Résumé
The worldwide threat of tuberculosis to human health
emphasizes the need to develop novel approaches to a global
epidemiological surveillance. The current standard for
Mycobacterium tuberculosis typing based on
IS6110 restriction fragment length polymorphism (RFLP)
suffers from the difficulty of comparing data between independent
laboratories. Here, we propose a high-resolution typing method based on
variable number tandem repeats (VNTRs) of genetic elements named
mycobacterial interspersed repetitive units (MIRUs) in 12 human
minisatellite-like regions of the M. tuberculosis
genome. MIRU-VNTR profiles of 72 different M.
tuberculosis isolates were established by PCR analysis of all
12 loci. From 2 to 8 MIRU-VNTR alleles were identified in the 12
regions in these strains, which corresponds to a potential of over 16
million different combinations, yielding a resolution power close to
that of IS6110-RFLP. All epidemiologically related
isolates tested were perfectly clustered by MIRU-VNTR typing,
indicating that the stability of these MIRU-VNTRs is adequate to track
outbreak episodes. The correlation between genetic relationships
inferred from MIRU-VNTR and IS6110-RFLP typing was
highly significant. Compared with IS6110-RFLP,
high-resolution MIRU-VNTR typing has the considerable advantages of
being fast, appropriate for all M. tuberculosis
isolates, including strains that have a few IS6110
copies, and permitting easy and rapid comparison of results from
independent laboratories. This typing method opens the way to the
construction of digital global databases for molecular epidemiology
studies of M. tuberculosis.