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Journal of Clinical Microbiology, January 2004, p. 372-377, Vol. 42, No. 1
0095-1137/04/$08.00+0 DOI: 10.1128/JCM.42.1.372-377.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.
PCR-Based Genotyping of Mycobacterium tuberculosis with New GC-Rich Repeated Sequences and IS6110 Inverted Repeats Used as Primers
Roman Kot
owski,
Isdore Chola Shamputa, Nabil Abdullah El Aila, Anna Sajduda, Leen Rigouts, Armand van Deun, and Françoise Portaels*
Mycobacteriology Unit, Prince Leopold Institute of Tropical Medicine, B-2000 Antwerp, Belgium
Received 31 March 2003/
Returned for modification 2 June 2003/
Accepted 27 August 2003

ABSTRACT
In the present study we attempted to develop a PCR-based epidemiological
tool for the differentiation of
Mycobacterium tuberculosis isolates.
Use of the designed primers Mtb1 (5'-CCG-GCG-GGG-CCG-GCG-G)
and Mtb2 (5'-CGG-CGG-CAA-CGG-CGG-C) targeting frequently repeated
16-bp sequences in combination with primers sited at the inverted
repeats flanking IS
6110 allowed differentiation of
M. tuberculosis isolates.

INTRODUCTION
Mycobacterium tuberculosis is the most frequent cause of bacterial
disease in humans. Tuberculosis kills approximately 2 million
people each year, and more than 8 million people suffer from
the disease annually (
16). The burden of
M. tuberculosis infections
is greatest in low-income countries, where recurrent disease
in previously treated persons is most prevalent. DNA fingerprinting
techniques allow differentiating between endogenous reactivation
and reinfection with a new strain in case of recurrence (
4,
14). In the present study we applied new frequently repeated
GC-rich sequences and inverted repeats flanking IS
6110 as primers
in a PCR-based genotyping method of
M. tuberculosis isolates.
The most common 16-bp oligonucleotides were found in whole M. tuberculosis genomes (2, 5) by using Clone Manager (version 7; Scientific and Educational Software) with successive replacement of S characters in the string SSS-SSS-SSS-SSS-SSS-S with C or G letters according to the highest rate of occurrence of direct and inverted repeats. As a result, the Mtb1 (5'-CCG-GCG-GGG-CCG-GCG-G) sequence was found and was subsequently used in pDRAW32 (version 1.0; AcaClone Software) for comparison to the whole genome, with the indication of four possible mismatches. Repeated oligonucleotides were subsequently extended by successive additions of single nucleotides from the 5' and 3' ends until the repeat number was not lower than 30 (9). Independent searching for at least 16-bp repeats in the genome of M. tuberculosis H37Rv by using Reputer (version 2.74-linux.i586; AG Praktische Informatik, Universität Bielefeld [http://www.genomes.de]) confirmed our results (presented in Table 1). Sequence number 6 (5'-CGG-CGG-CAA-CGG-CGG-CA) containing the 16-bp sequence of the Mtb2 oligonucleotide was previously published (12), but to the best of our knowledge its use as a primer for PCR typing of M. tuberculosis in combination with primers designed within IS6110 inverted repeats is reported here for the first time.
Bacterial suspensions were prepared by scraping of three to
four loops from Löwenstein-Jensen slants and suspension
of the bacilli in Tris-EDTA buffer. For DNA extraction from
mycobacteria, a standardized method based on heat inactivation
for 20 min at 85°C, followed by lysis with lysozyme and
sodium dodecyl sulfate-proteinase K, extraction by cetyltrimethylammonium
bromide-NaCl, and chloroform-isoamyl alcohol purification was
used (
15). In a simple PCR for
M. tuberculosis strain differentiation,
