Induction and suppression of antiviral RNA silencing by Tomato spotted wilt virus

RNA silencing is an essential antiviral defense system in plants. Triggered by doublestranded RNA, silencing results in degradation or translational repression of target RNA. Viruses are inducers and targets of RNA silencing. To condition susceptibility, most plant viruses encode silencing suppressor proteins that interfere with RNA silencing. Tomato spotted wilt virus (TSWV) NSs protein is an RNA silencing suppressor. The mechanism of RNA silencing suppression by NSs and its role in virus infection and movement remain to be determined. We cloned NSs from the Hawaii isolate of TSWV. Using two independent assays, we show that NSs restored pathogenicity and supported the formation of local infection foci by suppressor-deficient Turnip mosaic virus (TuMV) and Turnip crinkle virus (TCV). Suppression of silencing directed against heterologous viruses establishes the foundation to determine the mechanism of antiviral RNA silencing suppression by NSs

Antiviral RNA silencing suppression activity of \u3ci\u3eTomato spotted wilt virus\u3c/i\u3e NSs protein

In addition to regulating gene expression, RNA silencing is an essential antiviral defense system in plants. Triggered by double-stranded RNA, silencing results in degradation or translational repression of target transcripts. Viruses are inducers and targets of RNA silencing. To condition susceptibility, most plant viruses encode silencing suppressors that interfere with this process, such as the Tomato spotted wilt virus (TSWV) NSs protein. The mechanism by which NSs suppresses RNA silencing and its role in viral infection and movement remain to be determined. We cloned NSs from the Hawaii isolate of TSWV and using two independent assays show for the first time that this protein restored pathogenicity and supported the formation of local infection foci by suppressor-deficient Turnip mosaic virus and Turnip crinkle virus. Demonstrating the suppression of RNA silencing directed against heterologous viruses establishes the foundation to determine the means used by NSs to block this antiviral process

Kinetics of Uropathogenic Escherichia coli Metapopulation Movement during Urinary Tract Infection

The urinary tract is one of the most frequent sites of bacterial infection in humans. Uropathogenic Escherichia coli (UPEC) strains are the leading cause of urinary tract infections (UTIs) and are responsible for greater than 80% of uncomplicated cases in adults. Infection of the urinary tract occurs in an ascending manner, with colonization of the bladder leading to possible kidney infection and bacteremia. The goal of this study was to examine the population dynamics of UPEC in vivo using a murine model of ascending UTI. To track individual UPEC lineages within a host, we constructed 10 isogenic clones of UPEC strain CFT073 by inserting unique signature tag sequences between the pstS and glmS genes at the attTn7 chromosomal site. Mice were transurethrally inoculated with a mixture containing equal numbers of unique clones. After 4 and 48 h, the tags present in the bladders, kidneys, and spleens of infected mice were enumerated using tag-specific primers and quantitative real-time PCR. The results indicated that kidney infection and bacteremia associated with UTI are most likely the result of multiple rounds of ascension and dissemination from motile UPEC subpopulations, with a distinct bottleneck existing between the kidney and bloodstream. The abundance of tagged lineages became more variable as infection progressed, especially after bacterial ascension to the upper urinary tract. Analysis of the population kinetics of UPEC during UTI revealed metapopulation dynamics, with lineages that constantly increased and decreased in abundance as they migrated from one organ to another

Bacteriophages with the Ability to Degrade Uropathogenic Escherichia Coli Biofilms

Escherichia coli-associated urinary tract infections (UTIs) are among the most common bacterial infections in humans. UTIs are usually managed with antibiotic therapy, but over the years, antibiotic-resistant strains of uropathogenic E. coli (UPEC) have emerged. The formation of biofilms further complicates the treatment of these infections by making them resistant to killing by the host immune system as well as by antibiotics. This has encouraged research into therapy using bacteriophages (phages) as a supplement or substitute for antibiotics. In this study we characterized 253 UPEC in terms of their biofilm-forming capabilities, serotype, and antimicrobial resistance. Three phages were then isolated (vB_EcoP_ACG-C91, vB_EcoM_ACG-C40 and vB_EcoS_ACG-M12) which were able to lyse 80.5% of a subset (42) of the UPEC strains able to form biofilms. Correlation was established between phage sensitivity and specific serotypes of the UPEC strains. The phages’ genome sequences were determined and resulted in classification of vB_EcoP_ACG-C91 as a SP6likevirus, vB_EcoM_ACG-C40 as a T4likevirus and vB_EcoS_ACG-M12 as T1likevirus. We assessed the ability of the three phages to eradicate the established biofilm of one of the UPEC strains used in the study. All phages significantly reduced the biofilm within 2–12 h of incubation

