Identification ofIn Vivo-Induced Conserved Sequences fromYersinia pestisDuring Experimental Plague Infection in the Rabbit

Abstract

In an effort to identify the novel virulence determinants of Yersinia pestis, we applied the gene "discovery" methodology, in vivo-induced (IVI) antigen technology, to detect genes upregulated during infection in a laboratory rabbit model for bubonic plague. After screening over 70,000 Escherichia coli clones of Y. pestis DNA expression libraries, products from 25 loci were identified as being seroreactive to reductively adsorbed, pooled immune serum. Upon sequence analysis of the predicted IVI gene products, more frequently encountered conserved protein functional categories have emerged, to include type-V autotransporters and components of more complex secretion systems including types III and VI. The recombinant products from eight selected clones were subsequently immunoblotted against pooled immune serum from two naturally infected host species: the prairie dog, and a species refractory to lethal disease, the coyote. Immune prairie dog serum recognized 2-3 of the rabbit-reactive antigens, suggesting at least some overlap in the pathogen's in vivo survival mechanisms between these two hosts. Although the coyote serum failed to recognize most of the IVI antigens, LepA was universally reactive with all three host sera. Collectively, the profiles/patterns of IVI conserved sequences (IVICS) may represent immune "signatures" among different host species, possessing the potential for use as a diagnostic tool for plague. Further, the antigenic nature of IVICS makes them ideal for further evaluation as novel subunit vaccine candidates. The gathering of additional data and analysis of the intact IVI genes and the expressed IVICS products should provide insight into the unique biologic processes of Y. pestis during infection and reveal the genetic patterns of the pathogen's survival strategy in different hosts.

Evolution and Virulence Contributions of the Autotransporter Proteins YapJ and YapK of Yersinia pestis CO92 and Their Homologs in Y. pseudotuberculosis IP32953

“…It is this N terminus of the protein that is of most interest, as it is the portion that varies the most among all of the genes of the yapJ-yapK family and is the portion most likely to be engaged in interactions with the host. Based on our previous work, we know that yapJ and yapK are induced during bubonic and pneumonic infections of mice (38), and reactivity against either YapJ or YapK (and two other Yaps) has also been detected in convalescent-phase sera from experimentally infected rabbits (7), indicating that at least one of these genes is induced following subcutaneous infections of rabbits. As surface-exposed proteins expressed during infection and recognized by the adaptive immune response, these proteins of unknown function represent potential targets for new vaccines.…”

“…However, it was shown that the expression of yapJ and yapK is induced during mammalian infection in both bubonic and pneumonic models of plague in C57BL/6 mice (38). In addition, antibodies against YapJ were detected following experimental infection in a sublethal rabbit model of bubonic plague when the sera of surviving rabbits were screened with an Escherichia coli library expressing Y. pestis proteins (7). While expression in a host implies a role in virulence, it remained unknown what role these genes might be playing during the infectious process.…”

Expression during Host Infection and Localization of Yersinia pestis Autotransporter Proteins

“…Additional studies have since indicated that a subset of these putative autotransporter proteins possesses adhesive and autoaggregative properties (24,42,72). As more investigation has been initiated into the virulence properties of Y. pestis, some of these putative autotransporter-encoding genes have arisen in genetic screens as having potential roles in host infection or encoding immunogenic proteins (4,27,43,71) though their contributions to pathogenesis remain largely undefined.…”

Proteolytic processing of the Yersinia pestis YapG autotransporter by the omptin protease Pla and the contribution of YapG to murine plague pathogenesis

“…In analysing expression of each of the yap genes by qRT-PCR, our previous work showed that yapG expression is modestly induced during bubonic and pneumonic plague in mice (Lenz et al , 2011). Additionally, the production of YapG-specific antibodies was demonstrated during a sublethal rabbit model of bubonic plague using in vivo -induced antigen technology (Andrews et al , 2010). Based on these data, and the observation that most characterized autotransporters are either implicated in virulence or have virulence-associated functions, it seems likely that YapG also contributes to Y. pestis pathogenesis.…”