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Title: MIXED-GENOME MICROARRAYS REVEAL MULTIPLE SEROTYPE AND LINEAGE-SPECIFIC DIFFERENCES AMONG STRAINS OF LISTERIA MONOCYTOGENES

Author
item CALL, DOUGLAS - WASHINGTON STATE UNIV
item Borucki, Monica
item BESSER, THOMAS - WASHINGTON STATE UNIV

Submitted to: Journal of Clinical Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2002
Publication Date: 2/20/2003
Citation: Call, D.R., Borucki, M.K., Besser, T. Mixed-genome microarrays reveal multiple serotype and lineage-specific differences among strains of listeria monocytogenes. Journal of Clinical Microbiology. 2003. v. 41(2). p. 632-639.

Interpretive Summary: This manuscript describes the use of DNA microarray technology for the subtyping of Listeria monocytogenes isolates and for the identification of virulence-associated genes. Previously-described phylogenetic linages were confirmed using microarray analysis as was the clonal nature of L. monocytogenes species. Additionally, microarray analysis allowed the identification of serotype specific probe sequences.

Technical Abstract: Epidemiological studies and analysis of putative virulence genes have shown that Listeria monocytogenes has diverged into several phylogenetic divisions. We hypothesize that similar divergence has occurred for many other genes that influence niche-specific fitness and virulence. To explore this issue further, we developed a microarray composed of fragmented DNA taken from ten strains of L. monocytogenes. We then hybridized genomic DNA from 50 different strains to replicate arrays and analyzed the resulting hybridization patterns. A simple Euclidean distance metric permitted reconstruction of previously described genetic relationships between serotypes and only four microarray probes were needed to discriminate between the most important serotypes (1/2a, 1/2b, 1/2c and 4). We calculated an index of linkage equilibrium from the microarray data and confirmed that L. monocytogenes has a strongly clonal population structure (IA = 3.85). Twenty-nine informative probes were retrieved from the library and sequenced. These included genes associated with repairing UV damaged DNA, salt tolerance, biofilm formation, heavy metal transport, ferrous iron transport, and teichoic acid synthesis. Several membrane bound lipoproteins and one internalin were identified plus three phage sequences and six sequences with unknown function. Collectively, these data confirm that many genes have diverged between lineages of L. monocytogenes.