEQ ID NO: 15 (FIG. 4b);
b) a polynucleotide that hybridizes with the gene of a) under stringent conditions;
c) a fragment derived from a group B streptococcal gene defined in a) or a corresponding fragment derived from a polynucleotide that hybridizes with the gene defined in a) under stringent conditions, A fragment encoding a polypeptide that is suitable for use in a method for the specific detection of GBS strains of -17 clones or comprises an epitope of said surface protein Gbs2018;
d) a polynucleotide substantially complementary to a fragment of the gene defined in a) or of the polynucleotide defined in b) or of the fragment defined in c), which is specific for the GBS strain of the ST-17 clone A polynucleotide encoding a polypeptide suitable for use in a method for complete detection or comprising an epitope of said surface protein Gbs2018;
e) However, the polynucleotide is not a gene having a coding sequence called gbs2018-NEM318 (FIG. 1) of SEQ ID NO: 1.

Specific polynucleotides of the present invention are those selected from the following group:
a) a group B streptococcal gene encoding the surface protein Gbs2018 of the strain of the ST-17 clone, comprising a nucleic acid sequence having the sequence S10 of SEQ ID NO: 5 (Figure 3b), and at least two Consisting of at least one nucleic acid sequence comprising one copy of the nucleic acid sequence S11a (Fig. 4a) or SEQ ID No. 15 of the nucleic acid sequence S11b (Fig. 4b) or at least one copy of each of the nucleic acid sequences S11a and S11b A gene comprising a domain;
b) A polynucleotide that hybridizes with the gene of a) under stringent conditions (including those that hybridize with two identical or different segments selected from the group of S10 segment and S11a segment and S11b segment) Is);
c) A fragment derived from the group B Streptococcus gene defined in a) or a fragment derived from a polynucleotide that hybridizes with the gene under stringent conditions, and is specific to the GBS strain of ST-17 clone A fragment encoding a polypeptide suitable for use in a method for detection or comprising an epitope of said surface protein Gbs2018;
d) a polynucleotide substantially complementary to a fragment of the gene defined in a) or of the polynucleotide defined in b) or of the fragment defined in c), which is specific for the GBS strain of the ST-17 clone A polynucleotide encoding a polypeptide which is suitable for use in a method for simple detection or which contains an epitope of said surface protein Gbs2018.

  In certain embodiments, the defined fragments of the invention are suitable for use in a method for detection (particularly suitable for the specific detection of GBS strains of ST-17 clones).

  As used herein, the expression “substantially complementary” means that the considered polynucleotide is completely complementary to the reference polynucleotide or has different characters at several positions. (Still being substantially the same length) means to hybridize with the reference polynucleotide under stringent conditions.

  “Polynucleotide” as used herein refers to a nucleic acid that differs from the genome of S. agalactiae. In a particular embodiment, such a polynucleotide is derived from the genome of S. agalactiae, in particular a gene or fragment of a gene of S. agalactiae. In that case, the polynucleotide is isolated or purified (ie, separated from its natural environment in the genome). The polynucleotides of the present invention, said to be derived from the genome of S. agalatiae, comprise or in particular reflect genetic information contained in the corresponding sequence in the genome.

  The polynucleotide of the present invention has a sequence having an exact counterpart in the genome of S. agalactiae from which it is derived or substantially corresponding, the nucleotide composition of which is related to said sequence in the genome. It is meant that the modifications within can vary to the extent that does not substantially affect the nature of the resulting polynucleotide that hybridizes with the genomic sequence from which it is derived under stringent conditions.

  Therefore, a polynucleotide derived from the gbs2018 gene can have several nucleotide substitutions, additions or deletions of the original gene.

  The polynucleotides of the present invention can be prepared by any available method, including extraction from the genome, involving the use of restriction enzymes and / or synthesis, etc., chemical synthesis and / or recombination. Technology is included.

  Any ex vivo production method, etc. (as well as combinations thereof) is suitable for such preparation. In certain embodiments, these methods may include nucleic acid extraction from its natural environment, such as hydrolysis with restriction enzymes, amplification and / or synthesis (especially chemical synthesis) of the desired polynucleotide. Good.

  The term “polynucleotide” is used interchangeably with “nucleic acid” and “oligonucleotide”. The term includes, but is not limited to, DNA, RNA, combinations of DNA and RNA sequences greater than two nucleotides. The polynucleotide of the present invention is double stranded or single stranded.

  By “gene” is meant a nucleic acid molecule whose nucleotide sequence comprises or consists of a sequence encoding a polypeptide, ie, a nucleic acid molecule that comprises or consists of an ORF (open reading frame). Thus, a gene according to the present invention includes a nucleic acid molecule that does not have a promoter or control sequence usually located upstream or downstream of the coding sequence. In such cases, the gene is a molecule limited to the coding sequence. The expression “gene” also encompasses molecules having both coding sequences for polypeptides and control sequences, including promoter and / or terminator sequences. The control sequence may be a native sequence present in the reference genome of S. agalactiae or a heterologous sequence (ie, a sequence not naturally associated with a coding sequence in the genome).

  In a particular embodiment, the term “gene” refers to the gbs2018 gene of group B streptococcus of the ST-17 clone. In particular, the gbs2018 gene can be described by the polynucleotide gbs21018-NEM318 (Figure 1) of SEQ ID NO: 1.

  As used herein, `` ST-17 clone '' refers to a bacterial strain belonging to the Streptococcus agalactiae strain (also known as Group B Streptococcus (GBS)), more specifically `` Type III '' It means a bacterial strain belonging to the GBS serotype, in particular a strain of highly pathogenic strain [Jones N et al., 2003; Luan SL et al., 2005]. Sequence type identification and characteristics include, for example, multidentate enzyme electrophoresis (MLEE), pulsed field gel electrophoresis (PFGE), restriction digestion pattern and restriction fragment length polymorphism (RFLP), as well as combinations thereof Means known methods including, but not limited to, culture methods or molecular methods. The inventor has performed genetic studies in various sequence types of GBS strains, including three clusters (ie, clusters A, B and C, where cluster C represents and contains only strains of sequence type 17 ) Was created. ST-17 is notably the following strains CCH56, CCH63, CCH76, CCH71, CCH77, CCH60, CCH80, CCH81, CCH69, CCH73, CCH82, BM110 [Musser JM et al., 1989; Stalhammar-Carlemalm M, 1993], NEM623 , COH1 [Wessels MR and al., 1989] and NEM318 [Gaillot et al., 1997].

  One specific example of the ST-17 strain is Collection Nationale de Cultures de Microorganismes (CNCM), INSTITUT PASTEUR, 25 rue du Docteur Roux, F-75724 PARIS CEDEX 15, with accession number CNCM I-3537 on December 2, 2005. Streptococcus agalactiae NEM318 deposited at NEM318 is a serotype III, tetracycline resistant strain of the ST-17 type clone [Gaillot et al., 1997]. NEM318 is grown in liquid culture or agar plates shaken with Todd Hewitt medium at 37 ° C.

  As used herein, the term “segment S10” or “S10” refers to a polynucleotide or segment that is specific for the allelic form of gene gbs2018 of the GBS strain of sequence type 17 (ie, ST- Not found in serotype III strains that are not 17). The “segment S10” or “S10” can be defined as an internal region of the gbs2018 gene following the N-terminal sequence of the gbs2018 gene, and is shared by the GBS strains. A particular polynucleotide corresponding to the S10 segment has, for example, 570 nucleotides and has the nucleotide sequence S10 of SEQ ID NO: 5 (Figure 3b) [this is the sequence gbs2018-NEM318 (CNCM I-3537 and Figure 1 of SEQ ID NO: 1. 1) contained between nucleotide positions 100 and 669 in the ST-17 allelic sequence of the gbs2018 gene].

  As used herein, the term “segment S11” or “S11” refers to a polynucleotide (or segment) that is a specific type of allelic variant of the gene gbs2018 of the GBS strain of sequence type 17 (ie, the ST-17 strain) Not found in available strains of serotype III). The “segment S11” or “S11” can be defined as an internal region of the gbs2018 gene. Depending on the ST-17 strain, the ST-17 allelic form of gene gbs2018 can contain one or two copies of the S11 segment. By copy is meant two S11 sequences that are identical or different but homologous. Specific homologous polynucleotides for the S11 segment are, for example, the sequence S11a of SEQ ID NO: 13 (Figure 4a) and the sequence S11b of SEQ ID NO: 15 (Figure 4b).

  In one embodiment, the present invention provides for a strain of an ST-17 clone comprising one copy of sequence S11a (Figure 4a) and one copy of sequence S11b (Figure 4b) of SEQ ID NO: 13. The polynucleotide relates to the gbs2018 gene. In particular, the gbs2018 gene of the present invention comprises a domain having contiguous S11a and S11b segments.

  The present invention also relates to a polynucleotide which is a gbs2018 gene of a strain of ST-17 clone containing two copies of S11a segment or two copies of S11b segment (adjacent or not in the gene). About.

  The present invention also relates to the use of a polynucleotide that is the gbs2018 gene of a strain of ST-17 clone in which only one copy of the S11 segment is present.

  However, in certain embodiments, the present invention does not encompass a particular gene having the sequence disclosed for the COH-1 strain in Tettelin H et al, 2005 corresponding to the sequence gbs2018-NEM318 of SEQ ID NO: 1 . Nevertheless, the present invention includes the use of fragments of the genes defined in this application, the genes defined in this application and fragments thereof.

  The present inventor has shown that the S10 and S11 segments in the gbs2018 gene are the determinants of the ST-17 strain in the GBS strain classification (see FIG. 6). reference). In addition, the inventor has indicated the following matters: the matters are the presence of S10 and / or one or more (especially two) copies of the S11 segment (S11a or S11b disclosed herein) Or a combination thereof) on the one hand strain BM110 (having two copies of the S11 segment for said strain) and on the other hand strain COH-1 or strain NEM318 (for said strain, one copy of one S11 segment) The distinction between the two sublines of the ST-17 strain represented by

  In certain embodiments of the invention, the polynucleotide has been disclosed in relation to the ability to hybridize with the gbs2018 gene disclosed herein or a fragment thereof as defined in the application.

  In a particular embodiment, the gbs2018 gene (for which the ability to hybridize is determined) is one strand of the gene of strain NEM318 deposited with the CNCM under number I-3537.

