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Browsing by Author "Gillam, Francis"

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    Designs of Antigen Structure and Composition for Improved Protein-Based Vaccine Efficacy
    Saylor, Kyle; Gillam, Francis; Lohneis, Taylor; Zhang, Chenming (2020-02-24)
    Today, vaccinologists have come to understand that the hallmark of any protective immune response is the antigen. However, it is not the whole antigen that dictates the immune response, but rather the various parts comprising the whole that are capable of influencing immunogenicity. Protein-based antigens hold particular importance within this structural approach to understanding immunity because, though different molecules can serve as antigens, only proteins are capable of inducing both cellular and humoral immunity. This fact, coupled with the versatility and customizability of proteins when considering vaccine design applications, makes protein-based vaccines (PBVs) one of today's most promising technologies for artificially inducing immunity. In this review, we follow the development of PBV technologies through time and discuss the antigen-specific receptors that are most critical to any immune response: pattern recognition receptors, B cell receptors, and T cell receptors. Knowledge of these receptors and their ligands has become exceptionally valuable in the field of vaccinology, where today it is possible to make drastic modifications to PBV structure, from primary to quaternary, in order to promote recognition of target epitopes, potentiate vaccine immunogenicity, and prevent antigen-associated complications. Additionally, these modifications have made it possible to control immune responses by modulating stability and targeting PBV to key immune cells. Consequently, careful consideration should be given to protein structure when designing PBVs in the future in order to potentiate PBV efficacy.
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    The impact of sphingosine kinase inhibitor-loaded nanoparticles on bioelectrical and biomechanical properties of cancer cells
    Babahosseini, Hesam; Srinivasaraghavan, Vaishnavi; Zhao, Zongmin; Gillam, Francis; Childress, Elizabeth; Strobl, Jeannine S.; Santos, Webster L.; Zhang, Chenming; Agah, Masoud (The Royal Society of Chemistry, 2015-11-19)
    Cancer progression and physiological changes within the cells are accompanied by alterations in the biophysical properties. Therefore, the cell biophysical properties can serve as promising markers for cancer detection and physiological activities. To aid in the investigation of the biophysical markers of cells, a microfluidic chip has been developed which consists of a constriction channel and embedded microelectrodes. Single-cell impedance magnitudes at four frequencies and entry and travel times are measured simultaneously during their transit through the constriction channel. This microchip provides a high-throughput, label-free, automated assay to identify biophysical signatures of malignant cells and monitor the therapeutic efficacy of drugs. Here, we monitored the dynamic cellular biophysical properties in response to sphingosine kinase inhibitors (SphKIs), and compared the effectiveness of drug delivery using poly lactic-co-glycolic acid (PLGA) nanoparticles (NPs) loaded with SphKIs versus conventional delivery. Cells treated with SphKIs showed significantly higher impedance magnitudes at all four frequencies. The bioelectrical parameters extracted using a model also revealed that the highly aggressive breast cells treated with SphKIs shifted electrically towards that of a less malignant phenotype; SphKI-treated cells exhibited an increase in cell-channel interface resistance and a significant decrease in specific membrane capacitance. Furthermore, SphKI-treated cells became slightly more deformable as measured by a decrease in their channel entry and travel times. We observed no significant difference in the bioelectrical changes produced by SphKI delivered conventionally or with NPs. However, NPs-packaged delivery of SphKI decreased the cell deformability. In summary, this study showed that while the bioelectrical properties of the cells were dominantly affected by SphKIs, the biomechanical properties were mainly changed by the NPs.
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    Vaccine Development Against Porcine Epidemic Diarrhea Virus Utilizing the Hepatitis B Virus Core Antigen Protein
    Gillam, Francis (Virginia Tech, 2018-01-11)
    Porcine epidemic diarrhea Virus (PEDV) is a virus effecting swine. It is the cause of disease that manifests with symptoms ranging from depression, to severe dehydration and death. Young piglets are particularly susceptible to the virus, which can reach mortality rates of 100%. Presence of the virus on a swine farm can therefore cause severe economic losses. Treatments currently exist for PEDV, but are mostly generated from the virus itself. There has recently been renewed interest in a vaccine that is made from a different source, which might help eliminate some of the side effects of those that currently exist on the market. This project outlines three experiments performed in animals. During the first experiment, a structural protein from the Hepatitis B virus was genetically altered to include important structural portions of PEDV. This new protein is generated in E. coli and purified. After purification, the protein assembles into a virus-like particle (VLP). VLPs are structural proteins of existing viruses that are expressed and assembled to mimic the virus. By doing so, the immune system recognizes the protein as a potential threat, and launches a response in the form of antibodies. Manipulations of the VLPs as describe herein allow the new vaccine to generate antibodies toward other diseases such as PEDV. Although all five of the vaccines used in the first experiment were able to generate appropriate antibodies, only two of them were effective at preventing PEDV from entering susceptible cells (virus neutralization). A second experiment, with three newly designed vaccines was therefore performed. This experiment, like the first, was successful in producing antibodies to several of the included PEDV protein sections, but none were able to neutralize the virus. These results led to a third experiment, during which further design improvements were made to the basic vaccine structure in an attempt to increase the neutralization capabilities of the vaccines. The results from the third experiment indicated that several changes to the vaccine increased the immune response to the structural portions of PEDV, providing a better overall vaccine candidate. This also led to the conclusion that one specific sequence from PEDV has a better ability to neutralize the virus than the other sections.