The iap mutation in strain 36-25-1 occurred between the LysM domain and the SH3 structure. Therefore, we conclude that this mutation has almost no influence on the functions of these domains. Pathogenicity of InlA truncated strain The results of the present study indicate that, except for InlA-mediated cell invasiveness, virulence in the InlA-truncated MK5108 36-25-1 strain is almost equivalent to that in a clinical wild-type strain. However, these results differ from those of a study by Témoin et al. (2008), which demonstrated that 3 virulence genes, including inlA, were simultaneously truncated [17]. In addition, Van Stelten et al. (2011), after orally

administering an InlA-truncated strain to guinea pigs, reported that only the translocation rate to the spleen was lower in the truncated strain, when compared to a clinical wild-type strain [14]. Moreover, in the study by Olier et al. (2005) using

a strain that originally showed virulence but was genetically modified to express truncated InlA, the mortality of chicken embryos infected with the transformed strain was lower than that BKM120 of chickens infected with a clinical wild-type strain [13]. These reports indicate that aspects of virulence other than cell invasiveness differ between InlA-truncated buy TPCA-1 strains and clinical wild-type strains; this cannot be explained by the results of the present study. Therefore, we expect that mutations in the virulence-associated genes of InlA-truncated strains will exhibit heterogeneity. The results from InlA-truncated strains other than strain 36-25-1

in the present study support this hypothesis. In addition, many L. monocytogenes genes have functions that are not yet elucidated. Hence, we cannot exclude the possibility that genes not analyzed in the present study contribute to the differences between InlA-truncated strains and clinical wild-type strains. Analyzing other InlA-truncated strains and determining the unknown functions of L. monocytogenes genes will resolve these questions. Conclusions In the present study, we analyzed the major virulence-associated genes in strain 36-25-1, an InlA-truncated strain. With the exception of inlA, the virulence-associated genes in the InlA-truncated eltoprazine strain are almost identical to those in a clinical wild-type strain. The results indicate that a slight mutation in the nucleotide sequence, such as a PMSC, determines the virulence of InlA-truncated strains. In addition, post-translational analysis of each gene indicated that, except for InlA-mediated cell invasiveness, the virulence of the 36-25-1 strain is equivalent to that of clinical wild-type strains. However, this result does not completely explain the results of previous studies on InlA-truncated strains.