  In a particular embodiment, the fragment whose hybridization capacity is determined is the S10 fragment or S11 fragment of the gene of strain NEM318 deposited at CNCM under number I-3537 or a complementary fragment thereof.

  In certain embodiments, the fragment derived from the gbs2018 gene as defined in this application is defined as suitable for use in a method for detection, particularly for the specific detection of GBS strains of ST-17 clones. Is done.

  According to this embodiment, the strain itself is not necessarily detected, but the method allows in vitro detection of infection by such strain (in particular, its DNA or its polypeptide product or direct antibody against said product). Or by indirect detection).

  As used herein, “stringent conditions” are described, for example, by Sambrook et al. (Sambrook et Russel. 2001. Molecular cloning: a laboratory manual, 3rd ed., Cold Spring Harbor Laboratory Press, Cold Means hybridization conditions within the knowledge of a person skilled in the art as defined in Spring Harbor, NY). Regarding the description of such conditions suitable for the practice of the present invention, “stringent conditions” are consistent with conditions that allow specific hybridization of two single-stranded DNA molecules after one “washing step”. To do. For example, the hybridization can be performed using SSC 6X, SDS 0.5%, Denhardt's solution 5X and a solution containing 100 μg of nonspecific DNA, or any other solution of any equivalent ionic strength. Or about 35-65 ° C. A “washing step” that includes at least one wash is, for example, about 65 in solutions containing at max 0.2X SSC and up to 0.1% SDS or any other solution of any equivalent ionic strength. Can be performed at ° C. However, one skilled in the art can vary the appropriate conditions to take into account varying factors such as, for example, the length of the polynucleotide sequence, the base composition, the type of ions present.

  Use of suitable fragments in the method for detection (especially for specific detection of ST-17 strains) includes, for example, fragments that are targets for detection, or primers for extension or amplification, or detection A probe for amplification or extension of the targeted gene sequence, as well as a fragment encoding a polypeptide of at least 6 amino acids (the polypeptide is recognized by the antibody according to the invention) Can be involved.

  The expression “suitable for” means that the fragment is selected and derived from a specific region of the gene gbs2018 of the GBS strain that characterizes the S. agalactiae sequence type 17 strain or the gene or fragment thereof It means to a polynucleotide selected and derived from a polynucleotide that hybridizes under stringent conditions or a polynucleotide complementary to the gene or fragment thereof. In certain embodiments, the region is not found in other strains such as serotype III strains that are not ST-17 strains or strains described in Table S2 below. Thus, polynucleotides suitable for methods for detecting ST-17 strains (especially fragments of the gbs2018 gene) can be found between ST-17 strains and other GBS strains of serotype III in a specific manner of detection. It enables identification. Such polynucleotides provide a tool for designing detection methods that have sensitivity and specificity consistent with the need for diagnosis or determination of infection with ST-17 strains. In certain embodiments, such appropriate polynucleotides allow exclusive detection of ST-17 clones.

  In one embodiment, the expression “suitable for” includes the entire or part of the nucleic acid sequence of segment S10 of SEQ ID NO: 5 (FIG. 3b), or the segment S11a (FIG. 4a) and / or the sequence of SEQ ID NO: 13. The whole or part of the nucleic acid sequence of segment S11b (Figure 4b), number 15 or a fragment that contains a sequence that is complementary to these sequences or that hybridizes under stringent conditions to any of these sequences. Related.

  In a particular embodiment, the expression “suitable for” is obtained from the nucleic acid sequence of oligonucleotide ST-17S of SEQ ID NO: 33 (Table S1) obtained with a primer set consisting of ST-17S and ST-17AS. Whole or part, whole or part of the nucleic acid sequence of oligonucleotide ST-17AS (Table S1) of SEQ ID NO: 34, or whole nucleic acid sequence of the amplification product ST-17S / ST-17AS (Figure 5a) of SEQ ID NO: 35 Or a portion, or a fragment that contains a sequence that is complementary to these sequences or any sequence that hybridizes under stringent conditions to any of these sequences.

  In another specific embodiment, the expression “suitable for” includes all or part of the nucleic acid sequence of oligonucleotide O11 of SEQ ID NO: 27 (Table S1), oligonucleotide O12 of SEQ ID NO: 28 (Table S1) Or a fragment containing all or part of the nucleic acid sequence of the oligonucleotide O13 of SEQ ID NO: 29 (Table S1).

  In a further specific embodiment, the expression “suitable for” is the nucleic acid sequence of the amplification product O13 / ST-17AS (FIG. 5b) obtained in the primer set consisting of O13 and ST17-AS, SEQ ID NO: 36. Or fragments that contain sequences that are complementary to these sequences or that hybridize under stringent conditions to any of these sequences.

  In another embodiment, the expression “suitable for” is the whole or part of the nucleic acid sequence of the amplification product O13 / O12 (FIG. 5c) of SEQ ID NO: 37 obtained with a primer set consisting of O13 and O12. Or a fragment containing a sequence that is complementary to these sequences or that hybridizes under stringent conditions to any of these sequences.

  In a further embodiment, the expression “suitable for” comprises the entire nucleic acid sequence of the amplification product ST-17S / O12 (FIG. 5d) of SEQ ID NO: 38 obtained with a primer set consisting of ST-17S and O12. Or a portion, or a fragment that contains a sequence that is complementary to these sequences or any sequence that hybridizes under stringent conditions to any of these sequences.

  In another specific embodiment, the expression “suitable for” is the nucleic acid of the amplification product O11 / ST-17AS (FIG. 5e) of SEQ ID NO 39 obtained with a primer set consisting of O11 and ST17-AS. It relates to whole or part of the sequence, or a fragment containing a sequence complementary to these sequences or any sequence that hybridizes under stringent conditions with any of these sequences.

  In a further embodiment, the expression “suitable for” comprises all or part of the nucleic acid sequence of the amplification product O11 / O12 (FIG. 5f) of SEQ ID NO: 40 obtained with a primer set consisting of O11 and O12. Or a fragment that contains a sequence that is complementary to these sequences or that hybridizes under stringent conditions to any of these sequences.

  The term “specific” as used herein relates to the ability to detect sequence type 17 GBS strains using the means detailed in the present invention. According to another particular embodiment of the present invention, the specific detection of ST-17 GBS strain in a biological sample allows the strain to be extracted from other microorganisms including bacteria, viruses or parasites. It becomes possible to identify. In a further specific embodiment, the GB-17 strain of ST-17 is detected, but no other Streptococcus strain is detected. Preferably, the detection excludes that other GBS strains are detected in the sample.

  A specific polynucleotide suitable for practicing the present invention is the gbs2018 gene of sequence gbs2018-NEM318 (FIG. 1) having SEQ ID NO: 1 or a fragment thereof as defined above (particularly the ST-17 clone) Is a suitable fragment for use in methods for detection such as specific detection of GBS strains).

  Another polynucleotide of the present invention is a fragment derived from the S10 segment in the gbs2018 gene of the ST-17 clonal strain.

  In a particular embodiment, said polynucleotide is a fragment derived from the S10 segment having the sequence S10 of SEQ ID NO: 5 (Figure 3b). In particular, this fragment is selected in such a way that it is suitable for use in a method for detection (especially suitable for the specific detection of GBS strains of ST-17 clones).

  Certain polynucleotides of the present invention are derived from the genes defined in this application and are at least 10, especially 10-30, especially at least 15, such as 15-30, especially at least 20, such as 20-30, or 20 A DNA fragment having ˜25 nucleotides. Specific sizes within the ranges defined above are encompassed within any range constructed from the framework or drawings of the present invention.

  Another specific polynucleotide of the invention is derived from said gene and is 10 to 700, especially at least 50, such as 50 to 700 or at least 100, especially 100 to 500, especially at least 200, such as 200 to 500, or It is a DNA fragment having 200 to 300 nucleotides. Specific sizes within the ranges defined above are encompassed within any range constructed from the frame or drawing of the present invention. Such polynucleotides are in particular amplification products obtained with the oligonucleotides disclosed in the present invention (used as amplification primers).

The invention particularly relates to fragments selected from the following sequences:
a) a polynucleotide having SEQ ID NO: 33;
b) a polynucleotide having SEQ ID NO: 34;
c) a polynucleotide having SEQ ID NO: 27;
d) a polynucleotide having SEQ ID NO: 28;
e) a polynucleotide having SEQ ID NO: 29;
f) a polynucleotide (particularly a polynucleotide comprising SEQ ID NO: 35) which is an amplification product obtained when the DNA of GBS strain is amplified with a primer set comprising SEQ ID NO: 33 and SEQ ID NO: 34;
g) a polynucleotide that is an amplification product obtained by amplifying the DNA of GBS strain with a primer set consisting of SEQ ID NO: 29 and SEQ ID NO: 34 (particularly a polynucleotide consisting of SEQ ID NO: 36);
h) A polynucleotide (in particular, a polynucleotide comprising SEQ ID NO: 37) which is an amplification product obtained when the DNA of GBS strain is amplified with a primer set comprising SEQ ID NO: 29 and SEQ ID NO: 28;
i) A polynucleotide (in particular, a polynucleotide comprising SEQ ID NO: 38) which is an amplification product obtained when the DNA of GBS strain is amplified with a primer set comprising SEQ ID NO: 33 and SEQ ID NO: 28;
j) a polynucleotide that is an amplification product obtained by amplifying the GBS strain DNA with a primer set comprising SEQ ID NO: 27 and SEQ ID NO: 34 (particularly a polynucleotide comprising SEQ ID NO: 39);
k) a polynucleotide which is an amplification product obtained by amplifying the GBS strain DNA with a primer set comprising SEQ ID NO: 27 and SEQ ID NO: 28 (particularly a polynucleotide comprising SEQ ID NO: 40);
l) a polynucleotide that is substantially complementary to one strand of one of polynucleotides a) to k);
m) a polynucleotide that hybridizes with the polynucleotide of l) under stringent conditions;
n) a polynucleotide suitable for targeting the gbs2018 gene of a ST-17 clone or a fragment thereof, the sequence comprising the S10 and / or S11 segment of the gene or the S10 and / or S11 segment of the gene A polynucleotide for amplifying and / or detecting a sequence comprising:

  A particular polynucleotide fragment of the present invention is derived from a segment designated S11 in the gbs2018 gene of the ST-17 clonal strain.

