Submitted to: Japanese Society of Veterinary Science Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2003
Publication Date: N/A
Technical Abstract: Salmonella is known to induce apoptosis in host macrophages although the organisms are the facultative intracellular bacteria causing systemic dissemination by their survival within the host macrophages. Apoptosis may lead to systemic dissemination by repeating the process in which the intracellular bacteria are released outside the cells, thereby resulting in phagocytosis of Salmonella by new phagocytes again. In this study, the interaction of chicken macrophages and Salmonella enterica serovars Enteritidis and Typhimurium (SE and ST, respectively), which have been isolated frequently from not only the cases of human food poisoning and also poultry farms, were compared. The results showed that SE was less prone to induce apoptosis and did not elicit nitric oxide (NO) in macrophages than ST. This alteration of macrophage response to the different serovars may be involved in the SE-unique mechanism of egg contamination. Moreover, we investigated the effects of CpG oligodinucleotide (ODN) and interferon g (IFN-g), which have currently shown their immunomodulatory effects, on Salmonella-infected macrophages. CpG ODN induced iNOS-dependent apoptosis accompanied by high NO production in the infected macrophages. IFN-g, on the other hand, induced apoptosis, elicited NO production, and reduced the bacterial replication within the macrophages. From these results, CpG and IFN-g, despite the difference of serovars, can enhance not only the extracellular killing of Salmonella by increased NO pr duction and apoptosis induction but also the intracellular killing. It is therefore suggested that CpG and IFN-g are capable in use as the novel preventive strategy against chicken salmonellosis and egg contamination.