Publications by authors named "Kaycie Hopkins"

The range of the mosquito Aedes aegypti continues to expand, putting more than two billion people at risk of arboviral infection. The sterile insect technique (SIT) has been used to successfully combat agricultural pests at large scale, but not mosquitoes, mainly because of challenges with consistent production and distribution of high-quality male mosquitoes. We describe automated processes to rear and release millions of competitive, sterile male Wolbachia-infected mosquitoes, and use of these males in a large-scale suppression trial in Fresno County, California.

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RNA degradation is tightly regulated to selectively target aberrant RNAs, including viral RNA, but this regulation is incompletely understood. Through RNAi screening in Drosophila cells, we identified the 3'-to-5' RNA exosome and two components of the exosome cofactor TRAMP (Trf4/5-Air1/2-Mtr4 polyadenylation) complex, dMtr4 and dZcchc7, as antiviral against a panel of RNA viruses. We extended our studies to human orthologs and found that the exosome as well as TRAMP components hMTR4 and hZCCHC7 are antiviral.

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The four dengue virus serotypes (DENV1 to DENV4) are mosquito-borne flaviviruses that cause up to ~100 million cases of dengue annually worldwide. Severe disease is thought to result from immunopathogenic processes involving serotype cross-reactive antibodies and T cells that together induce vasoactive cytokines, causing vascular leakage that leads to shock. However, no viral proteins have been directly implicated in triggering endothelial permeability, which results in vascular leakage.

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Viruses must gain entry into cells to establish infection. In general, viruses enter either at the plasma membrane or from intracellular endosomal compartments. Viruses that use endosomal pathways are dependent on the cellular factors that control this process; however, these genes have proven to be essential for endogenous cargo uptake, and thus are of limited value for therapeutic intervention.

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The mosquito-transmitted bunyavirus, Rift Valley fever virus (RVFV), is a highly successful pathogen for which there are no vaccines or therapeutics. Translational arrest is a common antiviral strategy used by hosts. In response, RVFV inhibits two well-known antiviral pathways that attenuate translation during infection, PKR and type I IFN signaling.

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In response to infection, the innate immune system rapidly activates an elaborate and tightly orchestrated gene expression program to induce critical antimicrobial genes. While many key players in this program have been identified in disparate biological systems, it is clear that there are additional uncharacterized mechanisms at play. Our previous studies revealed that a rapidly-induced antiviral gene expression program is active against disparate human arthropod-borne viruses in Drosophila.

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Alphaviruses are a large class of insect-borne human pathogens and little is known about the host-factor requirements for infection. To identify such factors, we performed a genome-wide RNAi screen using model Drosophila cells and validated 94 genes that impacted infection of Sindbis virus (SINV), the prototypical alphavirus. We identified a conserved role for SEC61A and valosin-containing protein (VCP) in facilitating SINV entry in insects and mammals.

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A unique facet of arthropod-borne virus (arbovirus) infection is that the pathogens are orally acquired by an insect vector during the taking of a blood meal, which directly links nutrient acquisition and pathogen challenge. We show that the nutrient responsive ERK pathway is both induced by and restricts disparate arboviruses in Drosophila intestines, providing insight into the molecular determinants of the antiviral "midgut barrier." Wild-type flies are refractory to oral infection by arboviruses, including Sindbis virus and vesicular stomatitis virus, but this innate restriction can be overcome chemically by oral administration of an ERK pathway inhibitor or genetically via the specific loss of ERK in Drosophila intestinal epithelial cells.

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Bunyaviruses are an emerging group of medically important viruses, many of which are transmitted from insects to mammals. To identify host factors that impact infection, we performed a genome-wide RNAi screen in Drosophila and identified 131 genes that impacted infection of the mosquito-transmitted bunyavirus Rift Valley fever virus (RVFV). Dcp2, the catalytic component of the mRNA decapping machinery, and two decapping activators, DDX6 and LSM7, were antiviral against disparate bunyaviruses in both insect cells and adult flies.

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Although c-FLIP has been identified as an important player in the extrinsic (death receptor-induced) apoptosis pathway, its endogenous function in mature T lymphocytes remains undefined. c-FLIP may inhibit or promote T cell death as previous data demonstrate that the c-FLIP(L) isoform can promote or inhibit caspase 8 activation while the c-FLIP(S) isoform promotes or inhibits T cell death when overexpressed. Although the c-FLIP(R) isoform inhibits cell death in cell lines, its function in T cells remains unknown.

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Although the long isoform of cellular FLIP (c-FLIP(L)) has been implicated in TCR-mediated signaling, its role in T cell proliferation remains controversial. Some studies have demonstrated that overexpression of c-FLIP(L) promotes T cell proliferation and NF-kappaB activation, whereas others have reported that c-FLIP(L) overexpression has no effect or even inhibits T cell proliferation. To establish the role of c-FLIP(L) in T lymphocyte proliferation, we have generated a conditional knockout mouse strain specifically lacking c-FLIP(L) in T lymphocytes.

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