This invention relates to a PCR-based prototype kit for detecting chlamydia trachomatis and Neisseria gonorrhoeae.
In India Chlamydia trachomatis and Neisseria gonorrhoeae, are detected by separate method in spite of the fact about 50% of the sample are co-infected. The usual method of detection is Gram-staining followed by confirmation like, antigen detection or biochemical assay. Both these methods are highly unsatisfactory, especially in asymptomatic patient (where the infection load is low). At present in India few private pathological laboratory are carrying out PCR based diagnostic, for which they are completely dependent on the import of kit. There is no indigenous diagnostic kit available for Chlamydia trachomatis and Neisseria gonorrhoeae at present.
The drawbacks of the term existing state of art is as follows:
Culture method: Sensitivity of this method is as low as 50% as organisms may lose infectivity during transportation and storage, which will reduce the likelihood of propagation. In addition, the surface area of the cell culture layer and/or the amount of sample material added to the cell culture influence the sensitivity. Cell culture, however, is time-consuming, laborious and expensive and can therefore be provided by only a few central laboratories.
Antigen Detection: The diagnostic efficacy of these methods is not high enough to warrant clinical use unless the need for a fast result overweighs the lower diagnostic accuracy. Also, the ELISA tests may reveal positive results in the presence of other organisms such as E. coli and Bacteroides sp, and Staphylococcus aureus may be captured instead of Chlamydia due to binding to the Fc region of the antibodies, thereby causing false-positive reactions. DFA requires skilled personnel in order to differentiate C. trachomatis organisms from non-specific fluorescent particles.
DNA/RNA Detection: The diagnostic performance of non-amplified probe technique is not substantially different from that of the best ELISA.
Nucleic acid amplification tests (NAATs): Target gene for NAATs The Plasmid: Some studies give evidence or suggest that the plasmid-free variants are present in clinical samples, and although it may seem that plasmid is involved in DNA replication, it has been possible to culture a plasmid-free variant. Thus, the infections caused by plasmid-free variants will be undetected if the plasmid is used as target gene.
The 16S-rRNA gene: Due to high homology of the 16S rRNA gene with other organisms, optimal reaction conditions are crucial in order to avoid annealing of primers to 16S-rRNA genes of the other organisms that are present in all non-sterile clinical samples.
An object of this invention is to propose a PCR-based prototype kit for detecting Chlamydia trachomatis and Neisseria gonorrhoeae simultaneously and individually.
Another object of this invention is to propose a kit which is cost effective.
Further object of this invention is to propose a kit which reduces the chances of error and any cross contamination.
Still further object of this invention is to propose a kit which can be operated without any technical expertise.
According to this invention there is provided a PCR based prototype kit for detecting Chlamydia trachomatis and Neisseria gonorrhoeae comprising;
A transport medium for sample collection solution A & B, a reaction mixture having the primers for Chlamydia trachomatis & Neisseria gonorrhoeae, a gel loading dye, Agarose gel, gel running buffer and a DNA marker ladder.
In the present invention a multiplex PCR based prototype kit for the detection of the Chlamydia trachomatis and Neisseria gonorrhoeae, based on designed primers (patent in process). The kit contains all the reagents for collection of clinical samples, for carrying out amplification by PCR and the detection of the product, as well as the protocol to be used for diagnosis of Chlamydia trachomatis and Neisseria gonorrhoeae in patient samples. Furthermore, three kits have been developed:
Kit for diagnosis of samples infected with Chlamydia trachomatis with an internal control.
Kit for diagnosis of sample infected with Chlamydia trachomatis without internal control.
Kit for detection of Chlamydia trachomatis and Neisseria gonorrhoeae simultaneously.
In one embodiment, the invention is directed to primers for diagnosing of sample infected with Chlamydia trachomatis with an internal control comprising primers SEQ ID No.1 and 2 or 3 and 4 with 9 and 10 or 11 and 12 and Primers for diagnosis of sample infected with Chlamydia trachomatis without internal control comprising primers SEQ ID No.1 and 2 or 3 and 4.
In another embodiment, the invention is directed to primers for detection of Chlamydia trachomatis and Neisseria gonorrhoeae simultaneously with internal control comprising primers SEQ ID No.1 and 2 or 3 and 4 for Chlamydia trachomatis, SEQ ID No.5 and 6 or 7 and 8 for Neisseria gonorrhoeae, with 9 and 10 or 11 and 12.