  In a particular aspect of the invention, the S11 region is SEQ ID NO: 13 sequence S11a (FIG. 4a) and / or SEQ ID NO: 15 sequence S11b (FIG. 4b).

The present invention also relates to a primer set suitable for use in a method for detecting DNA of GBS strain of ST-17 clone or for detecting a product derived from such DNA. For primer sets comprising or consisting of the following primer pairs:
a) ST-17S having the sequence of SEQ ID NO: 33 and ST-17AS having the sequence of SEQ ID NO: 34;
b) ST-17S having the sequence of SEQ ID NO: 33 and O12 having the sequence of SEQ ID NO: 28;
c) O11 having the sequence of SEQ ID NO: 27 and O12 having the sequence of SEQ ID NO: 28;
d) O12 having the sequence of SEQ ID NO: 28 and O13 having the sequence of SEQ ID NO: 29;
e) O11 having the sequence of SEQ ID NO: 27 and ST-17AS having the sequence of SEQ ID NO: 34;
f) O13 having the sequence of SEQ ID NO: 29 and ST-17AS having the sequence of SEQ ID NO: 34;
g) a primer pair substantially complementary to the primers in a) to f);
h) a primer pair suitable for targeting the gbs2018 gene or fragment thereof of each ST-17 clone, wherein each polynucleotide comprises a sequence comprising the S10 and / or S11 segment of the gene or S10 and Primer pair for amplifying sequences consisting of S11 segments.

  In a particular embodiment, the primer pair consists of ST-17S having the sequence of SEQ ID NO: 33 and ST-17AS having the sequence of SEQ ID NO: 34.

  In a further embodiment, the primer pair consists of ST-17S having the sequence of SEQ ID NO: 33 and O12 having the sequence of SEQ ID NO: 28.

  In a further embodiment, the primer pair consists of O11 having the sequence of SEQ ID NO: 27 and O12 having the sequence of SEQ ID NO: 28.

  In a further embodiment, the primer pair consists of O12 having the sequence of SEQ ID NO: 28 and O13 having the sequence of SEQ ID NO: 29.

  In a further embodiment, the primer pair consists of O11 having the sequence of SEQ ID NO: 27 and ST-17AS having the sequence of SEQ ID NO: 34.

  In a further embodiment, the primer pair consists of O13 having the sequence of SEQ ID NO: 29 and ST-17AS having the sequence of SEQ ID NO: 34.

  In a further embodiment, the primer pair consists of O13 having the sequence of SEQ ID NO: 27 and O8 having the sequence of SEQ ID NO: 24.

  The term “primers” refers to short polynucleotides that can be used in an amplification reaction to allow amplification. Usually, a primer possesses a sequence that is complementary to the extremities of the polynucleotide sequence to be amplified. Generally speaking, in the sense primer case, multiple mutations are tolerated at the 5 'end rather than the 3' end of the primer (the 3 'end being a specific strand of nucleotide sequence for the sequence to be amplified). Required to hybridize completely). In the case of the antisense primer, it is the 3 'end that is tolerated. In certain embodiments, amplification does not result in the presence of many aspecific bands. By increasing the length of the primer and using strong conditions for amplification, the specificity of the hybridization is increased and the parasitic bands can be eliminated.

  In a particular embodiment, the primers are selected in all or part of the gene gs2018 of the GB-17 strain of ST-17 clone (especially deposited at CNCM number I-3537). Preferably the primer is a fragment of gene gbs2018 of this strain, more preferably a fragment of segment S10 or segment S11 of said gene. Usually, the primer has a size in the range of 10-30, preferably 15-30, more preferably 20-30 and even more preferably 20-25 nucleotides. In a preferred embodiment of the present invention, the primer is selected from ST-17S of SEQ ID NO: 33, ST-17AS of SEQ ID NO: 34, O11 of SEQ ID NO: 27, O12 of SEQ ID NO: 28, and O13 of SEQ ID NO: 29.

  The present invention also relates to an amplification product (amplimer or amplicon) comprising a product obtained by amplifying the DNA of the GBS strain of ST-17 clone with the primer set of the present invention or containing the product.

  “Amplification product” as used therein includes any chemical method, any synthesis method, any recombinant method, any ex vivo method, etc., and combinations thereof, It means a polynucleotide obtained by any known method without being limited thereto. In certain embodiments, these methods may include cloning, amplification, or chemical synthesis.

In certain embodiments, “amplification product” refers to a polynucleotide selected from:
The polynucleotide of sequence ST-17S / ST-17AS (Figure 5a) of SEQ ID NO: 35 obtained with a primer set consisting of ST-17S of SEQ ID NO: 33 and ST-17AS of SEQ ID NO: 34;
The polynucleotide of SEQ ID NO: 36 sequence O13 / ST-17AS (Figure 5b) obtained with a primer set consisting of O13 of SEQ ID NO: 29 and ST17-AS of SEQ ID NO: 34;
A polynucleotide of SEQ ID NO: 37 sequence O13 / O12 (Figure 5c) obtained with a primer set consisting of O13 of SEQ ID NO: 29 and O12 of SEQ ID NO: 28;
A polynucleotide of sequence ST-17S / O12 (FIG. 5d) of SEQ ID NO: 38 obtained with a primer set consisting of ST-17S of SEQ ID NO: 33 and O12 of SEQ ID NO: 28;
The polynucleotide of SEQ ID NO: 39, sequence O11 / ST-17AS (Figure 5e), obtained with a primer set consisting of O11 of SEQ ID NO: 27 and ST17-AS of SEQ ID NO: 34;
The polynucleotide of sequence O11 / O12 of FIG. 5 (FIG. 5f) obtained with a primer set consisting of O11 of SEQ ID NO: 27 and O12 of SEQ ID NO: 28;
In a preferred embodiment, the “amplification product” is the sequence ST-17S / ST-17AS of SEQ ID NO: 35 obtained after PCR amplification with the ST-17S of SEQ ID NO: 33 and the ST-17AS of SEQ ID NO: 34 (FIG. 5a). ) Polynucleotide.

   The invention also relates to a recombinant or chimeric polynucleotide comprising a polynucleotide according to the invention and a heterologous polynucleotide. A heterologous polynucleotide is one that is not naturally associated with the polynucleotide of the present invention. It is in particular a polynucleotide derived from another region of the gbs2018 gene or from another gene of the GBS strain or from another source.

  The polynucleotides can be labeled in any suitable manner that allows their recognition. Labeling means also include insertion of nucleotides for detection.

  The invention also relates to a kit for the in vitro detection of infection by GBS strains in a biological sample, which comprises a defined primer set and means for detecting the amplification product obtained with said primer set.

Certain kits of the invention further comprise a primer set suitable for amplification of GBS strain DNA, said primer set comprising or consisting of at least two oligonucleotides, wherein at least one oligonucleotide The oligonucleotide is a sense primer, at least one oligonucleotide is an antisense primer, and said oligonucleotide is selected from:
DltRS having the sequence of SEQ ID NO: 31;
DltRAS having the sequence of SEQ ID NO: 32;
O1 having the sequence of SEQ ID NO: 17;
O2 having the sequence of SEQ ID NO: 18;
O3 having the sequence of SEQ ID NO: 19;
O4 having the sequence of SEQ ID NO: 20;
O5 having the sequence of SEQ ID NO: 21;
O6 having the sequence of SEQ ID NO: 22;
O7 having the sequence of SEQ ID NO: 23;
O8 having the sequence of SEQ ID NO: 24;
O9 having the sequence of SEQ ID NO: 25;
O10 having the sequence of SEQ ID NO: 26;
O14 having the sequence of SEQ ID NO: 30;
As used herein, the term “kit” refers to a set of elements that are suitable for detecting infection by GBS strains of ST-17 clones in a biological sample. In particular, the kit according to the invention comprises all elements necessary and sufficient to allow detection of at least the ST-17 GBS strain (eg one or more isolated polynucleotide sequences and detection procedures according to the invention). Appropriate reagents required for the execution of).

  In certain embodiments, detection is accomplished via an amplification operation, and the reagents include, but are not limited to, a DNA polymerase, four different nucleoside triphosphates, and a reaction medium. In a preferred embodiment, the kit comprises at least one set of primers according to the invention corresponding to those defined above.

  In another embodiment, the kit comprises at least one probe corresponding to the polynucleotide of the invention, which probe may be a cold probe or labeled (especially by radioactivity). Often, it has the ability to specifically hybridize in a labeled or unlabeled form with the nucleic acid sequence (s) to be detected.

  In a particular embodiment, the probe is selected from all or part of the gbs2018 gene of the GBS strain of ST-17 clone. The probe is a fragment of gbs2018 gene of GBS strain of ST-17 clone, more preferably a fragment of segment S10 or segment S11 of the gene. Usually the probe has a size ranging from 10 to 700, especially 50 to 700, or alternatively 10 to 50 or 10 to 100, or 100 to 500, or 200 to 500 or even 200 to 300 nucleotides.

  In certain embodiments of the invention, the probe comprises the following polynucleotides: ST-17S of SEQ ID NO: 33, ST-17AS of SEQ ID NO: 34, O11 of SEQ ID NO: 27, O12 of SEQ ID NO: 28, and SEQ ID NO: Selected from 29 O13.

  In a preferred embodiment, the kit may comprise at least one positive and / or one negative control that allows the user to check the validity of the detection results. In one example, a negative control can include, but is not limited to, water, buffer, or any non-ST-17 GBS microorganism, such as a bacterium, virus or parasite, or its nucleic acid sequence. . By “non-ST-17 organisms”, culture methods and molecular techniques (eg multidentate enzyme electrophoresis (MLEE), multidentate sequencing classification (MLST), pulsed field gel electrophoresis) Meaning organisms not identified as GBS strains of ST-17 clones using known detection methods including electrophoresis (PFGE), restriction digestion patterns, restriction fragment length polymorphisms (RFLP) and combinations thereof) The

  Positive controls can include, but are not limited to, any of the above defined polynucleotides of the invention and organisms containing any of the polynucleotides of the invention.

