Leishmania RNA virus ile enfekte Leishmania major eksozomlarinin karakterizasyonu ve L. major enfeksyonunda sitosolik DNA algıılama ile alakalı yolakların etkisinin değerlendirilmesi

Leishmaniasis is a neglected infectious disease caused by Leishmania parasite. The disease represents a significant health problem, necessitating urgent development of effective treatment strategies. New World Leishmania species harboring Leishmania RNA virus (LRV) cause severe, metastatic disease. In this thesis, we compared LRV2-1 deficient and proficient Old World L. major strains in terms of their exosomal content and infectivity. PCR and mass spectrometry based analysis revealed that virus infected Leishmania exosomes contained at least 64% of the viral RNA but not the viral proteins. LRV2-1 positive and negative L. major strains had similar infectivity in macrophages, the positive strain exhibited delayed infection in a cutaneous leishmaniasis model in mice. Next, we aimed to investigate the role of cGAS-STING DNA sensing pathway in Leishmania infection. Infection rates in STING and TBK-1 knockout cell lines were significantly lower than wild type THP-1 cells and this difference was related to decreased phagocytic capacities of the knockout lines. Effect of the TBK1 inhibitor amlexanox was investigated in in vitro and in vivo infection models. The drug blocked parasite phagocytosis in macrophages and delayed footpad swelling in parasite infected mice, suggesting that amlexanox could be of interest as a candidate drug in cutaneous leishmaniasis treatment. We also aimed to determine the role of ISG15 in L. major infection and autophagy by mutating the ISG15 using a LentiCRISPRv2 system. Our findings revealed a pro-parasitic role of ISG15 in early stages of Leishmania infection. Furthermore, we found that autophagy was enhanced in ISG15 KO cells, suggesting a regulatory role for ISG15 in autophagy. Collectively, our findings might benefit future work related to Leishmania immunity in defining new targets and developing effective treatment strategies.