selected GC-rich Mtb1 and Mtb2 sequences were separately used
as primers in combination with primers IS1 (5'-CGG-ACT-CAC-CGG-GGC-GGT-TCA)
and IS2 (5'-CGG-ACA-TGC-CGG-GGC-GGT-TCA) designed within inverted
repeats of IS
6110. For the PCR, 3-µl aliquots of
PvuII-digested
genomic DNA was added to a 47-µl PCR mixture containing
25 pmol of each primer, 1 U of AmpliTaq DNA polymerase (Roche
Molecular Systems, Brussels, Belgium), 0.2 mM concentrations
of each deoxyribonucleotide triphosphate, 10 mM Tris-HCl (pH
8.4), 1.65 mM MgCl
2, 50 mM KCl, and 0.1% Triton X-100 and overlaid
with mineral oil. Cycling conditions were as follows: denaturation
at 94°C for 5 min, followed by amplification for 35 cycles
of 94°C for 1 min, 68°C (or 66°C) for 1 min, and
72°C for 1 min, followed by a final extension at 72°C
for 10 min. The annealing temperature at 68°C used in the
PCR for Mtb1 primer is the optimal hybridization temperature
for mycobacteria (
1). For Mtb2 primer, with 14 GC nucleotides,
a lower temperature at 66°C for efficient DNA stringency
is required. A total of 20 µl of amplified DNA was subjected
to electrophoresis through a 2% agarose gel, detected by ethidium
bromide staining, and visualized under UV light.
The principle of the presented PCR genotyping method is depicted in Fig. 1. The selection criteria for the Mtb1 and Mtb2 primers were their high GC content and high copy number in M. tuberculosis and M. bovis (7) genomes (Table 1). The distribution of possible regions for hybridization of Mtb1, Mtb2, and IS6110 sequences in the genomes of M. tuberculosis (H37Rv and CDC1551) is presented in Fig. 2. A Clone Manager version 7-aided comparison analysis showed that the entire Mtb1 and Mtb2 sequences cannot hybridize with the genomes of Corynebacterium efficiens YS-314, Escherichia coli K-12, Staphylococcus epidermidis ATCC 12228, Bacillus anthracis AMES, Clostridium perfringens, Chlamydia pneumoniae J138, Staphylococcus aureus MW2, and Helicobacter pylori J99 (ftp://ftp.ncbi.nih.gov/GenBank/genomes/Bacteria/).
In experimental studies, 27
M. tuberculosis isolates were analyzed.
Ten colonies isolated from one sputum sample were subjected
to spoligotyping (Isogen; Bioscience, Maarssen, The Netherlands)
and IS
6110-restriction fragment length polymorphism (RFLP) assay
(
13). One of the 10 colonies tested (colony 8) showed a small
variation in spoligotyping and IS
6110-RFLP: a deficiency in
spacer 25 in the spoligotype and transposition of one IS
6110 copy from a 1.4-kb
PvuII fragment to a 6.1-kb
PvuII fragment
(Fig.
3). These data suggest the existence of a mixed bacterial
population in the sample tested. By using the primer combination
Mtb1-IS1-IS2 or Mtb2-IS1-IS2, clone 8 could be also differentiated
by our new PCR typing method (Fig.
3). In addition, 13 of 17
M. tuberculosis tested strains showed identical affiliation
into six clusters with our PCR-based genotyping method and IS
6110-RFLP
assay (Fig.
4, lanes 1 to 6 and 14 to 20). The other seven isolates
showed different banding patterns by both methods (Fig.
4, lanes
7 to 13).
The PCR-fingerprinting method presented here can be useful for
laboratories performing
M. tuberculosis epidemiology studies.
The major advantage of this method versus DRE-PCR (
6) is the
high annealing temperature that improves reproducibility of
results. In addition, like the IS
6110-inverse PCR (
10) and ligation-mediated
PCR (
11), this method can be helpful in the localization of
IS
6110 copies throughout the genomes of
M. tuberculosis by sequencing
amplimers, thereby providing more information about possible
"hot spots" for integration of IS
6110 in the genomes of clinical
isolates (
8).

