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Hamilton, MT, United States

Kubinak J.L.,University of Utah | Ruff J.S.,University of Utah | Cornwall D.H.,University of Utah | Middlebrook E.A.,University of Utah | And 2 more authors.
Genes and Immunity | Year: 2013

Using an experimental evolution approach, we recently demonstrated that the mouse-specific pathogen Friend virus (FV) complex adapted to specific major histocompatibility complex (MHC) genotypes, which resulted in fitness tradeoffs when viruses were exposed to hosts possessing novel MHC polymorphisms. Here we report the analysis of patterns of pathogen adaptation and virulence evolution from viruses adapting to one of three hosts that differ across the entire genome (A/WySn, DBA/2J and BALB/c). We found that serial passage of FV complex through these mouse genotypes resulted in significant increases in pathogen fitness (156-fold) and virulence (11-fold). Adaptive responses by post-passage viruses also resulted in host-genotype-specific patterns of adaptation. To evaluate the relative importance of MHC versus non-MHC polymorphisms as factors influencing pathogen adaptation and virulence, we compared the magnitude of fitness tradeoffs incurred by post-passage viruses when infecting hosts possessing either novel MHC polymorphisms alone or hosts possessing novel MHC and non-MHC polymorphisms. MHC polymorphisms alone accounted for 71% and 83% of the total observed reductions in viral fitness and virulence in unfamiliar host genotypes, respectively. Strikingly, these data suggest that genetic polymorphisms within the MHC, a gene region representing only ∼0.1% of the genome, are major host factors influencing pathogen adaptation and virulence evolution. Source

Bridge D.R.,West Virginia University | Bridge D.R.,Uniformed Services University of the Health Sciences | Martin K.H.,West Virginia University | Moore E.R.,West Virginia University | And 5 more authors.
Infection and Immunity | Year: 2012

The opportunistic pathogen Pseudomonas aeruginosa targets wounded epithelial barriers, but the cellular alteration that increases susceptibility to P. aeruginosa infection remains unclear. This study examined how cell migration contributes to the establishment of P. aeruginosa infections using (i) highly migratory T24 epithelial cells as a cell culture model, (ii) mutations in the type III secretion (T3S) effector ExoS to manipulate P. aeruginosa infection, and (iii) high-resolution immunofluorescent microscopy to monitor ExoS translocation. ExoS includes both GTPase-activating (GAP) and ADP-ribosyltransferase (ADPRT) activities, and P. aeruginosa cells expressing wild-type ExoS preferentially bound to the leading edge of T24 cells, where ExoS altered leading-edge architecture and actin anchoring in conjunction with interrupting T3S translocation. Inactivation of ExoS GAP activity allowed P. aeruginosa to be internalized and secrete ExoS within T24 cells, but as with wild-type ExoS, translocation was limited in association with disruption of actin anchoring. Inactivation of ExoS ADPRT activity resulted in significantly enhanced T3S translocation by P. aeruginosa cells that remained extracellular and in conjunction with maintenance of actinplasma membrane association. Infection with P. aeruginosa expressing ExoS lacking both GAP and ADPRT activities resulted in the highest level of T3S translocation, and this occurred in conjunction with the entry and alignment of P. aeruginosa and ExoS along actin filaments. Collectively, in using ExoS mutants to modulate and visualize T3S translocation, we were able to (i) confirm effector secretion by internalized P. aeruginosa, (ii) differentiate the mechanisms underlying the effects of ExoS GAP and ADPRT activities on P. aeruginosa internalization and T3S translocation, (iii) confirm that ExoS ADPRT activity targeted a cellular substrate that interrupted T3S translocation, (iv) visualize the ability of P. aeruginosa and ExoS to align with actin filaments, and (v) demonstrate an association between actin anchoring at the leading edge of T24 cells and the establishment of P. aeruginosa infection. Our studies also highlight the contribution of ExoS to the opportunistic nature of P. aeruginosa infection through its ability to exert cytotoxic effects that interrupt T3S translocation and P. aeruginosa internalization, which in turn limit the P. aeruginosa infectious process. © 2012, American Society for Microbiology. Source

Banki Zoltan,Innsbruck Medical University | Posch W.,Innsbruck Medical University | Ejaz A.,Innsbruck Medical University | Oberhauser V.,Innsbruck Medical University | And 6 more authors.
PLoS Pathogens | Year: 2010