In principle any pair of oligonucleotide which bind to the two strand of duplex DNA in sufficiently close proximity could be used as primers for PCR but in practice no guarantee of success in selecting suitable primer set for PCR. However, it is known that many theoretically suitable primer sets simply do not work in practice for co-amplification.
The primer sets identified have established that they are specific and complimentary to the target nucleic acid to form a desired hybridization products and then be extendable by DNA polymerase in practice under routine use.
However, inventors are using exactly complimentary primer sets to the target site of genomic DNA sequences of Neisseria gonorrhoeae and Chlamydia trachomatis for designing a diagnostic method using crude samples while cryptic plasmid is being used in most of the existing methods.
So the novelty of the method is the identification of unique, specific, sensitive yet cost effective PCR based detection of Gonococcal and Chlamydial infection.
The indicated length of orf1 and phospholipase D endonuclease is the size of amplicon obtained from said genes for the detection of Neisseria gonorrhoeae and Chlamydia trachomatis. The Primer region of genes have been chosen in non variable which is present in most of the species of Neisseria gonorrhoea and Chlamydia trachomatis infecting human.
The 10% of positive samples were confirmed by sequencing and sequences were showed 100% homology to existing sequence of orf1 gene of Neisseria gonorrhoeae and phospholopase D endonuclease gene of Chlamydia trachomatis.
Primers sequences of Phospholipase D Endonuclease Superfamily gene, used in diagnosis of Chlamydia trachomatis generates 368-bp product.
Amplified region of gene used in diagnosis
Primers sequences of Orfl gene used in diagnosis of Neisseria gonorrhoeae, generates 250-by product.
Amplified region of gene used in diagnosis
The amplified region is 368 bp. When amplified in a sample, the sample is positive for Chlamydia trachomatis
Internal Control
Primers sequences used in prototype kit as a internal control.
General information:
I. Information for SEQ ID NO: 1:
Sequence Characteristics
(A) LENGTH: 28 base pairs
(B) TYPE: nucleic acid
(C) STRANDEDNESS: single
(D) TOPOLOGY: linear
(E) SEQUENCE DESCRIPTION: SEQ ID NO: 1: 5′-AACCCACTTCTTCCACAGTTTCTTCT AA-3′
2. Information for SEQ ID NO: 2:
Sequence Characteristics
(A) LENGTH: 22 base pairs
(B) TYPE: nucleic acid
(C) STRANDEDNESS: single
(D) TOPOLOGY: linear
(E) SEQUENCE DESCRIPTION: SEQ ID NO: 2: 5′-TGGCATCGCATAGCATTCTTTG-3′
3. Information for SEQ ID NO:3:
Sequence Characteristics
(A) LENGTH: 26 base pairs
(B) TYPE: nucleic acid
(C) STRANDEDNESS: single
(D) TOPOLOGY: linear
(E) SEQUENCE DESCRIPTION: SEQ ID NO:3: 5′-TCTTTTTAAACCTCCGGAACCCACTT-3′
4. Information for SEQ ID NO: 4:
Sequence Characteristics
(A) LENGTH: 25 base pairs
(B) TYPE: nucleic acid
(C) STRANDEDNESS: single
(D) TOPOLOGY: linear
(E) SEQUENCE DESCRIPTION: SEQ ID NO:4: 5′-GGATGGCATCGCATAGCATTCTTTG-3′
5. Information for SEQ ID NO: 5:
Sequence Characteristics
(A) LENGTH: 21 base pairs
(B) TYPE: nucleic acid
(C) STRANDEDNESS: single
(D) TOPOLOGY: linear
(E) SEQUENCE DESCRIPTION: SEQ ID NO:5: 5′ GA TCCAACTATTCCCGATTGC-3′
6. Information for SEQ ID NO: 6:
Sequence Characteristics
(A) LENGTH: 24 base pairs
(B) TYPE: nucleic acid
(C) STRANDEDNESS: single
(0) TOPOLOGY: linear
(E) SEQUENCE DESCRIPTION: SEQ ID NO:6: 5′-GCAAAGTT ATACAGCTTCGCCTGA-3′
7. Information for SEQ ID NO: 7:
Sequence Characteristics
(A) LENGTH: 20 base pairs
(B) TYPE: nucleic acid
(C) STRANDEDNESS: single
(D) TOPOLOGY: linear
(E) SEQUENCE DESCRIPTION:SEQ ID NO:7: 5′-CCTGATGCTAGGGACGGATT-3′
