Arbovirus phenotype alters transmission potential

Extrinsic and environmental factors are known to affect the transmission of arthropod-borne viruses (arboviruses), including variations in the arthropod vector populations. Differences among these factors have been associated with differential transmission and are sometimes used to control the spread of an arbovirus through a vertebrate population in an effort to prevent or disrupt an outbreak. However, diversity in intrinsic viral populations, such as genetic and phenotypic variability, is not often accounted for when considering alterations in transmission. Presented in this dissertation are four experimental studies that explore the contribution of viral intrinsic factors, especially phenotypic variability, to the transmission potential of arboviruses as judged by modeling parameters such as vectorial capacity (VC) and the basic reproductive number (R0). The overall hypothesis of this research is that phenotypic differences of arboviruses alter the transmission potential of these arboviruses by conferring fitness advantages in either the vector or the vertebrate. Further, these phenotypic differences need not be large in magnitude to affect the relative transmission potential. To investigate this hypothesis, this research determined 1) whether intrinsic viral characteristics can lead to differential transmission in a given locale, 2) whether variability of viral fitness in the mosquito vector can lead to significant differential transmission potential, 3) how our newly formulated methods from our preceding aim could aid in the explanation of a currently puzzling phenomenon in the field of arbovirology, 4) whether phenotypic differences in the vertebrate host alters the potential for transmission, and 5) how identified phenotypic differences in both the vector and vertebrate hosts could act synergistically or antagonistically to alter transmission potential of arboviruses. The research in this dissertation offers a more accurate tool for assessing transmission potential in the vector, provides a new model assessing transmission potential in the vertebrate, and provides several of the necessary steps towards a more appropriate calculation of R0. Our use of R0 based on dynamic phenotypic differences provides a framework for a more dynamic formulation of transmission models, and provides an accessible framework for output validation and reporting to public health stakeholders

A Review and Outlook for the Removal of Radon-Generated Po-210 Surface Contamination

The next generation low-background detectors operating deep underground aim for unprecedented low levels of radioactive backgrounds. The deposition and presence of radon progeny on detector surfaces is an added source of energetic background events. In addition to limiting the detector material's radon exposure in order to reduce potential surface backgrounds, it is just as important to clean surfaces to remove inevitable contamination. Such studies of radon progeny removal have generally found that a form of etching is effective at removing some of the progeny (Bi and Pb), however more aggressive techniques, including electropolishing, have been shown to effectively remove the Po atoms. In the absence of an aggressive etch, a significant fraction of the Po atoms are believed to either remain behind within the surface or redeposit from the etching solution back onto the surface. We explore the chemical nature of the aqueous Po ions and the effect of the oxidation state of Po to maximize the Po ions remaining in the etching solution of contaminated Cu surfaces. We present a review of the previous studies of surface radon progeny removal and our findings on the role of oxidizing agents and a cell potential in the preparation of a clean etching technique.Comment: Proceedings of the Low Radioactivity Techniques (LRT) 2017, Seoul, South Korea, May 24-26, 201

A Method for Repeated, Longitudinal Sampling of Individual Aedes aegypti for Transmission Potential of Arboviruses

Mosquito-borne viruses are the cause of significant morbidity and mortality worldwide, especially in low- and middle-income countries. Assessing risk for viral transmission often involves characterization of the vector competence of vector–virus pairings. The most common determination of vector competence uses discreet, terminal time points, which cannot be used to investigate variation in transmission aspects, such as biting behavior, over time. Here, we present a novel method to longitudinally measure individual biting behavior and Zika virus (ZIKV) transmission. Individual mosquitoes were exposed to ZIKV, and from 9 to 24 days post-exposure, individuals were each offered a 180 μL bloodmeal every other day. Biting behavior was observed and characterized as either active probing, feeding, or no bite. The bloodmeal was then collected, spun down, serum collected, and tested for ZIKV RNA via qRT-PCR to determine individuals’ vector competence over time. This included whether transmission to the bloodmeal was successful and the titer of expectorated virus. Additionally, serum was inoculated onto Vero cells in order to determine infectiousness of positive recovered sera. Results demonstrate heterogeneity in not only biting patterns but expectorated viral titers among individual mosquitoes over time. These findings demonstrate that the act of transmission is a complex process governed by mosquito behavior and mosquito–virus interaction, and herein we offer a method to investigate this phenomenon

Key Resources for Creating Online Nutrition Education for Those Participating in Supplemental Nutrition Assistance Program Education

Internet-based nutrition education is becoming an important tool in serving the rural, low-income community, yet the task of creating such programming can be daunting. The authors describe the key resources used in developing an Internet-based nutrition education program for those participating in Supplemental Nutrition Assistance Program Education. Extension program providers wanting to create an online program may benefit from becoming familiar with the resources and ideas described in this article

