JP2004141167A - Diagnostic probe for infectious disease caused by streptococcus pyogenes microbe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a probe originating from pathogen specifically detecting Streptococcus pyogenes microbe, which is a pathogen of an infectious disease, capable of rapidly identifying bacterial strains and to provide a base sequence for guidance of preparation of a PCR primer amplifying the DNA originating from the pathogen of an infectious disease, or as a standard sequence appropriate for comparison and referring a Genomic DNA contained in a clinical specimen material. <P>SOLUTION: The probe containing the fragment of DNA of the specific sequence substantially contained in the Streptococcus pyogenes microbe is provided by extracting the DNA from the Streptococcus pyogenes microbe, completely digesting by a restriction enzyme Hind III and cloning to a proper vector. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a probe useful for the detection and identification of Streptococcus pyogenes bacteria, which are causative bacteria of infectious diseases, in particular, pharyngitis, rheumatic fever, nephritis, erysipelas, scarlet fever, and sepsis.

  Diseases caused by infection with pathogenic microorganisms are collectively called infectious diseases. Pathologically, infection means that pathogenic microorganisms (hereinafter referred to as "fungi") invade the living body and establish a foothold for growth. In this regard, the onset caused by bacterial growth in a living body depends on the correlation between host resistance and bacterial virulence.

Streptococcus is a facultative or obligately anaerobic gram-positive cocci arranged in a chain. It is divided into three types of α, β, and γ according to the properties of the hemolytic ring around the colony that has grown on the blood agar medium, and further ranges from A to V depending on the antigenicity (Lancefield's classification) of the C polysaccharide possessed by the cells. (Excluding I and J).

Streptococcus pyogenes bacteria show β-type hemolysis (complete hemolysis), is a type of streptococci belonging to group A in the Lancefield classification, and is human pharyngitis, tonsillitis, scarlet fever, erysipelas, puerperium It is clinically important as a causative bacterium such as fever and sepsis. It is also known that after infection, secondary occurrences of rheumatic fever and nephritis, which are allergic diseases called poststreptococcal diseases. Furthermore, in recent years, cases of severe septic shock accompanied by myositis due to infection with Streptococcus pyogenes bacteria have been reported (fulminant group A streptococcal infection).

咽 Pharyngitis due to Streptococcus pyogenes is often accompanied by marked pharyngeal redness and swelling of the cervical lymph nodes, and pharyngeal pain is frequently reported. Therefore, it is possible to suspect this disease from clinical symptoms. However, they may not always show clear clinical symptoms, and it is necessary to give optimal chemotherapy to prevent the occurrence of complications, and it is desirable to avoid unnecessary administration of antibacterial agents. Bacteriological rapid diagnosis is needed.

In addition, it has been reported that fulminant group A streptococcal infection is associated with severe necrotizing fasciitis in more than 50% of cases, and rapidly progresses to multiple organ failure, which may turn the point of death. Not a few.

In general, Streptococcus pyogenes bacteria are known to exhibit high sensitivity to β-lactam drugs such as ampicillin and cefaclor, but about 30% of highly resistant strains exist for erythromycin and resistant strains also appear for ofloxacin Some caution is required when using macrolides or new quinolones, as some have reported that they do.

As mentioned above, it is important to carry out an accurate early diagnosis of infectious diseases derived from Streptococcus pyogenes and select the most appropriate antibacterial agent.

In ordinary biological techniques, (1) examination of clinical symptoms, (2) cultivation of specimens, and (3) separation and identification of Streptococcus pyogenes from cultures are essential, and these items have been confirmed. Only then can the treatment policy be determined.

For the identification of Streptococcus pyogenes bacteria, samples are usually smear-cultured directly on a blood agar plate medium supplemented with 5% of defibrinated blood such as sheep and horses, and the properties of the hemolytic ring around the colonies grown on the medium are observed. I do.

However, in practice, it is usually difficult to determine the causative organism. That is, the shape of the colony greatly varies depending on the culture conditions, and it is often difficult to specify the colony. In addition, the cultivation of the bacterium has a long time, and furthermore, cultivation for 3 to 4 days is required before obtaining the results of the drug susceptibility results, and rapid diagnosis is impossible. In addition, if a large amount of antibiotics is administered at the time of suspected infection, bacterial enrichment and growth may be suppressed even if the specimen contains bacteria. Thus, the possibility of culturing bacteria from these specimens is extremely low.

  In addition, subroutine methods include instrumental analysis of cell components and metabolites of bacteria (Non-Patent Document 1), methods using specific antibodies (Patent Document 1), and methods using DNA specificity. Although there is a method by hybridization (Patent Document 2) and the like, in each case, isolation and enrichment culture of bacteria are essential.