  Optionally, the kit may further comprise elements necessary for the extraction of biological samples (eg extraction tools such as needles and syringes, collection containers, and combinations thereof, and possibly combinations) Instructions for use). By biological sample is meant a sample taken from any biological organism (preferably a mammalian organism, more preferably a human and most preferably a pregnant woman or a newborn). In preferred embodiments, the biological sample originates from a bodily fluid, such as serum, blood, or mucosal secretions, such as mucosa (eg, nasal, oral, gastrointestinal, vaginal or anal membranes). It is a secretion.

  Optionally, the kit may further comprise elements necessary for the detection of PCR amplification products. As an example, PCR products can be detected using standard intercalant agents such as BET or SYBR Green after separation by agarose gel electrophoresis [Huang et al., 2005]. In a further embodiment, amplification products are obtained by real-time PCR and detected with non-specific fluorescent intercalant agents (eg SYBR Green) [Whitcombe D et al., 1999]. In another embodiment, the amplification product is obtained by real-time PCR and a specific fluorescent probe, such as the Taqman system [Holland PM et al., 1991], the Molecular Beacon system [Tyagi S et al., 1996], or FRET Detected by use of the (fluorescence resonance energy transfer) system [Wittwer CT et al., 1997].

  The present invention also relates to a method for in vitro detection of a highly pathogenic GBS strain of ST-17 clone, which method detects gbs2018 gene or a fragment thereof in a biological sample, or a DNA product derived from the gene. Prepare for that. In certain embodiments, the method comprises detecting the S10 segment and / or the S11 segment of the gbs2018 gene.

  A particular method for the detection comprises amplifying the gbs2018 gene or a specific fragment thereof or a DNA product derived from said gene.

  A particular method for said detection comprises the step of elongating the gbs2018 gene or a specific fragment thereof or a DNA product derived from said gene.

In such a method, the step of amplification or extension involves the use of a primer set, preferably comprising at least one of the following primer pairs or consisting of at least one of the following primer pairs:
a) ST-17S having the sequence of SEQ ID NO: 33 and ST-17AS having the sequence of SEQ ID NO: 34;
b) O1 having the sequence of SEQ ID NO: 17 and O12 having the sequence of SEQ ID NO: 28;
c) O11 having the sequence of SEQ ID NO: 27 and O12 having the sequence of SEQ ID NO: 28;
d) O13 having the sequence of SEQ ID NO: 29 and O8 having the sequence of SEQ ID NO: 24;
e) O9 having the sequence of SEQ ID NO: 25 and O14 having the sequence of SEQ ID NO: 30;
f) O9 having the sequence of SEQ ID NO: 25 and O2 having the sequence of SEQ ID NO: 18;
g) ST-17S having the sequence of SEQ ID NO: 33 and O12 having the sequence of SEQ ID NO: 28;
h) O12 having the sequence of SEQ ID NO: 28 and O13 having the sequence of SEQ ID NO: 29;
i) O11 having the sequence of SEQ ID NO: 27 and ST-17AS having the sequence of SEQ ID NO: 34;
j) O13 having the sequence of SEQ ID NO: 29 and ST-17AS having the sequence of SEQ ID NO: 34;
k) a primer pair substantially complementary to the primers in a) to j);
h) a primer pair suitable for targeting each polynucleotide to the gbs2018 gene of a ST-17 clone or a fragment thereof, the sequence comprising the S10 and / or S11 segment of the gene or a fragment of the segment, or Primer pairs for amplifying sequences consisting of the S10 and / or S11 segments of the gene or fragments of the segments.

  In a particular embodiment of the method, the amplification step or extension step comprises a primer set consisting of ST-17S having the sequence of SEQ ID NO: 33 and ST-17AS having the sequence of SEQ ID NO: 34. Use is involved.

  In certain aspects of the invention, amplification is performed by PCR. Other amplification methods can be used, such as SDA, SSSR, LCR, TMA, NASBA, etc.

  As used herein, “amplification” includes any chemical method, any synthetic method, any recombinant method, any ex vivo method, and the like, and combinations thereof. It means the replication of the target polynucleotide sequence by any known method, not limited to. In certain embodiments, these amplification methods may include cloning, PCR amplification, or chemical synthesis.

In a preferred embodiment, amplification means PCR amplification of the target polynucleotide sequence. Said PCR amplification is based on a cycle comprising the following steps:
Denaturation of the detected double stranded nucleic acid (this leads to the formation of a single stranded nucleic acid),
Hybridization of each of the nucleic acid strands obtained during the previous denaturation step with at least one primer according to the invention (wherein said nucleic acid strand is subjected to stringent hybridization conditions with at least one set of primers of the invention Done by placing in contact with)
Formation of DNA (initiated from the primer) complementary to the strand where the primer hybridizes in the presence of a polymerizing agent (DNA polymerase) and four different nucleoside triphosphates (dNTPs).

  Successive repetition of the above cycle leads to a greater number of formations than the previous denaturation step of the detected double stranded nucleic acid. The cycle is repeated a defined number to obtain an amplified target polynucleotide sequence in sufficient quantity to permit detection.

The polymerization agent used in the cycle extension step is a thermostable DNA polymerase (particularly Taq polymerase or any commercially available polymerase).

  It is clear that the conditions mentioned in the examples can be modified depending on the source of the biological sample, the length and sequence of the primers, or the final volume of the reaction mixture.

  Methods for detection include identification of DNA of a highly pathogenic GBS strain of ST-17 clone or identification of its DNA fragment, or of products derived from said DNA as a result of carrying out the method for detection of the present invention. Identification is required. ST-17 strain-specific genes that allow accurate discrimination between organisms (or nucleic acids thereof) containing alleles of gbs2018 and other strains and / or organisms (or nucleic acids thereof) Is preferable. In certain embodiments of the invention, the term “detection” refers to the specific identification of infections caused by GBS strains of ST-17 clones from biological samples. In a more specific embodiment, ST-17 clone strains can also be distinguished from other streptococcal strains (preferably from other GBS strains of serotype III) by detection. In an even more preferred embodiment, the GB-17 strain of ST-17 clones is detected exclusively, allowing the detection of other sequence types of GBS strains that are neither other streptococcal strains nor other microorganisms. There is no.

  In a particular embodiment of the invention, the detection is carried out in whole or in part of the specific gbs2018 gene allelic form from the GBS strain of the ST-17 clone [eg in particular a segment of the sequence S10 of SEQ ID NO: 5 (Figure 3b). S10, S11a of SEQ ID NO: 13 (S11a of FIG. 4a) and / or S11b of SEQ ID NO: 15 (S11b of FIG. 4b, or a nucleic acid sequence thereof) may be amplified. Such amplification procedures include any known method including, but not limited to, any chemical method, any synthesis method, any recombinant method, any ex vivo method, and the like, and combinations thereof. May be provided. In certain embodiments, these amplification methods may include cloning, PCR amplification, or chemical synthesis.

  In another embodiment, the detection may comprise a hybridization operation with a probe made from a polynucleotide of the invention or derived therefrom. In particular, the probe may be a whole or part of a specific gbs2018 gene allelic form from the GBS strain of the ST-17 clone (e.g., in particular, segment S10 of SEQ ID NO: 5 sequence S10 (Figure 3b), SEQ ID NO: 13 S11a of sequence S11a (FIG. 4a) or S11b of sequence number 15 of S11b (FIG. 4b), or a fragment thereof, or a fragment of a gene containing the S10 and / or S11 segment, or a nucleic acid sequence of the segment of the segment) Can be prepared from The hybridization operation mainly comprises the following steps: denature the target nucleic acid to be detected, contact the probe with the denatured nucleic acid, and recover the resulting hybrid (eg, non- With a washing step to remove specific associations). Hybridization conditions are those defined in this application and are those described above or in the examples.

  The method for detection may also comprise means and steps for visualizing the results of the amplification operation or the hybridization operation. Said visualization means are well known to those skilled in the art and are means capable of identifying chemical, enzymatic or biological labeling means and chemical, enzymatic or biological labeling, for example Including, but not limited to, cold labeling, radioactive labeling and fluorescent labeling.

  In certain embodiments of the invention, the detection method may optionally comprise biological sample extraction, separation, preparation, purification, and the like. In particular, the detection may optionally comprise a step involving the extraction of the nucleic acid to be detected contained in the biological sample. Where appropriate, the extraction / purification step may involve incubation of the nucleic acid with a reverse transcriptase (if the latter is in the form of RNA).

  The invention also relates to a polypeptide encoded by one of the polynucleotides of the invention as defined herein. In a particular embodiment of the invention, the polypeptide does not have the sequence Gbs2018-NEM318 (Figure 1) of SEQ ID NO: 2. Nonetheless, the present invention includes a fragment of a polypeptide encoded by one of the polynucleotides of the present invention and the use of or of said polypeptide as defined in this application.

  A specific polypeptide is a fragment having at least 6 amino acid residues, particularly a fragment containing an epitope of the Gbs2018 surface protein of a strain of ST-17 clone. In a particular embodiment, said fragment is a fragment of the Gbs2018 surface protein of a strain of the ST-17 clone having the sequence Gbs2018-NEM318 (Figure 1) of SEQ ID NO: 2.

According to one embodiment, said polypeptide is derived from a polypeptide region designated S10 of Gbs2018 protein of GBS strain of ST-17 clone and is selected from among the following:
A polypeptide S10 segment, in particular a polypeptide having the sequence S10 of SEQ ID NO: 6 (Figure 3b);
A fragment thereof (particularly a fragment having at least 6 amino acid residues and containing an epitope);
A polypeptide comprising the S10 segment, having at least 190 amino acid residues and having less than 550 or less than 300 or less than 250 amino acid residues.

  A particular fragment of the S10 polypeptide region having the sequence S10 of SEQ ID NO: 6 (FIG. 3b) is that recognized by an antibody against the Gbs2018 surface protein.

According to one embodiment, the polypeptide is derived from the polypeptide region designated S11 of the Gbs2018 protein of the GBS strain of ST-17 clone and is selected from among the following:
A polypeptide S11a segment, in particular a polypeptide having the sequence S11a of SEQ ID NO: 14 (Figure 4a);
A polypeptide S11b segment (especially a polypeptide having the sequence S11b of SEQ ID NO: 16 (FIG. 4b));
A fragment thereof (particularly a fragment having at least 6 amino acid residues and containing an epitope);
A polypeptide comprising said S11a segment and having at least 72 amino acid residues and having less than 550 or less than 300 or less than 250 amino acid residues;
A polypeptide comprising the S11b segment, having at least 79 amino acid residues and having less than 550 or less than 300 or less than 250 amino acid residues.

