The Pathogenesis of Salmonella enterica Serovar Enteritidis in Subcutaneously Infected Pigeon: A Quantitative Time-Course Study Using Real-Time PCR

This research was undertaken to determine the pathogenesis of a high-virulence strain of Salmonella enterica serovar Enteritidis in pigeon by a fluorescent quencher PCR assay and to correlate these findings with the results obtained from the immunohistochemical localization and histopathological examinations of selected Salmonella enterica serovar Enteritidis-infected tissues. To make the results meaningful, a side-by-side bacteriology method (indirect immuno-fluorescent antibody staining) was performed too. Pigeons were subcutaneously infected with a high-virulence strain of Salmonella enterica serovar Enteritidis. The kinetics of the Salmonella enterica serovar Enteritidis genomic DNA loads, the immunohistochemical localization of the bacterial antigens and the histopathological examination in various tissues were investigated. The results showed that at 12 h postinoculation, high Salmonella enterica serovar Enteritidis DNA loads were observed in various organs of the infected pigeons. Thereafter, the bacterial DNA loads increased by various amounts until 36 h postinoculation and the pigeons exhibited typical clinical signs of the infection. Extremely high bacterial DNA loads were observed in the pigeons at 36 and 48 h postinoculation compared with those observed at 8-24 h postinoculation. The results of indirect immuno-fluorescent antibody staining were similar to the fluorescent quencher PCR assay. The time course of the appearance of bacterial antigens and tissue lesions in various tissues was coincident with the levels of the bacterial DNA loads at the infection sites. This suggests that Salmonella enterica serovar Enteritidis loads in internal organs are closely correlated with the progression of the infection.