Figure 4

Analysis of variable regions in the C. jejuni genome. (A) Hierarchical clustering (Euclidian distance, average linking) based on the entire CGH dataset. The probes are ordered according to their position in the genome, starting with the probe targeting gene Cj0001 at the bottom of the figure. The log₂ ratio (M-values) of each probe is represented using a color gradient from yellow to blue, denoting M-values ranging from 0 to -7. A negative M-value indicates that the probe shows sequence divergence or absence in the test isolate compared to the NCTC 11168 reference strain. The PFGE genotypes and MLST sequence types are shown below. (B) Presence of variable regions in the analyzed isolates. On the y-axis are the five types of isolates (A, B, C, D and H) included in the study. The height of the bars corresponds to the number of isolate types in which the variable region was identified. The width of each bar is drawn proportional to the number of genes in the corresponding variable region. Regions 1–16 were described by Taboada et al. [27] and regions 17–18 by Parker et al. [29]. Regions 19–21 were identified in this study. (C) Analysis of the divergent genes shows that these represent multiple COG groups, as exemplified for isolate C20. Description of the COG groups is available through the COG database [33]. (D) The representation of COG groups among the variable genes was analyzed using Fisher exact test and the results are summarized using color coding. Groups M and V were significantly overrepresented among the variable genes in multiple isolates.