Publications (46) View all
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Article: Accessory Genes Confer High Replication Rate of Virulent Feline Immunodeficiency Virus (FIV).
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ABSTRACT: Feline immunodeficiency virus (FIV) is a lentivirus that causes AIDS in domestic cats, similar to HIV/AIDS in humans. FIV accessory protein Vif abrogates inhibition of infection by cat APOBEC3 restriction factors. FIV also encodes a multifunctional OrfA accessory protein, which has characteristics similar to HIV Tat, Vpu, Vpr, and Nef. To examine the role of vif and orfA accessory genes in FIV replication and pathogenicity, we generated chimeras between two FIV molecular clones with divergent disease potential: a highly pathogenic isolate that replicates rapidly in vitro and is associated with significant immunopathology in vivo, (FIV-C36, referred to as high virulence, or HV-FIV); and a less pathogenic strain (FIV-PPR, referred to as low virulence, or LV-FIV). Using PCR-driven overlap extension, we produced viruses in which vif, orfA or both genes from virulent HV-FIV replaced equivalent genes in LV-FIV. Generation of these chimeras is more straightforward in FIV than in primate lentiviruses, since FIV accessory gene open reading frames have very little overlap with other genes. All three chimeric viruses exhibited increased replication kinetics in vitro compared to LV-FIV. Chimeras containing HV-Vif or Vif/OrfA had replication rates equivalent to virulent HV-FIV parental virus. Furthermore, siRNA knockdown of feline APOBEC3 genes resulted in equalization of replication rates between LV-FIV and LV-FIV encoding HV-FIV Vif. These findings demonstrate that Vif-APOBEC interactions play a key role in controlling replication and pathogenicity of this immunodeficiency-inducing virus in its native host species, and that accessory genes act as mediators of lentiviral strain-specific virulence.Journal of Virology 05/2013; · 5.40 Impact Factor -
Article: Acute virulent infection with feline immunodeficiency virus (FIV) results in lymphomagenesis via an indirect mechanism.
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ABSTRACT: Four cats (24%) experimentally infected with FIV unexpectedly developed neoplastic changes within four months of inoculation. While FIV has previously been associated with neoplasia, the rapidity and high attack rate seen here is highly unusual. PCR for antigen receptor rearrangements (PARR) detected clonally rearranged T cells in two animals diagnosed with B cell follicular lymphoma by classical means. All cats were negative for feline leukemia virus; gamma-herpesvirus DNA was not amplified using degenerate primers. FIV proviral load in neoplastic tissue was two orders of magnitude lower than in the periphery, lower in neoplastic vs non-neoplastic lymph node, and clonal integration was not detected. We hypothesize that neoplasia was secondary to FIV immune dysregulation, and show that PARR can augment our capacity to phenotype these tumors and distinguish follicular hyperplasia from lymphoma. Age of exposure and relative virulence of the inoculum likely contributed to this unusual presentation of FIV infection.Virology 01/2013; · 3.35 Impact Factor -
Article: Zoonotic parasites of bobcats around human landscapes.
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ABSTRACT: We analyzed Lynx rufus fecal parasites from California and Colorado, hypothesizing that bobcats shed zoonotic parasites around human landscapes. Giardia duodenalis, Cryptosporidium, Ancylostoma, Uncinaria, and Toxocara cati were shed. Toxoplasma gondii serology demonstrated exposure. Giardia and Cryptosporidium shedding increased near large human populations. Genotyped Giardia may indicate indirect transmission with humans.Journal of clinical microbiology 06/2012; 50(9):3080-3. · 4.16 Impact Factor -
Article: Gene flow and pathogen transmission among bobcats (Lynx rufus) in a fragmented urban landscape.
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ABSTRACT: Urbanization can result in the fragmentation of once contiguous natural landscapes into a patchy habitat interspersed within a growing urban matrix. Animals living in fragmented landscapes often have reduced movement among habitat patches because of avoidance of intervening human development, which potentially leads to both reduced gene flow and pathogen transmission between patches. Mammalian carnivores with large home ranges, such as bobcats (Lynx rufus), may be particularly sensitive to habitat fragmentation. We performed genetic analyses on bobcats and their directly transmitted viral pathogen, feline immunodeficiency virus (FIV), to investigate the effects of urbanization on bobcat movement. We predicted that urban development, including major freeways, would limit bobcat movement and result in genetically structured host and pathogen populations. We analysed molecular markers from 106 bobcats and 19 FIV isolates from seropositive animals in urban southern California. Our findings indicate that reduced gene flow between two primary habitat patches has resulted in genetically distinct bobcat subpopulations separated by urban development including a major highway. However, the distribution of genetic diversity among FIV isolates determined through phylogenetic analyses indicates that pathogen genotypes are less spatially structured-exhibiting a more even distribution between habitat fragments. We conclude that the types of movement and contact sufficient for disease transmission occur with enough frequency to preclude structuring among the viral population, but that the bobcat population is structured owing to low levels of effective bobcat migration resulting in gene flow. We illustrate the utility in using multiple molecular markers that differentially detect movement and gene flow between subpopulations when assessing connectivity.Molecular Ecology 02/2012; 21(7):1617-31. · 5.52 Impact Factor -
Article: Microsphere immunoassay for the detection of cytokines in domestic cat (Felis catus) plasma: elevated IL-12/23 in acute feline immunodeficiency virus infections.
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ABSTRACT: We recently described the development and validation of a highly sensitive and specific microsphere immunoassay capable of simultaneously quantifying three domestic cat cytokines in tissue culture supernatant. Here we describe the modification of this assay to measure interferon gamma (IFNγ), interleukin (IL)-10 and IL-12/IL-23 p40 (IL-12/23) in domestic cat plasma, report values obtained from plasma collected after feline immunodeficiency virus (FIV) exposure, and compare plasma concentrations to blood cell mRNA expression. The validated quantitation limits of this assay are 31-1000 pg/ml for IFNγ, 63-2000 pg/ml for IL-10, and 20-625 pg/ml for IL-12/23. Plasma cytokine levels from domestic cats infected with pathogenic and/or apathogenic FIV were determined at 3-4 and 7-8 weeks post-infection. IL-12/23 was elevated (p<0.05) during acute infection with both FIV strains in two similar studies, conducted five years apart in different feline cohorts (n=44 total animals). IL-12/23 concentrations ranged from 377 to 1904 pg/ml in naïve cats and 552 to 3460 pg/ml in infected cats. In contrast, the majority of plasma samples had IFNγ and IL-10 concentrations below the lowest standard tested. The inability to consistently detect levels of IFNγ and IL-10 in plasma, despite the fact that mRNA changes were detected, suggests that these cytokines may be secreted and/or cleared in a more highly regulated manner than IL-12/23, or perhaps exert local effects under tighter peripheral constraints and/or at a lower effective concentration.Veterinary Immunology and Immunopathology 02/2012; 145(3-4):604-10. · 2.08 Impact Factor
