Variation of the lap gene region (407bp) encoding an invasion-associated pr
otein p60 was studied on 12 strains of Listeria monocytogenes of different
origin in Japan. These 12 strains are known to have 2 types of serotype (1/
2a and 4b) and have a diversity among the strains (Saito et al., 1998). The
dye-primer cycle sequencing method was employed to determine the genomic s
tructure, and the nucleotide sequences obtained were compared with those of
reference strain SV 1/2a EGD.
Differences found in the nucleotides were as follows; point mutations of 33
variations in 32 places; an insertion and 3 deletions of 3 bases; AAT posi
tion (po.) 1282-1283, and GCA po. 1307-1309, ACA po. 1412-1414, AAT po. 143
9-1444, respectively. Different repeating numbers by 6 base unit, ACA AAT,
were also found in the tandem repeat region (po. 1394-1423). Classification
of 12 strains was attempted, then 8, 4 and 5 types were obtained from the
point mutations, the insertions and deletions, and the repeating numbers, r
espectively. Consequently, 8 patterns were profiled regardless of each sero
type.
From these results, genomic structures were partially clarified in the lap
gene 407bp of L. monocytogenes isolated in Japan. Then, the possibility of
detailed epidemiology for L. monocytogenes infection using a combination of
serotype and genome structure was suggested because of the previous polymo
rphism thought to be due to the nucleotide differences in the region.