Browsing by Author "Schleupner, Charles J."

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    Deepening Our Understanding of COVID-19 Vaccine Decision-Making amongst Healthcare Workers in Southwest Virginia, USA Using Exploratory and Confirmatory Factor Analysis
    Bendetson, Jesse; Swann, Mandy C.; Lozano, Alicia; West, Jennifer; Hanlon, Alexandra L.; Crandell, Ian; Jatta, Maimuna; Schleupner, Charles J.; Baffoe-Bonnie, Anthony W. (MDPI, 2023-02-27)
    Vaccine hesitancy amongst healthcare workers (HCWs) has been a major challenge throughout the COVID-19 pandemic. While many studies have identified HCW characteristics and specific attitudes associated with COVID-19 vaccine hesitancy, researchers are still working towards developing a holistic understanding of the psychological constructs that influence COVID-19 vaccine decision-making in this population. Between 15 March and 29 March 2021, we distributed an online survey assessing individual characteristics and vaccine-related perceptions to employees of a not-for-profit healthcare system in Southwest Virginia (N = 2459). We then performed exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) to describe patterns of vaccine-related thought amongst HCWs and identify latent psychometric constructs involved in vaccine decision-making. The goodness of model fit was assessed using the Tucker–Lewis Index (TLI), the Comparative Fit Index (CFI), and the Root Mean Square Error of Approximation (RMSEA). Internal consistency and reliability of each factor were assessed using Cronbach’s alpha. EFA identified four latent psychometric constructs: Lack of trust in the COVID-19 vaccine; Anti-science sentiment; Adverse side-effects; and Situational risk assessment. The goodness of EFA model fit was adequate (TLI > 0.90, RMSEA ≤ 0.08) with acceptable internal consistency and reliability for three of four factors (Cronbach’s alpha > 0.70). The CFA model also had adequate goodness of fit (CFI > 0.90, RMSEA ≤ 0.08). We believe the psychometric constructs identified in this study can provide a useful framework for interventions to improve vaccine uptake amongst this critical population.
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    Determinants of Core Shell Dependent Rotavirus Polymerase Activity
    Steger, Courtney Long (Virginia Tech, 2019-02-22)
    Rotaviruses (RVs) are medically significant gastrointestinal pathogens and are a leading cause of childhood mortality in many countries. The RV RNA-dependent RNA polymerase, VP1, synthesizes RNA during viral replication only in the presence of another RV protein, VP2, which comprises the innermost core shell layer of the virion. Though these VP1-VP2 interactions are essential for RV replication, the mechanism by which the core shell regulates polymerase activity remains incompletely understood. Here, we sought to identify and characterize specific regions of both VP1 and VP2 that are required for core shell dependent polymerase activity. First, we used bioinformatics approaches to analyze VP1 and VP2 sequence diversity across many RV strains and identify positional locations of critical amino acid changes within the context of known structural domains and motifs. We next tested how the identified sequence differences influenced VP2-dependent VP1 activity in vitro. These data revealed that VP1 and VP2 protein diversity correlates with functional differences between avian and mammalian RV strains. Then, we used these sequential and functional incompatibilities to map key regions of VP1 important for mediating RNA synthesis. To pinpoint critical interacting regions of VP1 and VP2, we used site directed mutagenesis to engineer several modified VP1 and VP2 proteins. Then, we employed an in vitro RNA synthesis assay to test how the introduced mutations influenced VP2-dependent VP1 activity. Altogether, our results revealed several functionally important VP1 residues critical for in vitro VP2-dependent VP1 activity, either individually or in combination with neighboring residues, including E265/L267, R614, and D971/S978/I980. Structural analyses show VP2 interactions at these surface-exposed VP1 sites, which altogether supports a direct contact model of core shell dependent RV polymerase activity. Moreover, recombinant VP1 proteins containing multiple mutations at buried residues were incapable of facilitating RNA synthesis in vitro under the assay conditions, indicating that an extensive intramolecular signaling network exists to mediate VP1 activity. Taken together, these results suggest that VP2 binding at the VP1 surface may induce intramolecular interactions critical for VP1 activity. Overall, results from these studies provide important insight into VP1-VP2 binding interface(s) that are necessary for RV replication.
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    Ehrlichia chaffeensis-associated Hemophagocytic Lymphohistiocytosis: A Case Series and Literature Review
    Fazili, Tasaduz; Bansal, Ekta N.; Garner, Dorothy C.; Bajwa, Vijayendra; Kaur, Harpreet; Schleupner, Charles J. (American Journal of Medical Case Reports, 2021-08-17)
    Introduction: Hemophagocytic lymphohistiocytosis (HLH) is an uncommon condition characterized by abnormal, excessive immune activation resulting in severe cytopenias from an uncontrolled inflammatory response. It can be primary/ familial or secondary/sporadic. Infections, particularly viral infections are a common cause of secondary HLH. HLH due to Human monocytic ehrlichiosis (HME) is very rare, hence we are reporting our cases. Objective: To review cases of Ehrlichia-associated HLH at our institution and perform a literature review regarding this entity. Methods: We reviewed cases of Ehrlichia-associated HLH for the previous two years at our institution (Carilion Clinic). We then performed a review of the published literature on it, using Pubmed. Results: Over the past two years, five cases of Ehrlichia-associated HLH were diagnosed at our hospital. The average age of the patients was 67 years with predominantly males. All the patients were pancytopenic, and a majority had abnormal liver function tests. Diagnosis of ehrlichiosis was made by serum polymerase chain reaction (PCR) assay on blood. Patients had further testing done because of lack of clinical improvement. All patients had significantly elevated ferritin levels. Bone marrow biopsy samples of all patients showed findings of hemophagocytosis. All, but one, patients were treated with doxycycline and a combination of etoposide and dexamethasone. Three patients recovered while two died. On review of medical literature, we found a total of only 36 cases of Ehrlichia-associated HLH, including our five cases. There were 19 adults and 17 children. Both population groups showed varying degrees of pancytopenia. Splenomegaly was relatively uncommon, seen in less than one-third of the patients. Ferritin and triglyceride levels were routinely elevated. Bone marrow biopsy showing hemophagocytosis was the confirmatory test in all patients. A significant number of patients, both adults and children, required a combination of doxycycline and chemotherapy (etoposide and dexamethasone) to achieve clinical cure. Children had a better prognosis than adults, with one child and four adults succumbing to their illness. Conclusions: Ehrlichia-associated HLH is a rare but emerging disease entity. In endemic areas, a high degree of suspicion is required to diagnose ehrlichiosis and HLH resulting from it. Early diagnosis and prompt initiation of treatment for HLH is key to a favorable outcome.