Project Summary Candidate and career development: Dr. Ayana Morales is an Infectious Diseases physician committed to translational research in the field of HIV associated malignancies to uncover virus and host mechanisms of disease, with a specific focus on host interactions with Kaposi sarcoma herpesvirus in the context of HIV co- infection. Her overarching goal is to become an independent physician scientist investigating the questions of virus and host interaction to ultimately discover novel biomarkers and safer and improved treatments. In the short term, her goals are: 1. To expand her technical skills in virology, immunology, and pathology; 2. To gain experience in the use of bioinformatics; 3. Gain additional grant and manuscript writing skills; 4. To successfully compete for a K08 award to support her transition to a career as an independent researcher. Research: The research plan is proposed as a supplement to the R01 (PQ6) New Models of KSHV Oncogenesis and KS Immune Environment, active through 2025 (PI Dr. Ethel Cesarman). It builds upon Dr. Morales' findings that a proto-oncogene, Wilms' tumor 1 (WT1) is highly expressed in Kaposi sarcoma, and is significantly higher in KS lesions in people living with HIV/AIDS. Dr. Morales seeks to investigate the role of WT1 in KS and whether HIV contributes to WT1-mediated effects. Specifically, she will characterize the spatial relationship of WT1 to the KS immune tumor microenvironment (TME) and study the role of WT1 in 2D and 3D models and its immunomodulatory impacts to test the hypothesis that WT1 promotes immune evasion in KS by impacting immune cell trafficking and function, which are further compromised in the presence of HIV infection. This will be achieved through the following specific aims: 1) Characterize the spatial relationship of WT1-expressing cells to the KS immune TME, and 2) Investigate the role of WT1 in KSHV infected endothelial cells in vitro using 2D and 3D culture models to determine cell-intrinsic effects that can have immunomodulatory consequences. Significance: Our studies will dissect the spatial relationship of WT1 in the immune contexture of KS and the role of WT1 within 2D and 3D models of KS, which may provide a clearer understanding of the tumor immune microenvironment and hence lead to novel clinical strategies to recondition the TME against KS.