Profiling the Host-pathogen Interaction of Yersinia Pestis, the Causative Agent of Plague and the Immune Response of the Coyote, a Disease Refractory Host PDF Download

Author: Giulia Vernati
Publisher:
ISBN: 9781124296951
Category : Coyote
Languages : en
Pages : 55

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Book Description
Yersinia pestis, the bacterium responsible for causing plague, is identified by the Centers of Disease Control (CDC) as a category A bioterrorism agent. Although classified as a "high virulence" pathogen, some host species while susceptible to infection, are resistant to disease. As such, coyotes (Canis latrans) generally exhibit mild, if any symptoms during infection, but with stimulation of adaptive immunity as evidenced by development of a humoral immune response. In an effort to further define the nature of the coyote antibody response to plague and its potential role in contributing to the disease-refractory nature of this host, a qualitative serologic analysis was conducted to assess differences and similarities in the anti-plague antibody repertoire when compared with disease-susceptible hosts. Western blots of Yersinia pestis plasmid-encoded recombinant proteins were examined with pooled rabbit, coyote and prairie dog serum from animals with serologically-confirmed Y. pestis infections. The rabbit serum originated from animals which were experimentally infected via aerosol route or subcutaneously with wt Yersinia pestis CO92. The coyote serum was collected from free-range coyotes and the presence of antibodies to Y. pestis F1 antigen serologically confirmed. The prairie dog serum was collected from colony survivors of epizootic outbreak's occurring in two distinct geographic locations i.e. Colorado and Texas. When comparisons among the different species were made, results revealed a similar antibody profile exists between the coyote, Colorado colony prairie dog and rabbits infected subcutaneously. Similarly, the Texas colony prairie dogs shared a similar profile to the rabbits experimentally infected via aerosol route. These results suggest that among other factors, host response may be dependent on the organism's route of entry. Additionally, assessment of the immunogenicity of several Y. pestis virulence proteins, which have been previously characterized in a rodent model, was performed using individual coyote sera samples, which were previously confirmed as either sero-positive or sero-negative. The results revealed that coyotes mount an immune response to many of the same plasmid encoded antigens as do mice. However, the frequency of antibody response to some of the antigens differed between these two host species. Again, this may be attributable to route of infection. In vivo-induced antigen technology (IVIAT) was also employed to identify novel virulence genes of Y. pestis which are up-regulated in vivo during infection in the coyote, and compared to both the rabbit and prairie dog host. Pooled immune coyote serum was adsorbed multiple times with broth cultures of Y. pestis grown at 37°C to remove antibodies reactive to constitutively expressed antigens. Plasmid expression libraries of genomic and pFra/pPst plasmid DNA from a pLcr - strain of Y. pestis was then screened by colony immunoblot using the adsorbed sera. The IVI gene set between hosts were compared, and selected loci, PCR-amplified, cloned, and expressed in their entirety to obtain recombinant products for further study. IVIAT screens against the chromosomal expression library revealed coyote serum to be reactive to five IVI genes. To include: fliP, an inner membrane, flagellar assembly protein; SltY, a soluble lytic transglycosylase protein involved in cell-wall remodeling, and LepA, a highly conserved protein, which facilitates tRNA/ribosomal back-translocation. Upon cross-screening the reactive IVI clones with immune serum from rabbit and prairie dog, it was observed that FliP was uniquely reactive to the coyote serum. Variability of IVI antigen immune signatures suggests differential up-regulation/expression of Y. pestis virulence factors in different animal hosts, and/or differential immune responses to antigens relevant to Y. pestis survival during infection. Although screening of the plasmid expression library did not yield identification of novel genes, reactivity to plasminogen activator and pesticin supports the findings generated in the Western Blot analysis. The data collected through this study provided insight into the dissimilarities and similarities in the immune response of Canis latrans during Y. pestis infection when compared with infected immune sera from plague-sensitive hosts, which may relate to the pattern of immune resistance observed in canines to this otherwise highly lethal bacterial agent.