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Francisella tularensis is pathogenic for many mammalian species including humans, causing a spectrum of diseases called tularemia. The highly virulent Type A strains have associated mortality rates of up to 60% if inhaled. An attenuated live vaccine strain (LVS) is the only vaccine to show efficacy in humans, but suffers several barriers to licensure, including the absence of a correlate of protection. An immunoproteomics approach was used to survey the repertoire of antibodies in sera from individuals who had contracted tularemia during two outbreaks and individuals from two geographical areas who had been vaccinated with NDBR Lot 11 or Lot 17 LVS. These data showed a large overlap in the antibodies generated in response to tularemia infection or LVS vaccination. A total of seven proteins were observed to be reactive with 60% or more sera from vaccinees and convalescents. A further four proteins were recognised by 30-60% of the sera screened. These proteins have the potential to serve as markers of vaccination or candidates for subunit vaccines. Crown Copyright (C) 2011 Published by Elsevier GmbH. All rights reserved.

Understanding the pathogenesis of infectious diseases requires comprehensive knowledge of the proteins expressed by the pathogen during in vivo growth in the host. Proteomics provides the tools for such analyses but the protocols required to purify sufficient quantities of the pathogen from the host organism are currently lacking. Here, we present a rapid immunomagnetic protocol for the separation of Francisella tularensis, a highly virulent bacterium and potential biowarfare agent, from the spleens of infected mice. In less than one hour, bacteria can be isolated in quantities sufficient to carry out meaningful proteomic comparisons with in vitro grown bacteria. Furthermore, the isolates are virtually free from contaminating host proteins. Two-dimensional gel analysis revealed a host induced proteome in which 78 proteins were differentially expressed in comparison to in vitro grown controls. The results obtained clearly demonstrate the complexity of the adaptive response of F. tularensis to the host environment, and the difficulty of mimicking such behavior in vitro.