Exploring the presence of Leishmania RNA Virus 1 in Leishmania (Viannia) braziliensis isolates from the most endemic area of American tegumentary Leishmaniasis in Argentina.

American Tegumentary Leishmaniasis (ATL) comprises a group of diseases caused by protozoan parasites of the Leishmania genus. The endosymbiont Leishmania RNA Virus 1 (LRV1) has been associated with severe disease forms and treatment failure in several South American countries; however, no data are available for Argentina. This study conducted the first screening for LRV1 in the country's most endemic region, Salta Province, analyzing 44 clinical samples from cutaneous, mucosal, and relapsing ATL cases. All samples were identified as Leishmania (Viannia) braziliensis by PCR-RFLP, and tested negative for LRV1 using RT-PCR. Applying a zero-patient design to avoid concluding absolute absence, the theoretical LRV1 prevalence was estimated to be below 7 %, substantially lower than the 25-77 % range reported in Amazonian regions. These findings suggest that LRV1 distribution may not extend into Argentina. While LRV1 may contribute to disease severity when present, it should not be regarded as an exclusive or definitive factor in clinical presentation or therapeutic response in the region. Further research into genetic, immunological, and epidemiological factors is needed to better understand severe ATL forms in Argentina and to develop targeted strategies for improved disease management.