On the other hand, as a method focusing on the function of phagocytes in infectious diseases, there is a method of examining a smear-stained sample of a buffy coat in which leukocyte components in a blood sample are concentrated. In general, the frequency of bacteria detected in buffy coat specimens is only about 30% in adult bacteremia, similar to the frequency of earlobe blood, but in neonates, bacteria are detected in 7 out of 10 cases (70%). Information on the presence or absence of bacteria in peripheral blood by microscopic examination of smears has been a great guideline in treatment.
JP-A-60-224068 Japanese Patent Publication No. 61-502376 Yoshimi Benno, "Rapid identification of bacteria by gas chromatography", Clinical Laboratory, vol.29, No.12, pp.1618-1623, November 1985, Medical Shoin

  In the prior art, as the pretreatment operation, at least 1-2 days for selective separation of bacteria from the specimen, 1 day for enrichment, 1 day or more for the fixing operation, a total of 3 to 4 days, it takes enough, In reality, this culture is continued until the bacteria grow, so it often takes one week or more for the pretreatment operation, and furthermore, when bacteria other than the causative bacteria of the disease cannot be distinguished when the bacteria are cultured. There is also.

  It is important to note that many bacteria in the specimen to be cultured are taken up by phagocytes and are dead or quiescent due to administration of antibiotics. The actual detection rate of bacteria by culturing using clinical specimens is very low, around 10%. In other words, even if blood from patients clinically suspected of having a possible Streptococcus pyogenes infection is further cultured for more than a day and night, 90% of the blood remains undetectable even after the fact. .

  Under these circumstances, despite the current need to determine the causative organism and the selection of antibiotics in line with that, the clinical diagnosis of Streptococcus pyogenes infection was suspected, Treatment without waiting for the results to be obtained, that is, without knowing the causative organism, administering an effective antibiotic to the most widespread type of bacteria. It relies on a trial-and-error method of switching to a substance.

  Therefore, recently, immunology of Streptococcus pyogenes using methods such as 1) latex agglutination method, 2) coagulation method, 3) enzyme immunoassay method, 4) gold particle measurement method, and 5) liposome immunoassay method. A rapid diagnostic method has been developed for the purpose of detection. In each of these methods, a C-polysaccharide on the surface of Streptococcus pyogenes cells is extracted using nitrous acid or an enzyme, and this is detected as an antigen.

However, the above-described immunological test method has problems such that the measurement results do not match the results obtained by the culture method, that is, false positives and false negatives may be exhibited, and the procedure is complicated.

Furthermore, the characteristics of the diagnostic method utilizing an antigen-antibody reaction, A group antigen possessed bacteria other than S. pyogenes bacteria (e.g., Streptococcus Anjinosasu (Streptococcus Anginosus) such as cells) also will be detected, the species specificity There is a disadvantage that it is inferior.

On the other hand, diagnostic criteria have also been proposed for clinical diagnosis of fulminant group A streptococcal infection (JAMA, vol. 269, pp. 390-391, 1993), but are not suitable for early diagnosis. .

Thus, despite the fact that Streptococcus pyogenes infection is a disease that requires quick and reliable diagnosis, the current situation is that conventional diagnostic methods have not been able to adequately cope with it.

  The present invention has been completed in view of the above-mentioned problems in the technical field, and the gist of the present invention is to specifically specify DNA or RNA possessed by infectious disease-causing bacteria, particularly Streptococcus pyogenes bacteria. An object of the present invention is to elucidate a probe having a high reactivity and a base sequence of a gene portion essentially contained in Streptococcus pyogenes contained in the probe.

  That is, with the probe of the present invention, for example, the DNA of a bacterium that is still maintained in a bacterium that is being taken up and destroyed by phagocytes can be significantly detected based on its specificity using a hybridization method. Thereby, the causative bacteria of the infectious disease can be quickly and reliably detected without culturing and growing the bacteria. In addition, if primers are designed with reference to the nucleotide sequence information of these probes, the causative bacteria of the infectious disease can be identified by amplification of the DNA by PCR without hybridization.

  In addition, if a probe used for hybridization is non-radioactive, for example, if a biotinylated probe is used, it can be detected using an optical microscope even in a general laboratory without a facility using radioisotopes, and the detection operation can be performed quickly and easily. .

  By using the probe of the present invention, for example, an infectious disease-causing bacterium incorporated into a phagocyte can be directly detected without multiplication by a hybridization method, and the bacterium can be quickly and accurately identified. That is, in the diagnosis using the probe of the present invention, bacteria can be identified in one sample, and the time required for diagnosis is about 3 to 4 days (the detection rate is low) of the conventional method, and about 1 to 2 days. The detection rate is extremely high.