  A specific fragment of the S11a polypeptide region having the sequence S11a of SEQ ID NO: 14 (FIG. 4a) is one that is recognized by an antibody against the Gbs2018 surface protein.

  A particular fragment of the S11b polypeptide region having the sequence S11b of SEQ ID NO: 16 (FIG. 4b) is that which is recognized by an antibody against the Gbs2018 surface protein.

  The polypeptide of the present invention may comprise an epitope and may have 6-50, or 6-30, or 6-15 amino acids (this polypeptide has the ability to be recognized by antibodies to the Gbs2018 surface protein. ing).

  In certain embodiments, the polypeptide is derived from a strain of ST-17 clone and is not recognized by antibodies to Gbs2018 surface protein of other strains of GBS serotype III.

  The invention also relates to recombinant or chimeric polypeptides and heterologous polypeptides comprising a polypeptide as defined herein. A heterologous polypeptide is one that is not naturally associated with a polypeptide of the invention. It is in particular a polypeptide derived from another region of the Gbs2018 surface protein or from another surface protein of the GBS strain or from another source.

  The polypeptides of the present invention may be associated with a carrier molecule.

  Further, the present invention relates to a GBS surface protein of ST-17 clone of GBS strain [in particular, the surface protein having the sequence Gbs2018-NEM318 (FIG. 1) of SEQ ID NO: 2, or the S10 segment and / or the S11 segment. It is related with the antibody characterized by recognizing the containing fragment | piece]. Such fragments are defined above. In particular, these antibodies recognize the above polypeptides with higher affinity than other GBS surface proteins of other GBS strains or do not recognize such other GBS surface proteins.

  The present invention also relates to a method for preparing an antibody against a polypeptide as defined herein, the method comprising immunizing an animal with the polypeptide and an antibody produced against the polypeptide. Collecting.

  The present invention also relates to a monoclonal antibody against a polypeptide as defined herein, said monoclonal antibody comprising GBS surface protein of clone ST-17 of the GBS strain and in particular S10 segment and / or S11 (S11a and / or S11b) It specifically recognizes that fragment containing all or part of the segment. Such fragments are defined above.

  The present invention also relates to a fragment of an antibody as defined herein, wherein the fragment comprises or consists of all or part of a domain that is sufficiently variable to recognize and bind to the GBS surface protein. included.

  The present invention also relates to the use of a polypeptide as defined herein for the application as defined herein, in particular for in vitro infection of a GBS strain of a ST-17 clone, particularly in a biological sample. Gbs2018-NEM318 (FIG. 1) polypeptides for detection and use thereof are included.

  Kit for detecting in vitro infection by GBS strains in a biological sample comprising a polypeptide of the invention or an antibody or fragment thereof according to the invention, and the polypeptide or antibody or fragment thereof and the biological Means for detecting the antigen / antibody complex obtained in the sample are also encompassed by the present invention.

  The polynucleotides, polypeptides, antibodies and fragments thereof, methods, kits according to the invention are suitable for use in the detection of strains of ST-17 clones in mammals and / or humans.

  The polynucleotides, polypeptides, antibodies and fragments thereof, methods, kits according to the invention are particularly suitable for use in detecting strains of ST-17 clones in pregnant women, embryos, fetuses, newborns and / or children It is.

  Polynucleotides, polypeptides, antibodies and fragments thereof, methods, kits disclosed in the present invention are invasive infections, neonatal mortality or neonates caused by strains of GB-17 strain ST-17 clone Is a means for use in detecting morbidity.

  The polynucleotides, polypeptides, antibodies and fragments thereof, methods and kits according to the present invention are suitable for use in detecting neonatal pneumonia, bacteremia or meningitis caused by strains of ST-17 clone of GBS strain .

  Other features of the invention will be apparent from the examples and drawings, and may be applied individually or in combination to the disclosed elements of the invention described above.

  The drawings in this application are provided for purposes of illustration and do not limit the subject matter of the invention.

[Example]
The following examples and corresponding drawings are provided to illustrate the invention and do not limit the scope of the invention. In a similar manner, the specific means disclosed in the examples are suitable for applying to the above elements.

  Example 1: GBS strain identification, serotyping and DNA extraction.

  To characterize the gbs2018 gene, three sequenced strains NEM316 serotype III, 2603V / R serotype V, strain A909 serotype Ib (http://www.tigr.org/tdb/mdb/ mdbinprogress.html), 181 unrelated GBS strains, including partially sequenced serotype III strain COH1 and characterized serotype III strain BM110 were studied.

  The collection includes 155 human strains from various French geographical origins isolated between 1990 and 2005, various UK geographies, as detailed in Table 1 described below. 8 strains from common sources and 13 bovine mastitis strains are included.

  Identification of the GBS strain was achieved using a commercially available latex agglutination test (bio Merieux, Marcy l'Etoile, France). The strain was then serotyped by aggregation using a commercial kit from Essum (Umea, Sweden). All GBS strains were cultured on Columbia agar containing 5% horse blood at 37 ° C in 5% CO2 atmosphere. The corresponding stored cultures were then frozen and stored at -80 ° C in Todd-Hewitt broth containing 10% glycerol.

  DNA was extracted from bacterial cultures and clinical samples of 16 clinical isolates representing different STs.

Extraction of total DNA from overnight bacterial colonies was performed by using InstaGene ^™ Matrix (Bio-Rad, Hercules, CA).

DNA from vaginal samples was extracted as described in Reglier-Poupet et al., 2005. In summary, mucosal secretions of the lower third of the vagina were obtained with a cotton swab. The same specimen was used for standard culture and PCR assays. The swab was released in 500 μl sterile PBS and vortexed. For the microbiological culture and identification of GBS, 100 μl was seeded on Columbia horse blood agar plates and incubated at 37 ° C. with 5% CO 2 for 18 h. β-hemolytic colonies and suspected non-hemolytic colonies were identified as GBS by using a commercially available latex agglutination test (bioMerieux). For PCR assays, the remaining 400 μl was immediately frozen at −80 ° C. until extraction. One hundred microliters of frozen samples were prepared as crude lysates using a commercial DNA extraction kit according to the manufacturer's protocol (QIAamp DNA minikits, Qiagen Courtaboeuf, France).

Example 2: Identification and characterization of gbs2018 polymorphism The extracted DNA was used as a matrix for PCR amplification. Full length genes of all allelic forms of gbs2018 were amplified using primer pair O1-O2 (see Table S1 below) (localized upstream and downstream of said gene, respectively).

  Sau3A-RFLP analysis of the PCR product revealed considerable structural heterogeneity at the gbs2018 locus, simply due to intramolecular rearrangement (deletion / amplification) within the KPEA repeat segment present in NEM316 Absent.

  To understand the genetic diversity of the gbs2018 allele, all 16 PCR fragments were globally sequenced with corresponding PCR primers on both strands (see primers O1-O14 in Table S1). . The resulting DNA sequence was assembled using “Codoncode Aligner version 1.3.4” software to obtain the full length gbs2018 gene. The DNA sequences were then analyzed and compared with “DNA Strider version 1.4f3” and “Clustal X version 1.83”. Finally, a phylogenetic tree was created from the gbs2018 sequence alignment using the neighbor-joining method with the “TreeEdit version 1.01a10” software.

  As shown in FIG. 6, the resulting phylogenetic tree contained the sequenced strains NEM316, 2603V / R, and A909 gbs2018 gene. In the latter strain, the gbs2018-like sequence was interrupted by the insertion sequence IS1381. In order to avoid the occurrence of an abnormal phylogenetic tree, the inserted sequence was excluded from this analysis. Therefore, the sequence A909 delta was reconstituted in silico. In addition, the star ST-19 * means one mutation in one of the seven genes analyzed when compared to the reference sequence. The DNA sequences assigned to each cluster (A, B, and C) have different properties. On the other hand, sequence variations within a given cluster are primarily due to rearrangements within segments that contain repetitive sequences (see Figure 6).

The resulting phylogenetic tree revealed the existence of three major clusters, called A, B, and C:
Cluster A is divided into four sublines and contains gbs2018 sequences from strains belonging to ST-19 and ST-23, in particular gbs2018 sequences from the sequenced strains 2603 V / R and NEM316.

      Cluster B is a sequence from strains belonging to 8 different STs (ST-1, ST-2, ST-7, ST-6, ST-8, ST-9, ST-10, and ST-41) Among them, three sublines were identified.

      Importantly, cluster C (which contains two substrains) was shown to consist exclusively of ST-17 sequences. To confirm this observation, gbs2018 variants from 11 additional ST-17 GBS strains were sequenced and proved to belong to cluster C.

  The structure of the gbs2018 gene variant was analyzed in detail by using representatives of clusters A (NEM316), B (NEM1010) and C (BM110) as prototype sequences (see FIG. 7). Based on sequence analysis, representative members of each phylogenetic cluster A, B, and C encoding three allelic forms of the surface protein Gbs2018 are eleven segments (numbered S1-S11). Divided).

Of the eleven segments specified, three are present in all sequences:
5 'segment S1 (encodes signal peptide);
3 ′ segment S8 (encoding a localization signal consisting of a “LPXTG” motif followed by a hydrophobic domain and a positively charged tail) and;
Segment S7, which contains a variable number (n) of repeats encoding a 4-amino acid long motif based on the sequence “KPEA”; n ranges between 54 and 126 in clusters A and B and in cluster C n = 45).

  Sequence variations within a given cluster proved to be mainly due to rearrangement of the part containing the repetitive sequence. Thus, sequence heterogeneity within cluster A appears to be linked to variations in the number of KPEA repeats in S7 (CCH180, NEM1002) or to deletions that remove the S6 segment. Indeed, segment 6 was surprisingly absent in the gbs2018 gene of the three ST-19 strains (cluster A) analyzed in this study (2603V / R, NEM940, NEM1560). This deletion appears to be due to a recombination event between segments S5 and S7 that share 84% identity beyond 36 bp.

  In cluster B, sequence diversity appears to correlate with size variation in segment S7. On the other hand, the two sublines observed in cluster C are probably due to the number of S11 repeats in gbs2018.