8. Information for SEQ ID NO: 8:
Sequence Characteristics
(A) LENGTH: 22 base pairs
(B) TYPE: nucleic acid
(C) STRANDEDNESS: single
(D) TOPOLOGY: linear
(E) SEQUENCE DESCRIPTION: SEQ ID NO:8: 5′-CCCTAAATTATGCGGTGGAAT-3′
9. Information for SEQ ID NO: 9:
Sequence Characteristics
(A) LENGTH: 17 base pairs
(B) TYPE: nucleic acid
(C) STRANDEDNESS: single
(D) TOPOLOGY: linear
(E) SEQUENCE DESCRIPTION:SEQ ID NO:9: 5′-CGTACCAGAAGGAGCAG-3′
10. Information for SEQ ID NO: 10:
Sequence Characteristics
(A) LENGTH: 18 base pairs
(B) TYPE: nucleic acid
(C) STRANDEDNESS: single
(D) TOPOLOGY: linear
(E) SEQUENCE DESCRIPTION:SEQ ID NO:10: 5′-CGTCTCCAGGACAACGTC-3′
11. Information for SEQ ID NO:11:
Sequence Characteristics
(A) LENGTH: 17 base pairs
(B) TYPE: nucleic acid
(C) STRANDEDNESS: single
(D) TOPOLOGY: linear
(E) SEQUENCE DESCRIPTION: SEQ ID NO:11: 5′-TGCTCTCAGAGTTTGGACAGTTCCT-3′
12. Information for SEQ ID NO:12:
Sequence Characteristics
(A) LENGTH: 20 base pairs
(B) TYPE: nucleic acid
(C) STRANDEDNESS: single
(D) TOPOLOGY: linear
(E) SEQUENCE DESCRIPTION: SEQ ID NO:12: 5′-TTTCTTGGCGGGTGCAGACA-3′
This present invention has been explained in greater detail in the examples:
Kit with internal control.
Protocol 1
Sample Collection:
Sample is collected as a swab and is dipped in the vial containing sterile 1 ml Transport medium and stored at 4° C. for several hours or freezer for a maximum time up to one week.
Preparation of Sample DNA:
Setting up the PCR:
PCR program:
After completing the PCR reaction, add 10 μl of the loading dye. Fractionate the product on the agarose gel (1.5%), by loading 25-30 μl the sample per well as described below.
Preparation of Agarose Gel:
Protocol:
Result Analysis:
Alternate protocol for sample preparation from clinical samples.
Protocol 2
Preparation of Sample DNA:
All other steps will be as mentioned in the detailed assay.
Components Supplied in the Kit One:
Annexure:2
Prototype kit two for diagnosis of Chlamydia Trachomatis
Kit II Without Internal Control
Protocol 1
Sample Collection:
Sample is collected as a swab and is dipped in the vial containing sterile 1 ml Transport medium and stored at 4° C. for several hours or in freezer for a (maximum time up to one week).
Preparation of Sample DNA:
Setting up the PCR:
PCR program:
After completing the PCR reaction, add 10 μl of the loading dye. Fractionate the product on the agarose gel (1.5%), by loading 25-30 μl the sample per well as described below.
Protocol:
Result Analysis:
Only Chlamydia trachomatis positive sample give a band of 368 by as is evident from the DNA size marker lane.
Components Supplied in the Kit:
Alternate protocol for sample preparation from clinical samples.
Protocol 2
Preparation of Sample DNA:
All other protocols will be as mentioned in the detailed assay.
Annexure: 3
Prototype Kit III
For diagnosis of Chlamydia Trachomatis and Neisseria Gonorrhoeae Kit III with internal control.
Protocol
Sample Collection:
Sample is collected as a swab and is dipped in the vial containing sterile 1 ml Transport medium and stored at 4° C. for several hours or in freezer for a (maximum time up to one week).
Preparation of Sample DNA:
Setting up the PCR:
PCR program:
After completing the PCR reaction, add 10 μl of the loading dye. Fractionate the product on the agarose gel (1.5%), by loading 25-30 μl the sample per well as described below.
Protocol:
Result Analysis:
Components Supplied in the Kit:
Number | Date | Country | Kind |
---|---|---|---|
3437/DEL/05 | Dec 2005 | IN | national |
Number | Date | Country | |
---|---|---|---|
Parent | 11436063 | May 2006 | US |
Child | 12651819 | US |