Master of Science (MS), Wright State University, 2023, Biological Sciences

The study was conducted to investigate the prevalence of four enteric viruses in mouse research facilities that may not be captured by routine pathogen screening. Fecal samples were collected from contact-sentinel mouse cages between April 2022 and January 2023, and screened for the presence of viral genome by RT-qPCR. Out of a total of 50 samples, murine norovirus and murine astrovirus were detected in two (4%) and one (2%) sample, respectively, while murine adenovirus and murine rotavirus were not detected. Furthermore, all samples were screened for the presence of infectious murine noroviruses and astroviruses using the RAW264.7 and Vero cells respectively. Interestingly, infectious murine norovirus was observed in ten (26.31%) samples and no infectious murine astrovirus. Using Sanger sequencing, the species of the detected norovirus was determined as murine norovirus type-1 (MNV-1). These findings highlight the need to update health monitoring practices in mouse research facilities and develop tools to monitor emerging viruses.

Committee: Abimbola O. Kolawole Ph.D. (Advisor); Athanasios Bubulya Ph.D. (Committee Member); Quan Zhong Ph.D. (Committee Member) Subjects: Biology

Master of Science (MS), Wright State University, 2024, Biological Sciences

Viruses with RNA genomes are prone to mutations during replication due to the inability of RNA polymerase to correct replication errors. This has enabled RNA viruses to develop resistance to antivirals including vaccines and neutralizing antibodies. Norovirus, a non- enveloped, positive-sense, single-stranded RNA virus, belongs to the Caliciviridae family. It has been reported that a single point mutation in virus capsid is enough to develop resistance to three neutralizing monoclonal antibodies A(mAbs) that were developed against MNV-1 (murine norovirus 1). Additionally, reports have shown in multiple viral species that antibody resistant viruses can protect antibody susceptible viruses of the same species from antibody neutralization by a process of clonal interference. Nevertheless, clonal Interference has never been reported in MNV. Therefore, I investigated the phenomenon of clonal interference in MNV. To do this, I mixed the susceptible (wild type MNV-1) and resistant (A382K mutant MNV-1) virus in different proportions before infecting RAW 264.7 cells with the virus mixture in the presence of neutralizing (mAb A6.2) or non-neutralizing (mAb 5C4) antibody for 5 passages. After every passage, I performed plaque assay, RNA extraction, RT-PCR, PAGE, and DNA sequencing to evaluate the percentage of protection the resistant virus offered the susceptible virus. My data suggested that there was no clonal Interference in murine norovirus.

Committee: Abimbola O. Kolawole Ph.D. (Advisor); Jeffrey L. Peters Ph.D. (Committee Member); Quan Zhong Ph.D. (Committee Member) Subjects: Biology

Master of Science, The Ohio State University, 2012, Food Science and Technology

Fresh produce is a high risk food for human norovirus (NoV) contamination, because it can easily become contaminated at both the pre- and post-harvest stages of cultivation. Disease surveillance has shown that human NoV is attributed to 40% of all fresh produce related outbreaks reported each year in the U.S. However, the ecology, persistence, and interaction of human NoV and fresh produce are all poorly understood. Increasing outbreaks of viruses in fresh and fresh-cut vegetables and fruits give high urgency to understanding the interaction of human NoV with fresh produce in order to develop effective preventive measures. In this research, the attachment, uptake, internalization, and dissemination of human NoV and its surrogates (murine norovirus, MNV-1; and Tulane virus, TV) were evaluated. First, the attachment of human NoV surrogates to fresh produce was visualized using confocal microscopy. Purified human NoV virus-like particles (VLPs), TV, and MNV-1 were conjugated with biotin, and subsequently applied to either Romaine lettuce or green onion. The biotinylated virus particles were visualized by incubation with streptavidin coated Quantum Dots (Q-Dots 655), which emit fluorescence that can be viewed using a confocal microscope. It was found that all three surrogates attached to the surface of Romaine lettuce leaves and were found aggregating in and around the stomata. Similarly, human NoV VLPs, TV, and MNV-1 were found to attach to the surface of Romaine lettuce roots. In the case of green onions, human NoV VLPs were found between the cells of the epidermis of both the shoots and roots. However, TV and MNV-1 were found to be covering the surface of the epidermal cells in both the shoots and roots of green onions. The results indicate that different viruses vary in their attachment patterns to different varieties of fresh produce. A quantitative assessment of the level of attachment of a human NoV GII.4 strain, TV, and MNV-1 was executed using Romaine lettuce a (open full item for complete abstract)

Committee: Jianrong Li PhD (Advisor); Ken Lee PhD (Committee Member); Yael Vodovotz PhD (Committee Member) Subjects: Food Science; Virology