Finally, each cluster was found to contain at least one distinct segment, ie:
Segment S3 appears to be unique to cluster A;
Segment S9 (containing 9 repeats encoding an 8-amino acid long motif based on the sequence “IKAESINT / K”) was found only in cluster B;
Segments S10 and S11 appear to be specific for cluster C. Surprisingly, two copies of segment S11 (consisting of segment S11b following segment S11a) are found in all, but not in the two ST-17 strains belonging to cluster C (COH1 and NEM318) .

Example 3: Development of a real-time PCR assay to specifically detect GBS strains and ST17 variants in clinical samples The specific primers dltRS and dltRAS were designed to detect GBS strains by PCR. Indeed, this couple of primers allows amplification of the 234-bp fragment in the presence of dltR [single copy regulatory gene specifically encountered in S. agalactiae] [Poyart C. et al., 2001].

  Based on the gbs2018 polymorphism observed in Example 2 above, ST-17 specific primers ST-17A and ST-17AS were designed using the sequence of the C cluster specific S10 domain (which gbs2018 specific segment S10 to 210-bp amplicon fragments will be generated).

  In both cases, optimized primer sequences were designed with “Beacon Designer 4.01”. The sequences were then compared against the Genbank database using a BLAST search to verify the absence of serendipitous similarities.

  Real-time PCR assays that enable detection of GBS strains and ST-17 variants from isolated colonies or from clinical samples using primer pairs ST-17A / ST-17AS and dltRS / dltRAS are performed in separate reactions. It was.

  PCR assays were performed on a LightCycler® 2.0 instrument (Roche Molecular Diagnostics) with 5 μl extracted DNA or distilled water (negative control), 0.45 mM sense and antisense primers, 2 μl 10X LightCycler-DNA Master Performed in a final volume of 25 μl containing SYBR Green I (Roche Molecular Biochemicals, Mannheim, Germany) and 4.0 mM MgCl 2.

  The PCR mixture was subjected to a 95 ° C, 10 min precycle. Amplification was performed using 40 cycles of 95 ° C for 10 sec, 5 sec for 10 sec at 55 ° C and 72 ° C. At the end of the 40 amplification cycles, the reaction was heated to 95 ° C and then cooled to 35 ° C. The reaction products were subjected to a post-PCR melting cycle or analyzed by agarose gel electrophoresis.

  The melting profile was performed using the software program provided with the LightCycler instrument (Version 4.0). In the LightCycler, a positive result for the ST-17 GBS strain produced two curves with melting temperatures (Tm) 79.5 + 0.4 (dltR) and 78.5 + 0.3 (ST-17), respectively. On the other hand, the non-ST-17 GBS strain produced a single melting curve with Tm 79.5 + 0.4.

Positive and negative controls were included in all experiments:
DNA extracted from the reference strain S. agalactiae BM110 was used as a positive control; the analytical sensitivity of the method was assessed by serial 10-fold dilutions of BM110 genomic DNA. The standard / positive control was two dilutions corresponding to 10 ³ and 10 ¹ GBS bacterial genomes.

      As a negative control, water was added instead of DNA.

      The absence of inhibitors in all negative PCR samples was checked using an internal standard (where plasmid DNA is in the presence of specific primers Vlac1 and Vlac2 (see Table S1 above)). Was added at a final concentration of 10 copies / PCR reaction to allow amplification of a 125-bp DNA fragment].

  In addition, strict preliminary measures were taken to prevent cross-contamination: therefore, the treatments performed before and after the PCR operation were performed in separate rooms.

The specificity of the PCR assay was also verified using DNA extracted from pure cultures of various Gram positive and Gram negative bacterial species from the inventors' research collection. These include a number of normal intestinal and reproductive flora streptococci and other microorganisms as well as bacteria that cause genital infections (found in Table S2 below).

  Finally, a bacterial collection of 181 GBS strains was characterized by PCR using both primer pairs dltRS / dltRAS and ST-17S / ST-17AS in the same reaction. In this analysis, eight invasive clones previously identified as strain ST-17 were present as positive controls. The sequenced strains NEM316 (ST-23) and 2603V / R (ST-19 *) were then used as negative controls. As expected, primers dltRS / dltRAS produced the expected PCR fragments in all 181 GBS strains. On the other hand, primers ST-17A and ST-17AS produced positive reactions with 50 clinical human isolates. An example of the amplification pattern obtained with two couples of primers is shown in FIG.

In addition, all strains screened as PCR positive with the ST-17 primer were shown to belong to serotype III, and all but one were isolated from human invasive infection. (See Table 2 below). To evaluate the results obtained by amplification, MLST was performed on 42 strains, all of which were identified as ST-17 (Table 2). Similarly, MLST was performed on 61 remaining 131 ST-17 PCR negative strains. Among them, 19 neonatal invasive strains (11 strains from EOD, 7 strains from LOD, and one strain isolated from a 3-year-old child), 19 adult invasive strains, 11 Of carrier strains and 12 strains from bovine mastitis confirmed that they did not belong to ST-17.

  As shown in Table 2, the most frequently found ST among human strains was ST-23 (14 strains), followed by ST-19 (10 strains), ST-1 (6 strains) ST-8 (5 strains), ST-10 (6 strains), and ST-2 (3 strains); all other STs were represented by one strain.

Finally, 85 vaginal samples from pregnant women collected for the January period (December 2004) were collected from the conventional direct plate culture method with GBS detection and real-time PCR of the present invention. Analyzed by comparison using the assay:
The plate culture method identified 13 (15.2%) GBS positive cultures after 37 h at 24 h. The serotype distribution (number of strains) was III (5), Ia (2), and Ib (6).

      Real-time PCR assays performed on DNA extracted directly from vaginal samples confirmed that GBS was present in 13 samples and that the presence of the ST-17 strain was 2 samples. These results were further confirmed by MLST. Moreover, the PCR assay was negative for the remaining 72 samples. The absence of inhibitor was assessed using an internal PCR plasmid DNA control that produced a positive signal in all cases.

  We have therefore developed a real-time PCR assay that allows rapid, simple, reliable, and accurate detection of “highly pathogenic” GBS ST-17 strains in bacterial cultures or directly in vaginal secretions. Using this technique, accurate identification of women and newborns with ST-17 colonized can be easily achieved in less than two hours.

Example 4: Epidemiological report of group B streptococci: 58 strains responsible for invasive infections from different geographical regions of France were studied [ie, 28 unrelated neonatal invasive strains and adult invasive infections. 30 non-redundant strains isolated from]. All received strains are further assigned identification and confirmation of antimicrobial susceptibility characteristics, capsular serotype determination by PCR-based molecular serotyping (Poyart et al., 2006), and superpathogenicity by real-time PCR The characteristics were examined by detection of ST-17 clones (above and in Lamy et al., 2006).

I. Neonatal invasive infection Among the 58 isolates studied, 28 non-redundant strains were isolated from neonatal invasive disease. 16 and 12 of these strains are associated with early-onset disease (EOD; i.e. disease occurring up to 6 days) and late-onset disease (LOD, i.e. 7 to 3 days). Diseases occurring at age) (see Table 3).

  EOD strains: 10 (62.5%) of the 16 EOD strains were isolated from blood cultures. Two of them were isolated from blood cultures and cerebrospinal fluid. And the remaining 6 strains were from neonatal stomach samples with symptoms of neonatal infection (dyspnea, shock, and pneumonia). According to molecular capsular serotyping, 16 EOD isolates were serotype III (n = 8; 50%), Ia (n = 6; 37.5%), II (n = 1; 6.25%), or It became clear to belong to V (n = 1; 6.25%). Ten strains isolated from blood cultures were of serotypes Ia (n = 5, 50%), III (n = 4, 40%), and V (n = 1, 10%). Of these strains, the two strains responsible for meningitis were of serotypes Ia and III. Six strains from gastric juice belonged to serotype III (n = 4, 66.6%) and Ia (n = 2; 33.3%). PCR detection of ST-17 superpathogenic clones included 8 blood isolates (including one isolate responsible for meningitis) and 8 isolates including 3 isolates from gastric juice Positive for serotype III EOD strain.

LOD strains: All 12 LOD strains were isolated from blood cultures, belonged to serotype III and identified as CT-17 clones. Nine (75%) of these 12 isolates were recovered from CSF and were responsible for meningitis.

  These results demonstrated that the association between strain invasiveness and LOD newborn ST-17 strains was highly significant (p <.0001) (because all 12 invasions studied) This is because the sex strain was ST-17). In EOD, ST-17 clone complexes were identified as 8 out of 16 strains studied (50%) (p <.01), corresponding to 100% (n = 8) of serotype III strains . This confirmed that the majority of GBS isolates responsible for invasive infections in French newborns were ST-17. Similar results have been reported in other countries (Bisharat et al, 2004; Bohnsack et al, 2004; Jones et al, 2006; Lin et al, 2006).

II. Adult invasive infection
Thirty non-overlapping strains were isolated from adult invasive infections (two major clinical symptom sepsis and arthritis).

The characteristics of these strains are shown in Table 4.

  The most prevalent capsular serotypes were III (33.3%), Ia (26.6%), and V (26.6%). Of the 30 strains, fifteen (50%) were isolated from blood cultures and nine (30%) were responsible for arthritis and were isolated from articular punctions. No dominance of the capsular serotype was found among the strains causing bacteremia and arthritis. Three of the 30 strains studied were responsible for meningitis (two serotype III and one serotype Ia strain). Of the ten serotype III isolates in this collection, only two were identified as ST-17 (20%), none of which was responsible for meningitis.

  These results demonstrated that the epidemiology of the GBS strain responsible for adult invasive infection is dramatically different from that observed in neonates.

III. Prevalence of hypervirulent ST-17 clones of serotype III isolated from vaginal samples
Cochin during a one-year period (1/06/05 to 1/06/06) to study the prevalence of superpathogenic ST-17 clones in GBS colonized in the vagina of pregnant women All GBS strains isolated from vaginal samples taken from pregnant women in the hospital were studied. All serotype III GBS detected by the agglutination method were confirmed by molecular serotyping. PCR detection of ST-17 clones was performed on all serotype III strains whose serotyping was confirmed by molecular technology. The results obtained are shown in Table 5.

A total of 3235 non-redundant vaginal samples were analyzed. 325 were positive for GBS, of which 113 strains were serotype III (35%). Of the 113 serotype III strains, 47 (41.6%) were ST-17. In conclusion, GBS carriage was detected in 10% of pregnant women studied. And serotype III strain was present in 34.76% of women with colonies. The percentage of ST-17 clones in this serotype III GBS population was 41.6%.

