Thesis advisor: Kenneth C. Williams / HIV infection elicits dysregulation of the immune system and is associated with a number of comorbidities. A common link among HIV-associated comorbidities is monocyte and macrophage activation, accumulation, and high turnover. Anti-retroviral therapy (ART), while useful in preventing HIV infection from progressing to immune dysfunction characterized by AIDS, does not eliminate infection. Even with ART, individuals retain a low level of virus that is able to reseed infection and a higher rate of comorbidities than uninfected people. Prior research has revealed an inflammatory monocyte/macrophage cell population that is uniquely in tissues with infection in an HIV model that uses simian immunodeficiency viral (SIV) infection of rhesus macaques. This cell type is characterized by expression of the inflammatory marker calprotectin. Through measurements of soluble calprotectin present in the plasma of SIV-infected rhesus macaques, I found that calprotectin levels remained low within the first two weeks of infection, sharply increased around three weeks post-infection, typically increased to a maximum during late stage chronic disease, and positively correlated with plasma viral load. Initial calprotectin levels suggests a trend that high pre-infection levels are associated with not progressing to AIDS or SIV encephalitis. Through immunostaining monocytes and flow cytometry, I found that calprotectin expression on classical, intermediate, and non-classical monocytes initially decreases with SIV infection, rebounds for most of infection, and sharply decreases again with late-stage chronic disease. Flow cytometry further showed that the calprotectin-expressing monocyte expresses CD163, CD169, and CCR2, but lacks expression for CX3CR1 and CCR5. Analysis of RNAseq data illustrates trends that suggest an increase in gene expression of genes involved in antiviral/antibacterial and chemotactic functions during conditions when calprotectin gene expression is also increasing. In summary, the data presented in this thesis suggest that the calprotectin-expressing monocyte/macrophage may come from an intermediate monocyte and play a role in inflammation through calprotectin secretion, activation, and increased chemotactic function. / Thesis (MS) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Biology.

Animal models have greatly contributed to the understanding of different aspects of human biology, as well as a variety of human-related pathogens and diseases. In order to study them, humanized mice susceptible to pathogens that replicate in human immune cells have been developed (e.g., humanized Rag2-/-γc-/- mice). These animals are engrafted with human hematopoietic stem cells (HSCs), resulting in the de novo development and maturation of the major functional components of the human adaptive immune system and the production of a variety of human cell types. Primary and secondary lymphoid organs in the mouse are populated with human cells, and animals have long term engraftment. These features make humanized mice an excellent in vivo model to study pathogenesis of human-specific viruses in the context of a human antiviral immune response. In addition, humanized mice have been shown to be useful preclinical models for the development and validation of antiviral therapeutics. In the present study, we aimed to successfully re-establish the humanized Rag2-/-γc-/- mouse model using cord blood-derived HSCs in our laboratory. We have shown that these mice sustain long term engraftment and systemic expansion of human cells, including the major targets of Kaposi's sarcoma Herpesvirus (KSHV) and Human immunodeficiency virus type 1 (HIV-1), in peripheral blood and different lymphoid organs. Further, we have begun to evaluate the susceptibility of the humanized Rag2-/-γc-/- mouse model to infection with KSHV. We demonstrate that human lymphocytes differentiated in reconstituted Rag2-/-γc-/- mice are permissive to KSHV infection ex vivo. This finding was corroborated by detection of KSHV mRNA expression in the spleen of a humanized mouse at 6 months post infection. In a different study, we tested the in vivo antiviral efficacy of a novel HIV-1 fusion inhibitor (PIE-12-trimer) in humanized Rag2-/-γc-/- mice. We have determined the half life of PIE-12-trimer in mouse plasma. Furthermore, the administration of PIE-12-trimer to HIV-1 infected humanized Rag2-/-γc-/- mice prevents depletion of CD4+ T cells in blood, thus it may be useful to prevent AIDS in human patients.