The present invention relates to tuberculosis diagnosis; more particularly, relates to using a chip array construction of specific tubercle bacillus (TB) genes and drug-resistance genes for detecting tubercle bacillus and drug resistance.
TB is an old contagious disease. Although it has been long on developing methods for preventing, controlling and curing this disease, TB is still a key issue in the world, which kills greatest number of people among all contagious diseases.
A characteristic of TB is that there may be no sign appeared after a person is infected and only 10% of the patients have morbidity. Most of the patients have the thalli lived in their bodies for a long time before the morbidity appears. Thus, the cause that turns a patient of latent TB into one of active TB may be exogenous reinfection or endogenous reactivation. Hence, for diagnosing TB clinically, clinical expression shown on the patients, changes shown on X-ray films and laboratorial experiments are all required for confirmation.
Regarding laboratorial examination, technologies relating to histopathology, staining of acid-fast bacterium and TB culturing are used. However, they all have their limits. Take staining of acid-fast bacterium as an example. At least 5000 to 10000 bacteria have to be contained in one milli-liter of a specimen. Besides, there exists a high possibility of fake positive for this method. That is because some other bacteria may show positive results too. Regarding TB culturing, although it is the most sensitive diagnosing method, it takes 4 to 8 weeks to obtain the result and is not suitable for clinical use.
As following development of biological technologies, clinical diagnosis of TB has evolutional progress on molecular diagnostic technologies, like polymerase chain reaction (PCR), PCR-Restriction Fragment Length Polymorphism (PCR-RFLP), etc. In the early years, PCR are directly used for detecting molecular marks of TB in patients' specimens, like deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) of heat shock proteins 65 (hsp65) and inserted section 6110 (IS6110). In addition, with coordination of restriction fragment length polymorphism (RFLP), the nucleic-acid molecular typing of the detected thallus is identified. However, expression of specific DNA or messenger ribonucleic acid (mRNA) in a patient's specimen is still not satisfactory clinically.
Through decoding the TB genes, it is found that genomic deletion is existed between TB and mycobacterium bovis BCG, where lost sections are called regions-of-difference (RD). The causes for these RDs may be errors on duplicating DNAs of the genes or on inserting sections, including deletion, insertion, inversion, replication, etc.
The RD sections have many important genes and pathogenic factors. These sections may differ between pathogens of TB genes. Hence, the RD sections can be used for identifying the TB genes, which identifies specific genes with high sensitivity.
In 2009, 14 specific target genes were selected as testing targets for constructing a TB gene diagnosis chip. Through using a platform for detecting tiny amount of nucleic acid, multiple gene targets are detected simultaneously, where sensitivity reaches a level for detection with only 5 cells in one milli-liter of blood. Thus, a TB gene detection chip for sputum specimen is constructed.
This chip can detect 85% of TB complex (TBC), where PCR-RFLP is 62.5%. In an experiment, 52 specimens are picked out by the chip from 56 positive-cultured and positive-dyed sputum specimens, where only 39 are picked out through PCR-RFLP. In another experiment, 16 specimens are picked out by the chip from 24 positive-cultured and negative-dyed sputum specimens, where only 11 are picked out through PCR-RFLP.
Accordingly, gene chip detection is easily operated without much human labor and time. Moreover, sensitivity of the gene chip detection is far higher than PCR-RFLP.
In the market, some TB detection sets include Spoligotyping Method (Holland), TB Ag Rapid Test (Taiwan), Amplified MTDR (USA), DR. MTBC Screen Kit (Taiwan) and GenoType MTBDRplus (German). Therein, Spoligotyping Method detects TB oligonucleotide spectrum at first and, then, finds its typing from a database. But, the resolving power is low and drug resistance is not detected. TB Ag Rapid Test uses specific antigen to detect TB directly. But, its cost is high; TB colony has to be cultured; its procedure is complex; it takes time; and, not to mention, drug resistance is not detected. DR. MTBC Screen Kit magnifies specific gene sections through PCR and, then, the chip is processed through hybridization. Although drug-resistance genes against Rifampicin can be found, 100-thousand TB bacteria in one milli-liter of sputum are required for valid detection with a 65% sensitivity only. GenoType MTBDRplus magnifies TB drug-resistance genes through PCR and, then, hybridization is processed with probes. Although drug-resistance genes in TB against Ofloxacin, Streptomycin and Ethambutol can be found, its cost is high; its technology is complex; it takes time for detection; and it only tests efficacy but not TB itself.
Furthermore, a prior art of detection chip directly detected active TB in a sputum specimen. Yet, it detects Tb only and do not analyzes efficacy on gene cluster. Hence, the prior arts do not fulfill all users' requests on actual use.
The main purpose of the present invention is to use a construction of specific TB genes and drug-resistance genes for detecting TB and testing drug resistance simultaneously.