Credit Card Usage of College Students: Evidence from Louisiana State University (Research Information Sheet #107)

In recent years, there has been a dramatic growth in credit card usage among college students. How are Louisiana State University undergraduates using credit cards? Are LSU students managing credit card debt wisely? What can LSU do to offer the appropriate kinds of help to enable students to be financially literate? These are the issues addressed in this publication.https://digitalcommons.lsu.edu/agcenter_researchinfosheets/1007/thumbnail.jp

Fe and O EELS Studies of Ion Irradiated Murchison CM2 Carbonaceous Chondrite Matrix

Introduction: The physical and chemical response of hydrated carbonaceous chondrite materials to space weathering processes is poorly understood. Improving this understanding is a key part of establishing how regoliths on primitive carbonaceous asteroids respond to space weathering processes, knowledge that supports future sample return missions (Hayabusa 2 and OSIRISREx) that are targeting objects of this type. We previously reported on He+ irradiation of Murchison matrix and showed that the irradiation resulted in amorphization of the matrix phyllosilicates, loss of OH, and surface vesiculation. Here, we report electron energy-loss spectroscopy (EELS) measurements of the irradiated material with emphasis on the Fe and O speciation. Sample and Methods: A polished thin section of the Murchison CM2 carbonaceous chondrite was irradiated with 4 kilovolts He(+) (normal incidence) to a total dose of 1 x 10(exp 18) He(+) per square centimeter. We extracted thin sections from both irradiated and unirradiated regions in matrix using focused ion beam (FIB) techniques with electron beam deposition for the protective carbon strap to minimize surface damage artifacts from the FIB milling. The FIB sections were analyzed using a JEOL 2500SE scanning and transmission electron microscope (STEM) equipped with a Gatan Tridiem imaging filter. EELS spectra were collected from 50 nanometer diameter regions with an energy resolution of 0.7 electronvolts FWHM at the zero loss. EELS spectra were collected at low electron doses to minimize possible artifacts from electron-beam irradiation damage. Results and Discussion: Fe L (sub 2,3) EELS spectra from matrix phyllosilicates in CM chondrites show mixed Fe(2+)/Fe(3+) oxidation states with Fe(3+)/Sigma Fe approximately 0.5. Fe L(sub 2,3) spectra from the irradiated/ amorphized matrix phyllosilicates show higher Fe(2+)/Fe(3+) ratios compared to spectra obtained from pristine material at depths beyond the implantation/amorphization layer. We also obtained O Ka spectra from phyllosilicates in both regions of the sample. The O Ka spectra show a pre-edge feature at approximately 530.5 electronvolts that is related to O 2p states hybridized with Fe 3d states. The intensity ratio of the O Ka pre-edge peak relative to the main part of the O Ka edge (that results from transitions of O 1s to 2p states) is lower in the irradiated layer compared to the pristine material and may reflect the loss of O (as OH) as was observed by IR spectroscopy. Conclusions: In addition to amorphization and OH loss, EELS spectra of He(+) irradiated matrix phyllosilicates in Murchison show that some of the Fe(3+) is reduced to Fe(2+). Spectral deconvolution is underway to extract quantitative ratios from the EELS spectra

Identifying the coiled-coil triple helix structure of β-peptide nanofibers at atomic resolution

Peptide self-assembly represents a powerful bottom-up approach to the fabrication of new nanomaterials. β3-peptides are non-natural peptides composed entirely of β-amino acids, which have an extra methylene in the backbone and we reported the first fibers derived from the self-assembly of β3-peptides that adopt unique 14-helical structures. β3-peptide assemblies represent a class of stable nanomaterials that can be used to generate bio- and magneto-responsive materials with proteolytic stability. However, the three-dimensional structure of many of these materials remains unknown. In order to develop structure-based criteria for the design of new β3-peptide-based biomaterials with tailored function, we investigated the structure of a tri-β3-peptide nanoassembly by molecular dynamics simulations and X-ray fiber diffraction analysis. Diffraction data was collected from aligned fibrils formed by Ac-β3[LIA] in water and used to inform and validate the model structure. Models with threefold radial symmetry resulted in stable fibers with a triple-helical coiled-coil motif and measurable helical pitch and periodicity. The fiber models revealed a hydrophobic core and twist along the fiber axis arising from a maximization of contacts between hydrophobic groups of adjacent tripeptides on the solvent-exposed fiber surface. These atomic structures of macro-scale fibers derived from β3-peptide-based materials provide valuable insight into the effects of the geometric placement of the side-chains and the influence of solvent on the core fiber structure which is perpetuated in the superstructure morphology