On the other hand, the missense mutation in gtcA found in 36-25-1 was not found in the other InlA-truncated strains (Figure 1B). As for the tandem repeat of the ACAAAT motif in iap, strains Lma13, Lma15, and Lma20 had 3 repeats; strain Lma28 had 2 repeats (Figure 1C). Discussion Virulence-related genes in strain 36-25-1

The contig of the 36-25-1 strain constructed by de novo assembly showed similarity as high as 99.84% PRIMA-1MET nmr in the regions that aligned with the EGDe strain. In addition, this strain possessed all of the 36 virulence-associated genes analyzed. The genus Listeria is considered to have lost virulence-associated genes as it differentiated from ancestors that showed virulence [19]. Multiple virulence-associated genes are missing in strain 4a, a serotype of L. monocytogenes showing no virulence [20]. Because strain 36-25-1 possesses all of the 36 genes investigated in the present study, we conclude that the selleck chemicals InlA-truncated strain has not undergone changes that have resulted in any major loss of regions present in the clinical wild-type strain. Virulence-related genes with mutations Among the 36 virulence-associated genes in strain 36-25-1, 32 genes possess

a sequence identical to that of the corresponding gene in the EGDe strain. Selleck VX-661 Therefore, we conclude that the virulence of these genes is the same in the 36-25-1 and EGDe strains. Nucleotide sequence differences were found in only 4 genes (dltA, gtcA, iap, and inlA). dltA is a part of the Erastin dlt operon, which is composed of 4 genes that function in the addition of alanine to lipoteichoic acid (LTA) [21]. Experiments using a strain in which dltA was artificially inactivated suggest that dltA influences the electric charge of the bacterial surface to increase adhesiveness to host cells [22]. The dltA mutation found in strain 36-25-1 is present in all other InlA-truncated strains examined in this study. Whether or not this mutation is characteristic of InlA-truncated strains requires investigation of other clinical wild-type strains. However, this mutation does not influence

the phenotype of these strains as a silent mutation. Similar to dltA, gtcA is involved in the addition of a saccharide to LTA [21]. In the present study, the nucleotide sequence of gtcA in strain 36-25-1 differed from that in the EGDe strain, and the encoded amino acid sequence differed as well. However, this mutation is not common to InlA-truncated strains: the mutation was not found in the other InlA-truncated strains examined. The mutation in iap is in the tandem repeat region, in which the number of repeats has been reported to vary even among clinical wild-type strains [23–26]. p60, encoded by iap, is involved in the movement of L. monocytogenes inside a host cell and in cell-to-cell propagation [24]. p60 possesses multiple LysM motifs at its C-terminus, which are used to bind to the cell wall of L.