Detecting, Cloning, and Screening for Suppressors of RNA Silencing in \u3ci\u3eMaize Chlorotic Mottle Virus\u3c/i\u3e and \u3ci\u3eSugarcane Mosaic Virus\u3c/i\u3e

Maize lethal necrosis disease (MLND) is one of the most important viral diseases of maize. MLND occurs when Maize chlorotic mottle virus (MCMV) co-infects the same plant with one of several potyviruses, including Sugarcane mosaic virus, Wheat streak mosaic virus or Maize dwarf mosaic virus. Originally prevalent in the Midwest and Peru in the 1970s, the disease was called corn lethal necrosis (CLN) and was controlled through breeding and sanitation. Recently, the disease has re-emerged in East Africa and is rapidly spreading and threatening the food sources of subsistence-farming populations. This re-emergence has raised several questions about the unknown molecular mechanisms of MLND. RNA silencing is a prominent antiviral defense system in plants that may be involved in viral synergism. In single and double infections, MCMV and SCMV activate maize antiviral RNA silencing machinery, resulting in the accumulation of virus-derived small RNAs. Most plant viruses encode proteins called viral suppressors of RNA silencing (VSRs) to inactivate RNA silencing and overcome the host defense system. VSRs have been identified in several potyviruses but no silencing suppressor has been identified in MCMV. In this project, protocols to detect both SCMV and MCMV in plant tissue were established and optimized. A clone of the MCMV Nebraska isolate (MCMV-NE) and each open reading frame (ORF) of MCMV and SCMV were constructed for Agorbacterium infiltration. To identify silencing suppressors in MCMV and SCMV, individual proteins were cloned into binary vectors for transient expression in Nicotiana benthamiana and candidate proteins with silencing suppression activity have been identified. Identification and characterization of VSRs in MCMV and SCMV establishes the foundation to further study the molecular mechanisms involved in MLND. Advisor: Hernan Garcia-Rui

The Odd Couple: FINAL POSTER

The socio-political structure of Belgium, a whole containing disparate parts, serves as the catalyst for The Odd Couple: two individual secondary schools in Brussels, one Dutch-speaking, the other French-speaking, sharing the same site. The common element shared among the two schools is the public realm. Rather than shunning the public, the public is encouraged to actively engage in activities within the building. In this way the common spaces throughout the building take on the role of serving the needs and desires of both schools and the public, resulting in the necessity for dialogue and cooperation. By filtering program through a socio-political lens, a “school” typology emerges that emphasizes interaction and extramural learning.Sponsorship: Conger-Austin, Susa

The Odd Couple

The socio-political structure of Belgium, a whole containing disparate parts, serves as the catalyst for The Odd Couple: two individual secondary schools in Brussels, one Dutch-speaking, the other French-speaking, sharing the same site. The common element shared among the two schools is the public realm. Rather than shunning the public, the public is encouraged to actively engage in activities within the building. In this way the common spaces throughout the building take on the role of serving the needs and desires of both schools and the public, resulting in the necessity for dialogue and cooperation. By filtering program through a socio-political lens, a “school” typology emerges that emphasizes interaction and extramural learning.Sponsorship: Conger-Austin, Susa

The Odd Couple: FINAL SLIDESHOW

The socio-political structure of Belgium, a whole containing disparate parts, serves as the catalyst for The Odd Couple: two individual secondary schools in Brussels, one Dutch-speaking, the other French-speaking, sharing the same site. The common element shared among the two schools is the public realm. Rather than shunning the public, the public is encouraged to actively engage in activities within the building. In this way the common spaces throughout the building take on the role of serving the needs and desires of both schools and the public, resulting in the necessity for dialogue and cooperation. By filtering program through a socio-political lens, a “school” typology emerges that emphasizes interaction and extramural learning.Sponsorship: Conger-Austin, Susa