To achieve the above purpose, the present invention is a method of fast tuberculosis diagnosis and efficacy test, comprising steps of: (a) obtaining a sputum specimen and extracting messenger ribonucleic acids (mRNAs) in the sputum specimen to synthesize a required amount of complementary deoxyribonucleic acids (cDNAs) through reverse transcription; (b) labeling the cDNAs with Biotin to obtain a plurality of bioprobes; (c) synthesizing TB genes and drug-resistance genes in vitro into a specific gene cluster of TB and a drug-resistance gene cluster and obtaining a chip array construction through crosslinking by dotting the specific gene cluster of TB, the drug-resistance gene cluster, positive controls, negative controls and blank controls into array on a nylon membrane, where the specific gene cluster of TB is specified through a specific oligonucleotide design; and where the chip array construction is formed into a plurality of gene-testing points on the nylon membrane; (d) hybridizing the gene-testing points of the chip array construction with biomolecules of the bioprobes and washing out un-hybridized bioprobes; and (e) blocking the bioprobes obtained after hybridization of the chip array construction to form crosslinks with Streptavidin-HRP accompanied with a washing process afterwards and, then, adding a coloring agent of diaminobenzidine (DAB) to process color development for analyzing and interpreting an image thus obtained. Accordingly, a novel method of fast tuberculosis diagnosis and efficacy test is obtained.
The present invention will be better understood from the following detailed description of the preferred embodiment according to the present invention, taken in conjunction with the accompanying drawings, in which
The following description of the preferred embodiment is provided to understand the features and the structures of the present invention.
Please refer to
(a) DNA extraction 11: A sputum specimen of a patient is collected and messenger ribonucleic acids (mRNAs) in the sputum specimen is extracted for synthesizing a required amount of complementary deoxyribonucleic acids (cDNAs) through reverse transcription.
(b) Multiple linear amplification and labeling 12: The cDNAs are labeled with Biotin to form a plurality of bioprobes.
(c) Fabrication of chip array construction 13: Tubercle bacillus (TB) genes along with drug-resistance genes are synthesized in vitro into a specific gene cluster of TB along with a drug-resistance gene cluster, where the specific gene cluster of TB is specified through a specific oligonucleotide design. Then, a chip array construction is formed through crosslinking by dotting the specific gene cluster of TB, the drug-resistance gene cluster, positive controls, negative controls and blank controls into array on a nylon membrane. Therein, the specific gene cluster of TB comprises 13 specific TB genes; the drug-resistance gene cluster comprises 6 drug-resistance genes; and the chip array construction is formed into a plurality of gene-testing points on the nylon membrane.
(d) Hybridization 14: The bioprobes are hybridized with the chip array construction, where the gene-testing points of the chip array construction are hybridized with biomolecules of the labeled bioprobes. Then, un-hybridized bioprobes are washed out.
(e) Color development 15: After hybridization with the chip array construction, the bioprobes are blocked to form crosslinks with Streptavidin-HRP accompanied with a washing process afterwards. Then, a coloring agent of diaminobenzidine (DAB) is added for color development to analyze and interpret an image thus obtained.
As shown in Table 1, the specific gene cluster of TB comprises specific oligonucleotide sequences selected from the specific TB genes. These 13 specific TB genes comprises hsp65, Rv0577, Rv3120, Rv2073c, Rv1970, Rv3875, Rv3347c, Rv1510, Rv0186, Rv0124, TbD1, mtp40 and mpb83, which are obtained through analysis by Primer Premier 5.0 (PREMIER Biosoft International, Palo Alto, Calif.).
As shown in Table 2, the drug-resistance gene cluster for testing anti-tuberculosis drugs comprises 6 oligonucleotide sequences, which comprises katG, rpoB, gyrA, embB, rpsL and rrs.
Please refer to
The testing area of bacillus tuberculosis 21 comprises a plurality of gene-testing points 2a for separately conjugating a specific gene cluster of TB with specific bioprobes to be reacted with specific biomolecules of the specific bioprobes for color development. This specific gene cluster of TB comprises 13 specific TB genes, which are hsp65, Rv0577, Rv3120, Rv2073c, Rv1970, Rv3875, Rv3347c, Rv1510, Rv0186, Rv0124, TbD1, mtp40 and mpb83.
The testing area of drug resistance 22 has a plurality of gene-testing points conjugated with a drug-resistance gene cluster to be reacted with anti-tuberculosis drugs of Isoniazid, Rifampicin, Ofloxacin, Ethambutol and Streptomycin for color development. The conjugated drug-resistance gene cluster comprises 6 drug-resistance genes, which are katG, rpoB, gyrA, embB, rpsL and rrs.
The above gene-testing points 2a.2b are arranged into array.
Please refer to
Mycobacterium
M. canettii
M. tuberculosis
M. africamun(lb)
M. africamun(lib)
M. microti
M. caprie
M. bovis
M. bovis BCG
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To sum up, the present invention is a method of fast tuberculosis diagnosis and efficacy test, where specific TB genes and drug-resistance genes are used as probes to test TB and drug resistance simultaneously through analysis after hybridization; and, thus, the present invention is a fast method with low cost for detecting TB and testing drug resistance simultaneously.
Number | Date | Country | Kind |
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101217741 | Sep 2012 | TW | national |