The second group included 86 strains with a single ampli-
fied band, specific for the absence of the IS6110 insertion in
the target locus, hence indicative of other than the LAM family
(Table S1). Few observations can be made regarding the
discrepancies with spoligotype-defined families. Four of the
studied strains belonged to SIT41 defined in SITVIT_WEB as
LAM7-TUR. However, no LAM-specific band was amplified in
these strains; hence they cannot be defined as LAM. Indeed,
another online resource for M. tuberculosis molecular typing (MIRU-VNTRplus.org) defines the family of these strains as
TUR, based on the analysis of different molecular markers,
including VNTRs and SNPs. It is also interesting to note that
all studied strains of the SIT125, which had an uncertain family
definition (LAM/S in earlier SpolDB4 and T2/LAM3 in
SITVIT_WEB), did not have a LAM-specific band; hence their
family status cannot be LAM. Finally, two strains of SIT1588
had a single non-LAM band which is intriguing, since these
strains had a prototype LAM signature (see SIT42 in Fig. 1),
in addition to the deleted first signals. This profile may be a
result of the convergent evolution of the DR locus, and more
strains of this spoligotype SIT1588 should be studied in order
to verify its family status.
Regarding the third and smallest group of strains, it
included 4 strains with only LAM-specific band amplified.
One of them–strain 52–was assigned to LAM in SITVIT_WEB;
strain 8 was assigned to T5-RUS1, but it was recently shown
to belong to LAM [9]. In its turn, strain 126 (‘new’ spoligotype,
‘unknown’ family in SITVIT_WEB) may indeed belong to LAM
as confirmed herein by LAM-PCR. At the same time, strain 81
(SIT453/T) had LAM-specific band amplified, but intact
spacers 21–24; this discrepancy is unexpected and questions
the value of this IS6110-PCR as LAM-specific.