Abstract 940 Human Milk Poster Symposium, Sunday, 5/2

Introduction: Invasion of epithelial cells is an essential step to the development of infections caused by enteropathogens. Previously, we have shown that recombinant human lactoferrin (rhLF) decreases significantly the invasiveness of Shigella flexneri 5 M90T in a HeLa cell model; and that this decrease in invasiveness is associated with loss and degradation of IpaB and IpaC, two surface expressed virulence markers from Shigella.

Purpose: Therefore, we sought to determine whether rhLF at physiologic concentrations would prevent the invasion of other enteropathogens that have similar type III secretory system mechanisms of virulence.

Methods: Shigella flexneri 35406, Salmonella typhi strain 9993, enteroinvasive E. coli (EIEC) strains CID200, and CID212, and enterohemorrhagic E. coli (EHEC) strain 8624 were used in a HeLa cell model. Bacteria were briefly (1 hr) incubated with lactoferrin (10 mg/mL) or buffer (for controls), washed and resuspended in cell culture media. HeLa cells were challenged with the bacteria at a bacteria:cell ratio of 100:1. After a 2-hr incubation (3.5 hr for EHEC) the cells were washed and overlayed with gentamicin for 1 hr (2.5 hr for EHEC); then the cells were lysed and colony counts were performed.

Results: (Table)

Table 1 No caption
Full size table

Conclusions: Very brief exposure to lactoferrin at the concentration normally found in colostrum decreases significantly the invasiveness of a variety of bacteria which share related virulence mechanisms.

This work was funded in part by NIH-PO1 HD-13021 and Agennix Inc.