Abstract Cytomegalovirus (CMV) is a b-herpesvirus that is ubiquitously spread throughout the human population. CMV is the most common perinatal congenital viral infection among neonates and is also a common postnatal infection targeting immunocompromised hosts. CMV induced pneumonitis is among the most common manifestations of infection. Although an abundance of research has been conducted on the immune response to CMV, the true route of initial infection is still in contention. Through research with murine CMV (MCMV), it is thought that infection first occurs in the upper respiratory tract, specifically the olfactory epithelium, with a subsequent primary seeding of susceptible cells in the lung. Traditionally, experiments with MCMV have utilized systemic infection methods that may not accurately recapitulate in vivo dissemination. Therefore, re-examination with physiologically relevant viral infection methods are of the utmost importance. Following intratracheal administration of MCMV, I observed a distinct viral dissemination pattern with viral replication only occurring in the lung with later salivary gland colonization. This contrasted with intraperitoneal infection which resulted in robust infection of peripheral tissues, but no lung infection, with later colonization of the salivary gland. Preliminary data also suggests that following acute respiratory infection, there is an increase in the frequency of lymphocytes in the lung tissue with an outsized role of Natural Killer (NK) cells in response to pulmonary CMV as compared to other innate lymphoid cell (ILC) compartments. Based on these data, I hypothesize that the lung will play a central role in MCMV dissemination, and that ILCs will be heavily involved in preventing systemic viral dissemination. My first aim will seek to investigate in vivo viral kinetics following acute respiratory infection. I also aim to investigate the specific NK cell responses in the lung that control viral dissemination. My initial data suggests an important role for NK cell activation in the lung, with limited survival observed in animals deficient for Ly49H. To study the role of NK cells in response to respiratory MCMV infection, I propose to employ a variety of genetic manipulations to selectively remove NK cells, B and T cells, NK cell activating receptors, and cytokine receptors. Using these various models, I will assess animal survival, viral prevalence, and immune activation following acute respiratory MCMV infection. These proposed studies aim to elucidate the mechanisms of immune control of pulmonary CMV infection and may provide insights into cellular therapies for the treatment of CMV pneumonitis. Additionally, by studying a more physiologically relevant respiratory CMV infection model, I can gain further insights into the mechanisms of viral dissemination in the human pathogenesis of CMV. To prepare me for the proposed work, my training has taken place in the lab of the highly credentialed Laurent Br...