ACKNOWLEDGMENTS
This study was funded by Damien Foundation (Brussels, Belgium).
R.K. was supported by Marie Curie Individual Fellowship under
research grant MCFI-1999-01398.

FOOTNOTES
* Corresponding author. Mailing address: Prince Leopold Institute of Tropical Medicine, Mycobacteriology Unit, Department of Microbiology, Nationalestraat 155, 2000 Antwerp, Belgium. Phone: 32-3-247-63-17. Fax: 32-3-247-63-33. E-mail:
portaels{at}itg.be.

Present address: Faculty of Chemistry, Gdansk University of Technology, 80-952 Gdansk, Poland. 

REFERENCES
1 - Athwal, R. S., S. S. Deo, and T. Imaeda. 1984. Deoxyribonucleic acid relatedness among Mycobacterium leprae, Mycobacterium lepraemurium and selected bacteria by dot blot and spectrophotometric deoxyribonucleic acid hybridization assays. Int. J. Syst. Bacteriol. 34:371-375.[Abstract/Free Full Text]
2 - Cole, S. T., R. Brosch, J. Parkhill, T. Garnier, C. Churcher, D. Harris, S. V. Gordon, K. Eiglmeier, S. Gas, C. E. Barry III, F. Tekaia, K. Badcock, D. Basham, D. Brown, T. Chillingworth, R. Connor, R. Davies, K. Devlin, T. Feltwell, S. Gentles, N. Hamlin, S. Holroyd, T. Hornsby, K. Jagels, B. G. Barrell, et al. 1998. Deciphering the biology of Mycobacterium tuberculosis from the complete genome sequence. Nature 11:537-544.
3 - Cole, S. T., K. Eiglmeier, J. Parkhill, K. D. James, N. R. Thomson, P. R. Wheeler, N. Honore, T. Garnier, C. Churcher, D. Harris, K. Mungall, D. Basham, D. Brown, T. Chillingworth, R. Connor, R. M. Davies, K. Devlin, S. Duthoy, T. Feltwell, A. Fraser, N. Hamlin, S. Holroyd, T. Hornsby, K. Jagels, C. Lacroix, J. Maclean, S. Moule, L. Murphy, K. Oliver, M. A. Quail, M. A. Rajandream, K. M. Rutherford, S. Rutter, K. Seeger, S. Simon, M. Simmonds, J. Skelton, R. Squares, S. Squares, K. Stevens, K. Taylor, S. Whitehead, J. R. Woodward, and B. G. Barrell. 2001. Massive gene decay in the leprosy bacillus. Nature 409:1007-1011.[CrossRef][Medline]
4 - du Plessis, D. G., R. Warren, M. Richardson, J. J. Joubert, and P. D. van Helden. 2001. Demonstration of reinfection and reactivation in HIV-negative autopsied cases of secondary tuberculosis: multilesional genotyping of Mycobacterium tuberculosis utilizing IS6110 and other repetitive element-based DNA fingerprinting. Tuberculosis 81:211-220.
5 - Fleischmann, R. D., D. Alland, J. A. Eisen, L. Carpenter, O. White, J. Peterson, R. DeBoy, R. Dodson, M. Gwinn, D. Haft, E. Hickey, J. F. Kolonay, W. C. Nelson, L. A. Umayam, M. Ermolaeva, S. L. Salzberg, A. Delcher, T. Utterback, J. Weidman, H. Khouri, J. Gill, A. Mikula, W. Bishai, W. R. Jacobs, Jr., J. C. Venter, and C. M. Fraser. 2002. Whole-genome comparison of Mycobacterium tuberculosis clinical and laboratory strains. J. Bacteriol. 184:5479-5490.[Abstract/Free Full Text]
6 - Friedman, C. R., M. Y. Stoeckle, W. D. Johnson Jr, and L. W. Riley. 1995. Double repetitive element PCR method for subtyping Mycobacterium tuberculosis clinical isolates. J. Clin. Microbiol. 33:1064-1069.[Abstract]
7 - Garnier, T., K. Eiglmeier, J. C. Camus, N. Medina, H. Mansoor, M. Pryor, S. Duthoy, S. Grondin, C. Lacroix, C. Monsempe, S. Simon, B. Harris, R. Atkin, J. Doggett, R. Mayes, L. Keating, P. R. Wheeler, J. Parkhill, B. G. Barrell, S. T. Cole, S. V. Gordon, and R. G. Hewinson. 2003. The complete genome sequence of Mycobacterium bovis. Proc. Natl. Acad. Sci. USA 100:7877-7882.[Abstract/Free Full Text]
8 - Kivi, M., X. Liu, S. Raychaudhuri, R. B. Altman, and P. M. Small. 2002. Determining the genomic locations of repetitive DNA sequences with a whole-genome microarray: IS6110 in Mycobacterium tuberculosis. J. Clin. Microbiol. 40:2192-2198.[Abstract/Free Full Text]
9 - Kot
owski, R., and R. Tylingo. 2003. Oligonucleotide repeats in genomes. Department of Food Chemistry and Technology, Gdansk University of Technology, Gdansk, Poland. [Online.] http://www.pg.gda.pl/chem/Katedry/Zywnosc/oligos.html.
10 - Otal, I., S. Samper, M. P. Asensio, M. A. Vitoria, M. C. Rubio, R. Gomez-Lus, and C. Martin. 1997. Use of a PCR method based on IS6110 polymorphism for typing Mycobacterium tuberculosis strains from BACTEC cultures. J. Clin. Microbiol. 35:273-277.[Abstract]
11 - Prod'hom, G., B. Lagier, V. Pelicic, A. J. Hance, B. Gicquel, and C. Guilhot. 1998. A reliable amplification technique for the characterization of genomic DNA sequences flanking insertion sequences. FEMS Microbiol. Lett. 158:75-81.[CrossRef][Medline]
12 - Poulet, S., and S. T. Cole. 1995. Repeated DNA sequences in mycobacteria. Arch. Microbiol. 163:79-86.[Medline]
13 - van Embden, J. D., M. D. Cave, J. T. Crawford, J. W. Dale, K. D. Eisenach, B. Gicquel, P. Hermans, C. Martin, R. McAdam, T. M. Shinnick, et al. 1993. Strain identification of Mycobacterium tuberculosis by DNA fingerprinting: recommendations for a standardized methodology. J. Clin. Microbiol. 31:406-409.[Abstract/Free Full Text]
14 - van Rie, A., R. Warren, M. Richardson, T. C. Victor, R. P. Gie, D. A. Enarson, N. Beyers, and P. D. van Helden. 1999. Exogenous reinfection as a cause of recurrent tuberculosis after curative treatment. N. Engl. J. Med. 341:1174-1179.[Abstract/Free Full Text]
15 - van Soolingen, D., P. W. Hermans, P. E. de Haas, D. R. Soll, and J. D. van Embden. 1991. Occurrence and stability of insertion sequences in Mycobacterium tuberculosis complex strains: evaluation of an insertion sequence-dependent DNA polymorphism as a tool in the epidemiology of tuberculosis. J. Clin. Microbiol. 29:2578-2586.[Abstract/Free Full Text]
16 - World Health Organization. 2002. Tuberculosis. Fact sheet no. 104. World Health Organization, Geneva, Switzerland. [Online.] http://www.who.int/mediacentre/factsheets/who104/en/index.html.
Journal of Clinical Microbiology, January 2004, p. 372-377, Vol. 42, No. 1
0095-1137/04/$08.00+0 DOI: 10.1128/JCM.42.1.372-377.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.
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