Therefore, it not only provides a groundbreaking guideline for the treatment of Streptococcus pyogenes infections, but also allows effective and early treatment of infectious patients, and is expected to reduce mortality.

  In addition, among the infectious disease-causing bacteria, it was made possible to artificially prepare these probes by elucidating the nucleotide sequence of the probe that specifically reacts with the DNA possessed by Streptococcus pyogenes. . Furthermore, the DNA of the causative bacteria of the infectious disease contained in the clinical specimen is amplified by the PCR method using the primers prepared by using a part of the information of the analyzed nucleotide sequence, which is useful for prompt diagnosis of the causative bacteria. be able to.

  Furthermore, by comparing and comparing the nucleotide sequence of the genomic DNA contained in the clinical specimen with the nucleotide sequence analyzed according to the present invention, the infectious disease-causing bacterial species can be rapidly identified.

  Examples of probes derived from Streptococcus pyogenes, which is an infectious disease-causing bacterium, are described below.

Streptococcus pyogenes-derived DNA probe (1) Preparation of Streptococcus pyogenes-derived DNA probeClinical strain Streptococcus pyogenes was cultured overnight in a BHI (Brain Heart Infusion) medium, the cultured cells were collected, and a lysis step was performed. Genomic DNA was prepared according to a modified Saito-Miura method ("Preparation of transforming deoxyribonucleic acid by phenol treatment", Biochem. Biophys. Acta vol. 72 , pp.619-629 (1963)) to which N-Acetylmuramidase SG was added. Extracted.

The extracted DNA was completely digested with the restriction enzyme Hind III, randomly cloned into the vector pGEM-3Z, and obtained from the clone, specific to Streptococcus pyogenes bacteria, that is, specific to DNA possessed by natural Streptococcus pyogenes bacteria. Six types of probes containing DNA fragments showing reactivity were selected.

Then, each selected probe was used as a probe SP-6-28, a probe SP-7-44, a probe SP-14-1, a probe SP-26-36, a probe SP-26-46, and a probe SP-55-3. It was named.

(2) Examination of species specificity of Streptococcus pyogenes-derived DNA probe The reactivity between each probe and DNA of various infectious disease causing strains was examined by the following method.

First, clinical isolates and deposited strains listed in Table 1 below were prepared as target strains. As sources of human genomic DNA and control samples in Table 1, leukocytes collected from four healthy adult males and Escherichia coli K-12, JM109 transformants containing plasmid pGEM-3Z were used. Prepared each.

そして、各臨床菌株を実施例１(1) に記載の方法に従って、各菌株が保有するＤＮＡを抽出し、この抽出したＤＮＡの一定量（例えば、10〜100 ng）をナイロンフィルターにスポットし、アルカリ変性したものをドット・ブロット・ハイブリダイゼーションの試料とした。なお、ヒト・ゲノミックＤＮＡ試料は、前出のSaito-Miura変法に、先に入手した白血球を適用することで調製した。一方、対照試料は、後述する実施例２(1) に記載のプラスミドＤＮＡの調製方法に、先に入手したプラスミド pGEM-3Zを含んだEscherichia coli K-12, JM109 形質転換体を適用することで調製した。次いで、Digoxigenin-11-dUTP (BRL社製) でラベルしたストレプトコッカス・ピオゲネス菌由来のＤＮＡプローブで、マニアティスのマニュアル（T. Maniatis,et al., "Molecular Cloning (A Laboratory Manual Second Edition)", Cold Spring Harbour Laboratory (1989))に従い、45％ホルムアミド、５×SSC、42℃の条件下で、終夜ハイブリダイゼーションを実施した。

According to the method described in Example 1 (1), each clinical strain was subjected to extraction of the DNA contained in each strain, and a fixed amount (for example, 10 to 100 ng) of the extracted DNA was spotted on a nylon filter. The sample denatured with alkali was used as a sample for dot blot hybridization. The human genomic DNA sample was prepared by applying the previously obtained leukocyte to the Saito-Miura modified method described above. On the other hand, a control sample was prepared by applying the Escherichia coli K-12, JM109 transformant containing the previously obtained plasmid pGEM-3Z to the plasmid DNA preparation method described in Example 2 (1) described below. Prepared. Then, using a DNA probe derived from Streptococcus pyogenes bacterium labeled with Digoxigenin-11-dUTP (manufactured by BRL), a manual of Maniatis (T. Maniatis, et al., "Molecular Cloning (A Laboratory Manual Second Edition)", According to Cold Spring Harbor Laboratory (1989)), hybridization was carried out overnight under the conditions of 45% formamide, 5 × SSC and 42 ° C.