  It is noted that the epidemiological characteristics (serotype and prevalence of ST-17) of pregnant women and EOD GBS strains are almost identical (see Table 3 and Table 5). This observation provides further indications to our proposal that detection of the highly pathogenic clone ST-17 in the vaginal sample should be done to assure accurate tracking of the colonized infant. It was.

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Claims (55)

A polynucleotide selected from the following group:
a) A group B streptococcal gene encoding the surface protein Gbs2018 of the strain of the ST-17 clone, comprising a nucleic acid sequence having the sequence S10 of SEQ ID NO: 5, and at least one SEQ ID NO: 13 A gene comprising a domain consisting of at least one nucleic acid sequence having the sequence S11a and / or the sequence S11b of SEQ ID NO: 15;
b) a polynucleotide that hybridizes with the gene of a) under stringent conditions;
c) a fragment derived from the group B streptococcus gene of a) or a corresponding fragment derived from a polynucleotide that hybridizes with the gene defined in a) under stringent conditions, the GBS strain of ST-17 clone A fragment encoding a polypeptide that is suitable for use in a method for the specific detection of or comprising an epitope of said Gbs2018 surface protein;
d) a polynucleotide substantially complementary to a fragment of the gene defined in a) or of the polynucleotide defined in b) or of the fragment defined in c), which is specific for the GBS strain of the ST-17 clone A polynucleotide encoding a polypeptide suitable for use in a method for complete detection or comprising an epitope of said Gbs2018 surface protein;
e) However, the polynucleotide does not consist of a polynucleotide having the coding sequence of SEQ ID NO: 1. The polynucleotide of claim 1, wherein the polynucleotide is selected from the following group:
a) a Group B Streptococcus gene encoding the Gbs2018 surface protein of a strain of ST-17 clone, said gene comprising the nucleic acid sequence of the S10 segment having SEQ ID NO: 5, and at least two The nucleic acid sequence of the S11a segment of SEQ ID NO: 13 or the nucleic acid sequence of the S11b segment of SEQ ID NO: 15 or at least one nucleic acid sequence having at least one copy of each of the nucleic acid sequences of SEQ ID NO: 13 and SEQ ID NO: 15 A gene comprising a domain consisting of;
b) A polynucleotide that hybridizes with the gene of a) under stringent conditions (including those that hybridize with two identical or different segments selected from the group of S10 segment and S11a segment and S11b segment) Is);
c) A fragment derived from the group B Streptococcus gene defined in a) or a fragment derived from a polynucleotide that hybridizes with the gene under stringent conditions, and is specific to the GBS strain of the ST-17 clone A fragment encoding a polypeptide suitable for use in a method for detection or comprising an epitope of said Gbs2018 surface protein;
d) a polynucleotide substantially complementary to a fragment of the gene defined in a) or of the polynucleotide defined in b) or of the fragment defined in c), which is specific for the GBS strain of the ST-17 clone A polynucleotide encoding a polypeptide that is suitable for use in a method for complete detection or that comprises an epitope of said Gbs2018 surface protein. A polynucleotide according to claim 1 or 2, which is a fragment of the gbs2018 gene having SEQ ID NO: 1 suitable for use in a method for the specific detection of GBS strains of ST-17 clones. nucleotide. The fragment according to any one of claims 1 to 3, derived from an S10 segment having a nucleotide sequence of SEQ ID NO: 5 in the gbs2018 gene of a strain of ST-17 clone, wherein the fragment is at least 10 nucleotides A polynucleotide having The polynucleotide of claim 4, wherein the polynucleotide is a fragment derived from the S10 segment having the sequence of SEQ ID NO: 5, which fragment is suitable for use in a method for the specific detection of GBS strains of ST-17 clones. . 6. The polynucleotide of any one of claims 1-5, wherein the DNA fragment is derived from the gene having 10-30, in particular 15-30, in particular 20-30, or 20-25 nucleotides. A polynucleotide which is 6. DNA fragment derived from said gene having 10-700, in particular 50-700 or 100-500, in particular 200-500, or 200-300 nucleotides. Polynucleotides. The polynucleotide of claim 6, wherein the polynucleotide is selected from:
a) a polynucleotide having SEQ ID NO: 33;
b) a polynucleotide having SEQ ID NO: 34;
c) a polynucleotide having SEQ ID NO: 27;
d) a polynucleotide having SEQ ID NO: 28;
e) a polynucleotide having SEQ ID NO: 29;
f) a polynucleotide (particularly a polynucleotide comprising SEQ ID NO: 35) which is an amplification product obtained when the DNA of GBS strain is amplified with a primer set comprising SEQ ID NO: 33 and SEQ ID NO: 34;
g) a polynucleotide that is an amplification product obtained by amplifying the DNA of GBS strain with a primer set consisting of SEQ ID NO: 29 and SEQ ID NO: 34 (particularly a polynucleotide consisting of SEQ ID NO: 36);
h) A polynucleotide (in particular, a polynucleotide comprising SEQ ID NO: 37) which is an amplification product obtained when the DNA of GBS strain is amplified with a primer set comprising SEQ ID NO: 29 and SEQ ID NO: 28;
i) A polynucleotide (in particular, a polynucleotide comprising SEQ ID NO: 38) which is an amplification product obtained when the DNA of GBS strain is amplified with a primer set comprising SEQ ID NO: 33 and SEQ ID NO: 28;
j) a polynucleotide that is an amplification product obtained by amplifying the GBS strain DNA with a primer set comprising SEQ ID NO: 27 and SEQ ID NO: 34 (particularly a polynucleotide comprising SEQ ID NO: 39);
k) a polynucleotide which is an amplification product obtained by amplifying the GBS strain DNA with a primer set comprising SEQ ID NO: 27 and SEQ ID NO: 28 (particularly a polynucleotide comprising SEQ ID NO: 40);
l) a polynucleotide which is substantially the complement of one of polynucleotides a) to k);
m) a polynucleotide that hybridizes with the polynucleotide of l) under stringent conditions;
n) a polynucleotide suitable for targeting the gbs2018 gene of ST-17 clone or a fragment thereof, comprising a sequence comprising the S10 and / or S11 segment of said gene or S10 and / or S11 of said gene A polynucleotide for amplifying a sequence consisting of segments. A polynucleotide according to any one of claims 1 to 3, derived from a copy of a segment designated S11a or a copy of a segment designated S11b in the gbs2018 gene of a strain of an ST-17 clone. 10. The polynucleotide of claim 9, wherein a copy of the S11a segment has the sequence of SEQ ID NO: 13 or a copy of the S11b segment has the sequence of SEQ ID NO: 15. ST-17 A primer set suitable for use in a method for detection of clone GBS strain DNA or for detection of a product derived from such DNA, comprising the following primer pairs or: Paired primer set:
a) ST-17S having the sequence of SEQ ID NO: 33 and ST-17AS having the sequence of SEQ ID NO: 34;
b) ST-17S having the sequence of SEQ ID NO: 33 and O12 having the sequence of SEQ ID NO: 28;
c) O11 having the sequence of SEQ ID NO: 27 and O12 having the sequence of SEQ ID NO: 28;
d) O12 having the sequence of SEQ ID NO: 28 and O13 having the sequence of SEQ ID NO: 29;
e) O11 having the sequence of SEQ ID NO: 27 and ST-17AS having the sequence of SEQ ID NO: 34;
f) O13 having the sequence of SEQ ID NO: 29 and ST-17AS having the sequence of SEQ ID NO: 34;
g) a primer pair substantially complementary to the primers in a) to f);
h) a primer pair suitable for targeting the gbs2018 gene or fragment thereof of each ST-17 clone, wherein each polynucleotide comprises a sequence comprising the S10 and / or S11 segment of the gene or S10 and Primer pair for amplifying sequences consisting of S11 segments. 12. The primer pair according to claim 11, comprising ST-17S having the sequence of SEQ ID NO: 33 and ST-17AS having the sequence of SEQ ID NO: 34. An amplimer comprising an amplification product of the primer set according to claim 11 or 12 of the DNA of the GBS strain of ST-17 clone. The amplimer according to claim 13, wherein the amplification product is selected from:
The polynucleotide of sequence ST-17S / ST-17AS (Figure 5a) of SEQ ID NO: 35 obtained with a primer set consisting of ST-17S of SEQ ID NO: 33 and ST-17AS of SEQ ID NO: 34;
The polynucleotide of SEQ ID NO: 36 sequence O13 / ST-17AS (Figure 5b) obtained with a primer set consisting of O13 of SEQ ID NO: 29 and ST17-AS of SEQ ID NO: 34;
A polynucleotide of SEQ ID NO: 37 sequence O13 / O12 (Figure 5c) obtained with a primer set consisting of O13 of SEQ ID NO: 29 and O12 of SEQ ID NO: 28;
A polynucleotide of sequence ST-17S / O12 (FIG. 5d) of SEQ ID NO: 38 obtained with a primer set consisting of ST-17S of SEQ ID NO: 33 and O12 of SEQ ID NO: 28;
The polynucleotide of SEQ ID NO: 39, sequence O11 / ST-17AS (Figure 5e), obtained with a primer set consisting of O11 of SEQ ID NO: 27 and ST17-AS of SEQ ID NO: 34;
The polynucleotide of sequence O11 / O12 (FIG. 5f) of SEQ ID NO: 40 obtained with a primer set consisting of O11 of SEQ ID NO: 27 and O12 of SEQ ID NO: 28. 15. The polynucleotide according to any one of claims 1 to 14, which is labeled. A recombinant or chimeric polynucleotide comprising the polynucleotide of any one of claims 1 to 15 and a heterologous polynucleotide. A kit for in vitro detection of infection by a GBS strain in a biological sample for detecting the primer set according to any one of claims 11 and 12 and the amplification product obtained with the primer set. A kit comprising means. A kit for in vitro detection of infection by GBS strain in a biological sample, wherein each primer is a polynucleotide sequence according to any one of claims 6 or 7 and obtained with said primer set A kit comprising means for detecting the amplified product. The kit according to claim 17 or 18, further comprising a primer set suitable for amplifying the DNA of GBS strain, wherein the primer set comprises at least two oligonucleotides or consists of at least two oligonucleotides, Wherein at least one oligonucleotide is a sense primer, at least one oligonucleotide is an antisense primer, and said oligonucleotide is selected from:
DltRS having the sequence of SEQ ID NO: 31;
DltRAS having the sequence of SEQ ID NO: 32;
O1 having the sequence of SEQ ID NO: 17;
