Comparative histopathological and immunological analysis of LRV2-positive and LRV2-negative Leishmania tropica in a BALB/c mouse cutaneous leishmaniasis model.

Leishmaniasis is a vector-borne disease endemic in more than 99 countries and manifests primarily as cutaneous, mucocutaneous, or visceral forms. This study aimed to assess the impact of Leishmania RNA virus 2 (LRV2) on immune responses and disease pathology in mice infected with Leishmania tropica. BALB/c mice were inoculated subcutaneously in the right hind footpad with L. tropica either lacking or carrying LRV2 (LRV2- and LRV2 + groups, respectively) and monitored for 24 weeks. Footpad and liver tissues were collected post-sacrifice, and parasite presence was determined using microscopy, culture, and molecular methods. Biomarkers of inflammation (IL-6, TNF-α, and TGF-β1), oxidative stress (iNOS and eNOS), and apoptosis (Caspase 3) were analyzed by immunohistochemistry and qPCR. Leukocyte infiltration was observed in footpad lesions of both LRV2- and LRV2 + groups; however, lesion sizes did not differ significantly between them. In footpad tissues, TNF-α, TGF-β1, eNOS, and Caspase 3 expression levels were significantly higher in both experimental groups compared to controls. In liver tissues, IL-6 and eNOS expression was significantly elevated in both experimental groups relative to controls, while TNF-α expression was notably higher in the LRV2 + group. Furthermore, both footpad and liver tissues from LRV2 + mice showed increased eNOS and iNOS expression compared to LRV2- mice. Overall, these findings indicate that the presence of LRV2 does not significantly influence inflammatory cytokine production or apoptosis in footpad and liver tissues, but it markedly enhances oxidative stress in both.