  After overnight hybridization, the sample is washed twice with 0.1X SSC and 0.1% SDS at 55 ° C for 20 minutes according to the manual, and then detected and colored with Anti-Dig-ALP conjugates (BRL). Then, the state of hybridization was confirmed. The results obtained are as shown in FIG. FIG. 1 (a) shows the arrangement of DNA strains spotted on each filter subjected to dot blot hybridization, and FIG. 1 (b) shows the respective probes SP-6-28 and SP-6. The results after hybridization and color development using -7-44, SP-14-1, SP-26-36, SP-26-46 and SP-55-3 are shown.

  The experimental results on the reactivity between each probe and the DNA of each clinical strain are shown in Table 2 below.

上記図１および表２から明らかなように、いずれのプローブもストレプトコッカス・ピオゲネス菌に由来するＤＮＡに対してのみ反応性を示し、ストレプトコッカス属以外の菌種由来のＤＮＡはもちろん、ストレプトコッカス属の他の菌種由来のＤＮＡに対しても反応性（ハイブリッドの形成）が認められず、その種特異性が確認された。

As is clear from FIG. 1 and Table 2, all the probes show reactivity only to DNA derived from Streptococcus pyogenes, and not only DNA derived from species other than Streptococcus, but also other Streptococcus species. No reactivity (hybrid formation) was observed with DNA derived from the bacterial species, and the species specificity was confirmed.

Analysis of Nucleotide Sequence The nucleotide sequences of the DNA probes (6 in total) whose species specificity was confirmed in Example 1 were determined according to the following method.

(1) Preparation of plasmid DNA A transformant of Escherichia coli K-12, JM109 containing the subcloned insert (to be determined for nucleotide sequence) in pGEM-3Z (Promega) was added to 5 ml of Luria-Bactani.
Medium (bacto-tryptone, 10 g / 1 L; bacto-yeast extract, 5 g / 1 L; NaCl, 10 g / 1 L; adjusted to pH 7.0 with 5 N NaOH) and cultured overnight.

The culture was collected by centrifugation (5,000 rpm, 5 min.). Precipitate containing lysozyme (Sigma) at a concentration of 2.5 mg / ml 50 mM glucose / 50 mM Tris-HCl (pH 8.0) / 10 mM
100 μl of the EDTA solution was added and left at room temperature for 5 minutes. A 0.2 M aqueous sodium hydroxide solution containing sodium dodecyl sulfate (Sigma) at a concentration of 1% was added to the obtained suspension and mixed. 150 μl of 5M potassium acetate aqueous solution (pH 4.8) was further added and mixed, followed by cooling on ice for 15 minutes.

Then, the supernatant obtained by centrifugation (15,000 rpm, 15 min.) Was treated with phenol / CHCl ₃ , and twice the amount of ethanol was added to the supernatant, followed by centrifugation (12,000 rpm, 5 min.) To precipitate. Got. This precipitate was dissolved in 100 μl of a 10 mM Tris-HCl (pH 7.5) /0.1 mM EDTA solution, a 10 mg / ml RNaseA (Sigma) solution was added, and the mixture was allowed to stand at room temperature for 15 minutes.

300 μl of 0.1 M aqueous sodium acetate solution (pH 4.8) was added to this preparation, treated with phenol / CHCl ₃ , and ethanol was added to the supernatant to obtain a precipitate. The precipitate was dried and dissolved in 10 μl of distilled water to obtain a DNA sample.

(2) Pretreatment for base sequence determination Pretreatment for base sequence determination was performed using the AutoRead (registered trademark) Sequencing Kit (Pharmacia).

  That is, it was adjusted so that the DNA serving as a template had a concentration of 5 to 10 μg in a 32 μl solution. 32 μl of the template DNA was transferred to a 1.5 ml mini tube (Eppendorf), and 8 μl of a 2 M aqueous sodium hydroxide solution was added thereto and mixed gently. After light centrifugation, the mixture was left at room temperature for 10 minutes.

  7 μl of 3 M sodium acetate (pH 4.8) and 4 μl of distilled water were added, and 120 μl of ethanol was further added and mixed, and the mixture was allowed to stand on ethanol / dry ice for 15 minutes. Then, the precipitated DNA was collected by centrifugation for 15 minutes, and the supernatant was carefully removed. The resulting precipitate was washed with 70% ethanol and centrifuged for 10 minutes. Then, the supernatant was again removed carefully, and the precipitate was dried under reduced pressure.