Previous studies have demonstrated the involvement of complement (C) in induction of efficient CTL responses against different viral infections, but the exact role of complement in this process has not been determined. We now show that C opsonization of retroviral particles enhances the ability of dendritic cells (DCs) to induce CTL responses both in vitro and in vivo. DCs exposed to C-opsonized HIV in vitro were able to stimulate CTLs to elicit antiviral activity significantly better than non-opsonized HIV. Furthermore, experiments using the Friend virus (FV) mouse model illustrated that the enhancing role of complement on DC-mediated CTL induction also occurred in vivo. Our results indicate that complement serves as natural adjuvant for DC-induced expansion and differentiation of specific CTLs against retroviruses. Source

Baron G.S.,Laboratory of Persistent Viral Diseases | Hughson A.G.,Laboratory of Persistent Viral Diseases | Raymond G.J.,Laboratory of Persistent Viral Diseases | Offerdahl D.K.,Laboratory of Persistent Viral Diseases | And 4 more authors.
Biochemistry | Year: 2011

Mammalian prion diseases involve conversion of normal prion protein, PrPC, to a pathological aggregated state (PrPres). The three-dimensional structure of PrPres is not known, but infrared (IR) spectroscopy has indicated high, strain-dependent β-sheet content. PrPres molecules usually contain a glycophosphatidylinositol (GPI) anchor and large Asn-linked glycans, which can also vary with strain. Using IR spectroscopy, we tested the conformational effects of these post-translationalmodifications by comparing wild-type PrPres with GPI- and glycan-deficient PrP res produced in GPI-anchorless PrP transgenic mice. These analyses required the development of substantially improved purification protocols. Spectra of both types of PrPres revealed conformational differences between the 22L,ME7, andChandler (RML) murine scrapie strains,most notably in bands attributed to β-sheets. These PrPres spectra were also distinct from those of the hamster 263K scrapie strain. Spectra of wild-type and anchorless 22L PrPres were nearly indistinguishable. With ME7 PrPres, modest differences between the wild-type and anchorless spectra were detected, notably an ̃ 2 cm-1 shift in an apparent β-sheet band. Collectively, the data provide evidence that the glycans and anchor do not grossly affect the strain-specific secondary structures of PrPres, at least relative to the differences observed between strains, but can subtly affect turns and certain β-sheet components. Recently reported H-D exchange analyses of anchorless PrPres preparations strongly suggested the presence of strain-dependent, solvent-inaccessible β-core structures throughout most of the C-terminal half of PrPres molecules, with no remaining α-helix. Our IR data provide evidence that similar core structures also comprise wild-type PrPres. © 2011 American Chemical Society. Source

Moore R.A.,Laboratory of Persistent Viral Diseases | Sturdevant D.E.,National Institute of Allergy and Infectious Diseases | Chesebro B.,Laboratory of Persistent Viral Diseases | Priola S.A.,Laboratory of Persistent Viral Diseases
Journal of Proteome Research | Year: 2014

Prion diseases are a heterogeneous group of neurodegenerative disorders affecting various mammals including humans. Prion diseases are characterized by a misfolding of the host-encoded prion protein (PrPC) into a pathological isoform termed PrPSc. In wild-type mice, PrPC is attached to the plasma membrane by a glycosylphosphatidylinositol (GPI) anchor and PrPSc typically accumulates in diffuse nonamyloid deposits with gray matter spongiosis. By contrast, when mice lacking the GPI anchor are infected with the same prion inoculum, PrPSc accumulates in dense perivascular amyloid plaques with little or no gray matter spongiosis. In order to evaluate whether different host biochemical pathways were implicated in these two phenotypically distinct prion disease models, we utilized a proteomics approach. In both models, infected mice displayed evidence of a neuroinflammatory response and complement activation. Proteins involved in cell death and calcium homeostasis were also identified in both phenotypes. However, mitochondrial pathways of apoptosis were implicated only in the nonamyloid form, whereas metal binding and synaptic vesicle transport were more disrupted in the amyloid phenotype. Thus, following infection with a single prion strain, PrPC anchoring to the plasma membrane correlated not only with the type of PrPSc deposition but also with unique biochemical pathways associated with pathogenesis. © 2014 American Chemical Society. Source

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