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Item Investigating Virus–Host Interactions in Cultured Primary Honey Bee Cells(MDPI AG, 2021-07) McMenamin, Alexander J.; Parekh, Fenali; Lawrence, Verena; Flenniken, Michelle L.Honey bee (Apis mellifera) health is impacted by viral infections at the colony, individual bee, and cellular levels. To investigate honey bee antiviral defense mechanisms at the cellular level we further developed the use of cultured primary cells, derived from either larvae or pupae, and demonstrated that these cells could be infected with a panel of viruses, including common honey bee infecting viruses (i.e., sacbrood virus (SBV) and deformed wing virus (DWV)) and an insect model virus, Flock House virus (FHV). Virus abundances were quantified over the course of infection. The production of infectious virions in cultured honey bee pupal cells was demonstrated by determining that naïve cells became infected after the transfer of deformed wing virus or Flock House virus from infected cell cultures. Initial characterization of the honey bee antiviral immune responses at the cellular level indicated that there were virus-specific responses, which included increased expression of bee antiviral protein-1 (GenBank: MF116383) in SBV-infected pupal cells and increased expression of argonaute-2 and dicer-like in FHV-infected hemocytes and pupal cells. Additional studies are required to further elucidate virus-specific honey bee antiviral defense mechanisms. The continued use of cultured primary honey bee cells for studies that involve multiple viruses will address this knowledge gap.Item Understanding resistance and transcriptional responses to potato virus Y infection in potato plants(Montana State University - Bozeman, College of Agriculture, 2021) Ross, Brian Thomas; Chairperson, Graduate Committee: Michelle Flenniken; Nina Zidack and Michelle L. Flenniken were co-authors of the article, 'Extreme resistance to viruses in potato and soybean' in the journal 'Frontiers in plant science' which is contained within this dissertation.; Nina Zidack and Michelle L. Flenniken were co-authors of the article, 'Transcriptional responses to potato virus Y infection in resistant and susceptible potato cultivars' submitted to the journal 'Cultivars' which is contained within this dissertation.The potato is one of the world's most important crops. Cultivation of potatoes occurs on every continent except Antarctica and in a wide variety of climates. Potatoes are susceptible to a multitude of pathogens that can decrease yield and market quality. Viruses are particularly problematic for potato growers, as most potato production involves the replanting of tubers grown the previous year. Because virus-infected potato plants can harbor virus in their tubers, these tubers can in turn be the source of infection in the next generation of plants. Strains of Potato virus Y are the most economically burdensome viruses for potato growers worldwide. In field settings, Potato virus Y is primarily transmitted to plant by aphids feeding on leaves, but PVY can also be transmitted mechanically through infected plant sap. The use of insecticides and the application of mineral oil to leaves can help limit aphid populations and prevent infection to an extent but are generally both less effective and more environmentally impactful than genetic antiviral resistance mechanisms. The incorporation of genes that provide durable resistance to Potato virus Y into commercial potatoes is a major focus of potato breeders. One form of resistance, called extreme resistance, is characterized by a lack of symptoms and little to no virus replication occurring at the site of infection, but the molecular mechanisms of this response are not well understood. A comprehensive analysis of the extreme resistance literature indicates that movement of the resistance protein from the cytoplasm to the nucleus of the cell directly after virus infection may be a key aspect of this immune response. The downstream, transcriptional aspects of the extreme resistance response are also not well understood. We analyzed the gene expression from a Potato virus Y-resistant potato variety, Payette Russet, and a commonly grown susceptible variety, Russet Burbank, at a series of time points after virus infection using RNA sequencing. Results of these analyses indicate that an immune response likely occurs in Payette Russet quickly after virus inoculation. These analyses also indicate that the virus-susceptible variety, Russet Burbank, exhibits changes in gene expression that are similar to other susceptible potato varieties during asymptomatic or tolerant infection. Furthering our understanding of the molecular mechanisms controlling resistance and severity of virus infections will help inform future breeding and genetic engineering efforts, which require detailed knowledge of the mechanisms of virus resistance.