Invasion of Epithelial Cells byYersinia pestis: Evidence for aY. pestis-Specific Invasin

Abstract

The causative agent of plague, Yersinia pestis, is regarded as being noninvasive for epithelial cells and lacks the major adhesins and invasins of its enteropathogenic relatives Yersinia enterocolitica and Yersinia pseudotuberculosis. However, there are studies indicating that Y. pestis invades and causes systemic infection from ingestive and aerogenic routes of infection. Accordingly, we developed a gentamicin protection assay and reexamined invasiveness of Y. pestis for HeLa cells. By optimizing this assay, we discovered that Y. pestis is highly invasive. Several factors, including the presence of fetal bovine serum, the configuration of the tissue culture plate, the temperature at which the bacteria are grown, and the presence of the plasminogen activator protease Pla-encoding plasmid pPCP1, were found to influence invasiveness strongly. Suboptimal combinations of these factors may have contributed to negative findings by previous studies attempting to demonstrate invasion by Y. pestis. Invasion of HeLa cells was strongly inhibited by cytochalasin D and modestly inhibited by colchicine, indicating strong and modest respective requirements for microfilaments and microtubules. We found no significant effect of the iron status of yersiniae or of the pigmentation locus on invasion and likewise no significant effect of the Yops regulon. However, an unidentified thermally induced property (possibly the Y. pestis-specific capsular protein Caf1) did inhibit invasiveness significantly, and the plasmid pPCP1, unique to Y. pestis, was essential for highly efficient invasion. pPCP1 encodes an invasion-promoting factor and not just an adhesin, because Y. pestis lacking this plasmid still adhered to HeLa cells. These studies have enlarged our picture of Y. pestis biology and revealed the importance of properties that are unique to Y. pestis.

Genome sequence of Yersinia pestis, the causative agent of plague

“…A 9.5-kb plasmid (pPst/pPCP1) encodes the plasminogen activator Pla (ref. 8), a putative invasin that is essential for virulence by the subcutaneous route. A 100±110-kb plasmid (pFra/pMT1) encodes murine toxin Ymt and the F1 capsular protein, which have been shown to have a role in the transmission of plague.…”

“…Rough mutants of Y. enterocolitica show an enhanced ability to invade cultured cells, a suggested consequence of the enhanced accessibility of surface Ail 28 . However, a recent mutagenesis study in Y. pseudotuberculosis found that O-antigen mutants were unable to invade epithelial cells 29 and were attenuated when infecting mice both orally and systemically, suggesting that as Y. pestis is invasive 8 and virulent, it may have alternative surface structures that complement the loss of the O antigen.…”

“…Understanding post-trauma events and developing neuroprotective agents are therefore important 8 . Cannabinoids act through two distinct receptors, one of which (CB 1 ) is found mainly in the brain.…”

Phenotypic characterization of OmpX, an Ail homologue of Yersinia pestis KIM

“…In airborne disease, penetration of epithelial cells may promote development of pulmonary lesions . Although Pla protease enhances interaction with epithelial cells (Cowan et al, 2000;Lahteenmaki et al, 1998Lahteenmaki et al, , 2001a, Psa fimbria have also been implicated. Neither is sufficient to confer complete internalization.…”

“…pestis enters epithelial cells, another mechanism to circumvent the immune response (Cowan et al, 2000). In airborne disease, penetration of epithelial cells may promote development of pulmonary lesions .…”