Background & Aims-Studies of hepatitis C virus (HCV) infection, immunopathogenesis, and resulting liver diseases have been hampered by the lack of a small animal model. We developed humanized mice with human immune system and liver tissues to improve the studies of hepatitis C pathogenesis and treatment.

The CPS1 gene was identified as a virulence factor in the maize pathogen Cochliobolus heterostrophus. Hypothesizing that the homologous gene in Coccidioides posadasii could be important for virulence, we created a ⌬cps1 deletion mutant which was unable to cause disease in three strains of mice (C57BL/6, BALB/c, or the severely immunodeficient NOD-scid,␥c null [NSG]). Only a single colony was recovered from 1 of 60 C57BL/6 mice following intranasal infections of up to 4,400 spores. Following administration of very high doses (10,000 to 2.5 ؋ 10 7 spores) to NSG and BALB/c mice, spherules were observed in lung sections at time points from day 3 to day 10 postinfection, but nearly all appeared degraded with infrequent endosporulation. Although the role of CPS1 in virulence is not understood, phenotypic alterations and transcription differences of at least 33 genes in the ⌬cps1 strain versus C. posadasii is consistent with both metabolic and regulatory functions for the gene. The in vitro phenotype of the ⌬cps1 strain showed slower growth of mycelia with delayed and lower spore production than C. posadasii, and in vitro spherules were smaller. Vaccination of C57BL/6 or BALB/c mice with live ⌬cps1 spores either intranasally, intraperitoneally, or subcutaneously resulted in over 95% survival with mean residual lung fungal burdens of <1,000 CFU from an otherwise lethal C. posadasii intranasal infection. Considering its apparently complete attenuation of virulence and the high degree of resistance to C. posadasii infection when used as a vaccine, the ⌬cps1 strain is a promising vaccine candidate for preventing coccidioidomycosis in humans or other animals. Coccidioides species (C. immitis and C. posadasii) are the causative agents of coccidioidomycosis (valley fever), an important emerging disease endemic to the southwestern United States and elsewhere in the Western Hemisphere (1-3). Inhalation of a 2-to 4-m arthroconidium (spore) initiates a respiratory infection and grows as a unique parasitic phase structure, the spherule, to 80 to 100 m in diameter (4). During spherule maturation, which in mice takes approximately 4 days, internal cell division and septation results in hundreds of endospores that, if released, can reinitiate spherule growth in the infected tissue. Although many infections resolve without medical intervention, about 40% of infections cause respiratory illnesses that often last weeks to many months (5). In a small percentage of patients, infection disseminates from the lungs hematogenously to produce progressive, protracted, and even fatal complications. With or without clinical illness, most infections produce lifelong immunity to a second coccidioidal infection, and it is this observation that suggests a preventative vaccine could be developed (6).Interest in CPS1 came first from a search for general virulence factors in the maize pathogen Cochliobolus heterostrophus. In this and other ascomycete cereal grain pathogens, deletion of the CPS1 gene results in reduced virulence on host plants with prod...

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In the dog, previous analyses of major histocompatibility complex (MHC) class I genes suggest a single polymorphic locus, Dog Leukocyte Antigen (DLA)-88. While 51 alleles have been reported, estimates of prevalence have not been made. We hypothesized that, within a breed, DLA-88 diversity would be restricted, and one or more dominant alleles could be identified. Accordingly, we determined allele usage in 47 Golden Retrievers and 39 Boxers. In each population, 10 alleles were found; 4 were shared. Seven novel alleles were identified. DLA-88*05101 and *50801 predominated in Golden Retrievers, while most Boxers carried *03401. In these breeds DLA-88 polymorphisms are limited and largely non-overlapping. The finding of highly prevalent alleles fulfills an important prerequisite for studying canine CD8+ T-cell responses.

Plexins are a family of genes (A,B,C, and D) that are expressed in many organ systems. Plexins expressed in the immune system have been implicated in cell movement and cell-cell interaction during the course of an immune response. In this study, the expression pattern of Plexin-B2 and Plexin-D1 in dendritic cells (DCs), which are central in immune activation, was investigated. Plexin-B2 and Plexin-D1 are reciprocally expressed in myeloid and plasmacytoid DC populations. Plasmacytoid DCs have high Plexin-B2 but low Plexin-D1, while the opposite is true of myeloid DCs. Expression of Plexin-B2 and Plexin-D1 is modulated upon activation of DCs by TLR ligands, TNFα, and anti-CD40, again in a reciprocal fashion. Semaphorin3E, a ligand for Plexin-D1 and Plexin-B2, is expressed by T cells, and interestingly, is dramatically higher on Th2 cells and on DCs. The expression of Plexins and their ligands on DCs and T cells suggest functional relevance. To explore this, we utilized chimeric mice lacking Plxnb2 or Plxnd1. Absence of Plexin-B2 and Plexin-D1 on DCs did not affect the ability of these cells to upregulate costimulatory molecules or the ability of these cells to activate antigen specific T cells. Additionally, Plexin-B2 and Plexin-D1 were dispensable for chemokine-directed in-vitro migration of DCs towards key DC chemokines, CXCL12 and CCL19. However, the absence of either Plexin-B2 or Plexin-D1 on DCs leads to constitutive expression of IL-12/IL-23p40. This is the first report to show an association between Plexin-B2 and Plexin-D1 with the negative regulation of IL-12/IL-23p40 in DCs. This work also shows the presence of Plexin-B2 and Plexin-D1 on mouse DC subpopulations, and indicates that these two proteins play a role in IL-12/IL-23p40 production that is likely to impact the immune response.