Interaction Differences of the Avian Host-Specific Salmonella enterica Serovar Gallinarum, the Host-Generalist . Typhimurium, and the Cattle Host-Adapted . Dublin with Chicken Primary Macrophage.

Most serovars cause disease in many host species, while a few serovars have evolved to be host specific. Very little is known about the mechanisms that contribute to host specificity. We compared the interactions between chicken primary macrophages (CDPM) and host-generalist serovar serovar Typhimurium, host-adapted serovar Dublin, and avian host-specific serovar Gallinarum. Gallinarum was taken up in lower numbers by CDPM than Typhimurium and Dublin; however, a higher survival rate was observed for this serovar. In addition, Typhimurium and Dublin caused substantially higher levels of cell death to the CDPM, while significantly higher concentrations of NO were produced by Gallinarum-infected cells. Global transcriptome analysis performed 2 h postinfection showed that Gallinarum infection triggered a more comprehensive response in CDPM with 1,114 differentially expressed genes (DEGs) compared to the responses of Typhimurium (625 DEGs) and Dublin (656 DEGs). Comparable levels of proinflammation responses were observed in CDPM infected by these three different serovars at the initial infection phase, but a substantially quicker reduction in levels of interleukin-1β (IL-1β), CXCLi1, and CXCLi2 gene expression was detected in the Gallinarum-infected macrophages than that of two other groups as infections proceeded. KEGG cluster analysis for unique DEGs after Gallinarum infection showed that the JAK-STAT signaling pathway was top enriched, indicating a specific role for this pathway in response to Gallinarum infection of CDPM. Together, these findings provide new insights into the interaction between and the host and increase our understanding of Gallinarum host specificity.