In vitro attachment and invasion of chicken ovarian granulosa cells by Salmonella enteritidis phage type 8

The attachment and invasion of chicken ovarian granulosa cells by Salmonella enteritidis was examined in vitro. The attachment was inhibited by preincubation of granulosa cells with anti-chicken fibronectin antibody (approximately 70% reduction in attachment) or preincubation with a 14-kDa fimbrial protein isolated from S. enteritidis (68% reduction in attachment). Treatment of bacterial cells with the tetrapeptide RGDS before addition to granulosa cells resulted in inhibition of attachment (60% inhibition when 2 x 10(7) CFU of bacteria was treated with 500 mu g of peptide). Treatment with the peptide GRGD resulted in similar magnitude of inhibition, indicating that extracellular matrix proteins play significant roles in the interaction of S. enteritidis with granulosa cells. In contrast, treatment of the bacterial cells with the peptide GRAD did not result in significant inhibition of attachment to the granulosa cells. S. enteritidis was found to attach specifically to fibronectin, collagen IV, and laminin-coated microtiter plate wells, with the rank order of attachment as follows: fibronectin > laminin > collagen N. Light and transmission electron micrographs of S. enteritidis invasion of granulosa cells showed organisms with or without a surrounding membrane in the cytoplasm of granulosa cells. In some instances, dividing bacterial cells were observed in the cytoplasm. Results of this study demonstrated that S. enteritidis interacts with granulosa cells in a specific manner and can invade and multiply in these cells. The granulosa cell layer of the preovulatory follicles may be a preferred site for the colonization of the chicken ovaries by invasive strains of S. enteritidis.