The precipitate was dissolved in 10 μl of distilled water, and a fluorescent primer [Fluorescent Primer, Universal Primer; 5′-Fluorescein-d [CGACGTTGTAAAACGACGGCCAGT (SEQ ID NO: 7)]-3 ′ (1.6 pmol / μl; 0.42 A ₂₆₀ units) Reverse Primer, 5'-Fluorescein-d [CAGGAAACAGCTATGAC (SEQ ID NO: 8)]-3 '(2.1 pmol / μl; 0.42 A ₂₆₀ unit / ml)] 2 μl (0.42 A ₂₆₀ unit / ml, 4- 6 pmol) and 2 μl of annealing buffer were added and mixed gently.

Then, after light centrifugation, heat treatment was performed at 65 ° C. for 5 minutes, quickly placed under 37 ° C., and kept warm for 10 minutes. After the incubation, the mixture was left at room temperature for 10 minutes or more, and centrifuged lightly.
Then, a sample was prepared by adding 1 μl of the buffer for extension and 3 μl of dimethyl sulfoxide.

Fill A, C, and G and T in four mini tubes, AMIX to each tube (dATP the ddATP, dCTP, obtained by dissolving with c ⁷ dGTP and dTTP), dATP and C Mix (ddCTP, dCTP, c ⁷ obtained by dissolving with dGTP and dTTP), dATP and G Mix (ddGTP, dCTP, those were dissolved with c ⁷ dGTP and dTTP) and T Mix (dATP to ddTTP, dCTP, obtained by dissolving with c ⁷ dGTP and dTTP) the 2.5 μl was dispensed. Each solution was stored on ice until use, and was kept warm at 37 ° C. for 1 minute or more before use.

2 μl of diluted T7 DNA polymerase (Pharmacia; 6-8 units / 2 μl) was added to the DNA sample and mixed thoroughly by pipetting or gentle mixing.
Immediately after mixing, the mixture was dispensed into four solutions, each of which was kept warm at 4.5 μl. A new tip was used for dispensing.

After incubation at 37 ° C. for 5 minutes, 5 μl of the stop solution was added to each reaction solution.
Also in this dispensing, a new chip was used. The mixture was kept at 90 ° C for 2 to 3 minutes and immediately cooled on ice. For electrophoresis, 4 to 6 μl per lane was electrophoresed.

(3) Determination of Nucleotide Sequence The determination of the nucleotide sequence of each of the probes having specificity to the DNA of Streptococcus pyogenes disclosed in Examples 1 and 2 was carried out at a migration temperature of 45 ° C. and a migration time of 6 hours. Was performed using an ALF DNA Sequencer system (Pharmacia). Primers were designed sequentially from the sequences revealed from each upstream and downstream, and the above operation was repeated.

As a result, probe SP-6-28 (SEQ ID NO: 1), probe SP-7-44 (SEQ ID NO: 2), probe SP-14-1 (SEQ ID NO: 3), probe SP-26-36 (sequence Nos. 4), SP-26-46 (SEQ ID NO: 5), and SP-55-3 (SEQ ID NO: 6) were revealed.

  As described above, the present invention not only provides a probe for diagnosing infectious diseases, which was the intended purpose, but also as a guideline for preparing primers for PCR, and for comparison with Genomic DNA contained in clinical samples. It is expected to have excellent utility as a suitable standard sequence, and will also have excellent effects such as providing valuable clues in the future search and development of probes that specifically react with DNA possessed by infectious disease-causing bacteria. Things.

  The nucleotide sequence disclosed in the present application was obtained by randomly cloning Genomic DNA of a clinical isolate, and therefore, the usefulness of the nucleotide sequence of the present invention extends to its complementary strand. It is.

  Further, it is naturally conceivable that the DNA contained in the wild-type strain has a mutated portion. However, as is apparent from the disclosure of the above Examples, the DNA mutated portion is used for hybridization for infectious disease diagnosis. The usefulness of the present invention, such as the specificity of the probe of the present invention or the nucleotide sequence information disclosed in the present application can be used to design primers for PCR for the purpose of rapid diagnosis of infectious disease, etc. It has no effect.

(a) shows the arrangement of DNA strains in each dot-blot / hybridization filter, and (b) shows the results after hybridization using each probe and color development.

Claims (1)

A DNA fragment having the nucleotide sequence of SEQ ID NO: 6 that can be obtained by treating DNA possessed by Streptococcus pyogenes , which is an infectious disease-causing bacterium, with restriction enzyme HindIII, and comprising Streptococcus pyogenes A probe for diagnosing an infectious disease, which specifically hybridizes with a DNA carried by the gene.

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