The type I interferon-inducible factor tetherin retains virus particles on the surfaces of cells infected with vpu-deficient human immunodeficiency virus type 1 (HIV-1). While this mechanism inhibits cell-free viral spread, the immunological implications of tethered virus have not been investigated. We found that surface tetherin expression increased the antibody opsonization of vpudeficient HIV-infected cells. The absence of Vpu also stimulated NK cell-activating Fc␥RIIIa signaling and enhanced NK cell degranulation and NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC). The deletion of vpu in HIV-1-infected primary CD4؉ T cells enhanced the levels of antibody binding and Fc receptor signaling mediated by HIV-positive-patient-derived antibodies. The magnitudes of antibody binding and Fc signaling were both highly correlated to the levels of tetherin on the surfaces of infected primary CD4 T cells. The affinity of antibody binding to Fc␥RIIIa was also found to be critical in mediating efficient Fc activation. These studies implicate Vpu antagonism of tetherin as an ADCC evasion mechanism that prevents antibody-mediated clearance of virally infected cells. IMPORTANCEThe ability of the HIV-1 accessory factor to antagonize tetherin has been considered to primarily function by limiting the spread of virus by preventing the release of cell-free virus. This study supports the hypothesis that a major function of Vpu is to decrease the recognition of infected cells by anti-HIV antibodies at the cell surface, thereby reducing recognition by antibody-dependent clearance by natural killer cells.

This work describes the immobilization of beta-galactosidase onto polyelectrolyte multilayer assemblies of the polyanion poly[1-[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) and the polycation poly(ethylenimine) (PEI) constructed by electrostatic self-assembly (ESA). A single layer of beta-galactosidase was deposited over a precursor film comprising up to five bilayers of the PEI/PAZO polyelectrolyte pair. The enzyme was deposited on both the polycationic (PEI) and the polyanionic (PAZO) surfaces. Quartz crystal microbalance with dissipation monitoring (QCM-D), single-wavelength ellipsometry, and UV-visible absorption spectroscopy revealed differences in both the amount of beta-galactosidase incorporated in each of the multilayer assemblies and the resulting enzyme packing density in the films. The enzymatic films were immersed in a reaction solution containing o-nitrophenyl-beta-d-galactopyranoside (ONPG), and absorbance measurements were used to monitor the concentration of o-nitrophenyl (ONP), the product of the beta-galactosidase catalyzed by hydrolysis of ONPG. Although our data indicate that comparable amounts of beta-galactosidase are incorporated onto both surfaces, enzymatic activity is substantially inhibited when the beta-galactosidase is immobilized on the polyanionic surface compared to the enzyme on the polycationic surface. The difference in catalytic activities reflects the different abilities of the two polyelectrolytes to screen the protein's active site from the substrate environment. In both assemblies, the protein interpenetrated the PEI/PAZO multilayer, disrupting the J-aggregated state of the PAZO chromophores. This work demonstrates that the charge, conformation, and composition of underlying polyelectrolyte cushions have a significant effect on the structure and function of an immobilized protein within functional nanoassemblies.

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Previous studies have found that commercial human pregnancy tests are often too insensitive to function to their advertised >99% accuracy. Improper orientation of proteins used for recognition of ligands in sensors can often prevent the binding site from being available to the ligand, thereby decreasing sensor sensitivity. We have developed a simple method for the immobilization of anti‐human chorionic gonadotropin on a sensor surface that maximizes its sensitivity by ensuring ligand binding sites are exposed and densely packed. This surface also has an improved regenerative capacity over previously reported human chorionic gonadotropin sensors, retaining 99% of initial sensitivity after six regeneration cycles with 8M urea. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 2012.

Context: Despite equal enrollment proportions in MD and PhD programs, there are fewer women than men in MD-PhD programs and academic medicine. Factors important in degree program selection, including the perception of gender disparities, among undergraduate students were characterized. Methods: In 2017, women pre-health students at four public North Carolina universities were invited to participate in an online survey regarding career plans, decision factors, and perceptions of gender disparities in MD, PhD and MD-PhD pathways. This study characterizes factors important to program selection, and evaluates the association of intended graduate program with perceived gender disparities using Fisher’s exact tests. Results: Among the n=186 female survey participants, most were white (54 %) and intended MD, PhD, and/or MD-PhD programs (52 %). Sixty percent had heard of MD-PhD programs, over half had no research experience, and half were considering but uncertain about pursuing a research career. The most common factors influencing degree program choice were perceived competitiveness as an applicant, desired future work environment, and desire for patient interaction. Twenty-five percent of students considering MD, PhD, and MD-PhD programs stated that perceived gender disparities during training for those degrees will influence their choice of program, however intended degree was not statistically associated with perceived gender disparities. Discussion: Perceived gender disparities may influence choice of graduate training program but are not among the top factors. Perceived competitiveness as an applicant is an important career consideration among undergraduate women. Strategies to increase awareness of MD-PhD programs, to encourage women to consider all training paths for which they are qualified are needed. What is known: Though men and women are nearly equally represented in MD-only and PhD-only programs, women are underrepresented in MD-PhD programs, which train physician-scientists. Prior studies have shown gender is not associated with rates of attrition from MD-PhD programs or differences in academic preparation, research interest, or research experience, suggesting enrollment differences by gender may be due to fewer women applying to MD-PhD programs. Gender parity in the physician-scientist workforce is critical to equitably serving a diverse patient population. What this study adds: This study is the first to examine the role of gender disparities in the career choices of undergraduate women. Given the moderate familiarity with MD-PhD training and lack of research experience among respondents, increased awareness of MD-PhD programs and expanded research opportunities may help undergraduates make informed career choices. This may increase women MD-PhD applicants, creating a more balanced physician-scientist workforce to address the needs of patients from all backgrounds. Keywords: Education, Graduate, Sexism, Career Choice, Biomedical Research/education, Female