Figure 3. Genomic characteristics of 45 newly isolated S. Gallinarum biovar Pullorum (bvSP) strains from Taishun and Yueqing, Zhejiang Province, China.

(a) The phylogenetic tree, constructed using core-genome single nucleotide polymorphism sites (cgSNPs), categorizes the 45 bvSP strains into two distinct lineages (L3b and L2b). On the left side of the heatmap, information on isolation regions, sequence types (STs), and sampling times are displayed, with various colors indicating different categories as specified on the left. The right section of the heatmap presents a detailed matrix showing plasmids, antimicrobial resistance genes (ARGs), and cgSNP distances. The presence of a plasmid or ARG in an isolate is denoted by gray shading, while absence is indicated by white. cgSNPs below two were used as the threshold, with red circles signifying a higher probability of transmission between isolate pairs. (b) The average cgSNP distance between isolates from Taishun and Yueqing. E404 led to an increase in the mean cgSNP distance of bvSP from Taishun. (c) Invasiveness index of bvSP in Taishun and Yueqing. The results show a higher invasiveness index for bvSP isolated from Taishun, indicating that bvSP isolated from Taishun might have greater invasive capabilities among vulnerable hens.

Figure 3—figure supplement 1. Potential transmission events (n=53) of S. Gallinarum biovar Pullorum (bvSP).

The core-genome single nucleotide polymorphism site (cgSNP) distances were calculated between the bvSP strains isolated from Zhejiang Province (n=95) and those from China with available provincial information (n=435). Only cgSNP distances less than two are depicted, with darker colors indicating a higher transmission event.