O2 having the sequence of SEQ ID NO: 18;
O3 having the sequence of SEQ ID NO: 19;
O4 having the sequence of SEQ ID NO: 20;
O5 having the sequence of SEQ ID NO: 21;
O6 having the sequence of SEQ ID NO: 22;
O7 having the sequence of SEQ ID NO: 23;
O8 having the sequence of SEQ ID NO: 24;
O9 having the sequence of SEQ ID NO: 25;
O10 having the sequence of SEQ ID NO: 26;
O14 having the sequence of SEQ ID NO: 30. A method for in vitro detection of a highly pathogenic GBS strain of clone ST-17, the method for detecting in vitro a highly pathogenic GBS strain of ST-17 clone, said method comprising gbs2018 gene in a biological sample Or detecting a fragment thereof, or a DNA product derived from said gene. 21. The method of claim 20 for in vitro detection of a highly pathogenic GBS strain of clone ST-17, comprising detecting segment S10 and / or the segment S11, or a fragment thereof, in a biological sample Method. The method according to claim 20 or 21, comprising a step of amplifying the gbs2018 gene or a specific fragment thereof or a DNA product derived from the gene. 23. The method according to claim 22, wherein the amplification step uses a primer set in which each primer includes or consists of the polynucleotide sequence according to any one of claims 6, 7 or 8. Including methods. 23. The method according to claim 22, wherein the amplification step comprises using a primer set comprising at least one of the following primer pairs or consisting of at least one of the following primer pairs.
a) ST-17S having the sequence of SEQ ID NO: 33 and ST-17AS having the sequence of SEQ ID NO: 34;
b) O1 having the sequence of SEQ ID NO: 27 and O12 having the sequence of SEQ ID NO: 28;
c) O11 having the sequence of SEQ ID NO: 27 and O12 having the sequence of SEQ ID NO: 28;
d) O13 having the sequence of SEQ ID NO: 29 and O8 having the sequence of SEQ ID NO: 24;
e) O9 having the sequence of SEQ ID NO: 25 and O14 having the sequence of SEQ ID NO: 30;
f) O9 having the sequence of SEQ ID NO: 25 and O2 having the sequence of SEQ ID NO: 18;
g) ST-17S having the sequence of SEQ ID NO: 33 and O12 having the sequence of SEQ ID NO: 28;
h) O12 having the sequence of SEQ ID NO: 28 and O13 having the sequence of SEQ ID NO: 29;
i) O11 having the sequence of SEQ ID NO: 27 and ST-17AS having the sequence of SEQ ID NO: 34;
j) O13 having the sequence of SEQ ID NO: 29 and ST-17AS having the sequence of SEQ ID NO: 34;
k) a primer pair substantially complementary to the primers in a) to j);
l) a primer pair suitable for targeting each gbs2018 gene ST-17 clone or fragment thereof, wherein each polynucleotide is a sequence comprising the S10 and / or S11 segment of said gene or S10 and / or said gene Or a primer pair for amplifying the sequence consisting of the S11 segment. 23. The method of claim 22, wherein the amplification step comprises using a primer set consisting of:
a) ST-17S having the sequence of SEQ ID NO: 33 and ST-17AS having the sequence of SEQ ID NO: 34; 26. The method according to any one of claims 22 to 25, wherein the amplification is performed by PCR. 27. A method according to any one of claims 20 to 26, wherein the biological sample is obtained from a mammal, in particular a human patient. 28. A method according to any one of claims 20 to 27, wherein the biological sample is derived from a pregnant woman, an embryo, a fetus, a newborn and / or a child. 29. A method according to any one of claims 20 to 28 for use in the detection of neonatal invasive infection, wherein the infection is caused by a strain of the ST-17 clone of the GBS strain. 30. A method according to any one of claims 20 to 29 for use in detecting neonatal pneumonia, bacteremia or meningitis caused by a strain of ST-17 clone of GBS strain. A polypeptide encoded by a polynucleotide selected from the following group:
a) A group B streptococcal gene encoding the surface protein Gbs2018 of the strain of the ST-17 clone, comprising a nucleic acid sequence having the sequence S10 of SEQ ID NO: 5, and at least one SEQ ID NO: 13 A gene comprising a domain consisting of at least one nucleic acid sequence having the sequence S11a and / or the sequence S11b of SEQ ID NO: 15;
b) a polynucleotide that hybridizes with the gene of a) under stringent conditions;
c) a fragment derived from the group B streptococcus gene of a) or a corresponding fragment derived from a polynucleotide that hybridizes with the gene defined in a) under stringent conditions, the GBS strain of ST-17 clone A fragment encoding a polypeptide that is suitable for use in a method for the specific detection of or comprising an epitope of said Gbs2018 surface protein;
d) a polynucleotide substantially complementary to a fragment of the gene defined in a) or of the polynucleotide defined in b) or of the fragment defined in c), which is specific for the GBS strain of the ST-17 clone A polynucleotide encoding a polypeptide suitable for use in a method for complete detection or comprising an epitope of said surface protein Gbs2018;
e) However, the polynucleotide is not a gene having the coding sequence of SEQ ID NO: 1. 32. The polypeptide of claim 31, which is a fragment having at least 6 amino acid residues and comprising an epitope of the surface protein Gbs2018 of a strain of ST-17 clone. 33. The polypeptide of claim 32, wherein the surface protein has the sequence of SEQ ID NO: 2. 34. The polypeptide of any one of claims 31 to 33, wherein the polypeptide is derived from a polypeptide region designated S10 of Gbs2018 protein of GBS strain of ST-17 clone, A polypeptide selected from:
A polypeptide S10 segment;
Its fragments;
A polypeptide comprising said segment and having at least 190 amino acid residues and having less than 550 or less than 300 or less than 250 amino acid residues. 34. The polypeptide according to any one of claims 31 to 33, wherein the polypeptide is derived from a polypeptide region designated S11 of Gbs2018 protein of GBS strain of ST-17 clone, wherein: A polypeptide selected from:
The polypeptide S11a segment;
A polypeptide S11b segment;
Its fragments;
A polypeptide comprising said segment S11a and having at least 72 amino acid residues and having less than 550 or less than 300 or less than 250 amino acid residues, comprising said segment S11b and comprising at least 79 amino acid residues A polypeptide having and having less than 550 or less than 300 or less than 250 amino acid residues. 35. The polypeptide of claim 34, wherein the polypeptide is a fragment of the S10 polypeptide region having SEQ ID NO: 6, which is recognized by an antibody against the Gbs2018 surface protein of the ST-17 clone. 36. The polypeptide of claim 35, wherein the polypeptide is a fragment of the S11 polypeptide region having SEQ ID NO: 14 or SEQ ID NO: 16 recognized by an antibody against the Gbs2018 surface protein of the ST-17 clone. An epitope, selected from the polypeptide of any one of claims 31-37, comprising 6-50, or 6-30, or 6-15 amino acids, of an ST-17 clone Gbs2018 A polypeptide having the ability to be recognized by antibodies to surface proteins. 39. The polypeptide of claim 38, which is of a strain of ST-17 clone and is not recognized by other strains of GBS serotype III. 40. A recombinant or chimeric polypeptide comprising the polypeptide of any one of claims 31 to 39 and a heterologous polypeptide. 41. A polypeptide according to any one of claims 31 to 40 associated with a carrier molecule. An antibody characterized by specifically recognizing the GBS surface protein of clone ST-17 of GBS strain. 43. The antibody of claim 42, wherein the surface protein has the sequence of SEQ ID NO: 2 or a fragment thereof suitable for use in a method for the specific detection of GBS strains of ST-17 clones. 40. A method for preparing an antibody against the polypeptide of any one of claims 31-39, comprising immunizing an animal with the polypeptide, and an antibody produced against the polypeptide. Recovering. 45. A kit for in vitro detection of infection by GBS strain in a biological sample, comprising the polypeptide of any one of claims 31 to 41 or the antibody or fragment thereof of claim 42 to 44, and A kit comprising means for detecting the polypeptide or the antibody or fragment thereof and the antigen / antibody complex obtained from the biological sample. Method for in vitro detection of highly pathogenic GBS strains of ST-17 clones, detecting Gbs2018 surface protein of ST-17 clones or fragments thereof in biological samples or Gbs2018 surface proteins of ST-17 clones Or targeting a fragment thereof. A method according to claim 46, wherein the polypeptide according to claims 31-41 or the antibody according to claim 42 or 43 or a fragment thereof is contacted with the biological sample and antigen / antibody Detecting the formation of the complex. 48. A method according to any one of claims 44, 46 and 47, wherein the biological sample is obtained from a mammal, in particular a human. 49. A method according to any one of claims 44 and 46 to 48, wherein the biological sample is derived from a pregnant woman, an embryo, a fetus, a newborn and / or a child. 50. A method according to any one of claims 44 and 46-49 for use in detecting neonatal invasive infection, wherein the infection is caused by a strain of ST-17 clone of GBS strain. 51. A method according to any one of claims 44 and 46-50 for use in detecting neonatal pneumonia, bacteremia or meningitis caused by a strain of ST-17 clone of GBS strain. A polynucleotide according to any one of claims 1 to 15 for use in the detection of neonatal invasive infections, neonatal mortality or neonatal morbidity caused by strains of the ST-17 clone of GBS strain or claim Item 20. The kit according to any one of Items 17 to 19. The polynucleotide of any one of claims 1 to 16 or the use of claims 17 to 19 for use in the detection of pneumonia, bacteremia or meningitis in a newborn caused by a strain of clone ST-17 of GBS strain The kit according to any one of the above. 20. A polynucleotide according to any one of claims 1 to 16 or a polynucleotide according to any one of claims 17 to 19 for use in the detection of strains of ST-17 clones of GBS strains in mammals and / or humans. Kit. The polynucleotide of any one of claims 1 to 16 or the use of claims 17 to 19 for use in the detection of strains of ST-17 clones of GBS strains in pregnant women, embryos, fetuses and / or neonates The kit according to any one of the above.

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