LABCG1 Affects Leishmania (Leishmania) Amazonensis Infectivity but Not Virulence or Sand Fly Infection

Leishmaniases are a complex spectrum of diseases caused by protozoan parasites of the genus Leishmania. Overall, they can be classified into two main clinical forms: tegumentary and visceral leishmaniasis (TL and VL, respectively). Our group has been studying LV79 and PH8 strains of Leishmania (Leishmania) amazonensis, one of the predominant TL-causing species in Brazil. PH8 is more infective in vitro and more virulent in vivo compared to LV79. Comparative proteomic analysis of promastigotes of both strains revealed that the ABCG1 transporter is 23.57-fold more abundant in PH8 than in LV79 strain. To determine whether L. (L.) amazonensis ABCG1 contributes to the higher virulence of PH8 strain, here we used a CRISPR-Cas9-based strategy to generate a knockout line for this gene. The mutants were compared to wild-type parasites regarding their growth, metacyclogenesis potential, LPG characteristics, resistance to complement-mediated lysis, infectivity in vitro, virulence in vivo, and ability to establish themselves in the sand fly vector. Overall, we demonstrate that while the loss of LABCG1 did not impact growth, metacyclogenesis, LPG characteristics, and resistance to complement-mediated lysis of Leishmania (Leishmania) amazonensis parasites, it did affect parasite infectivity in vitro, but not in vivo, both in the mouse model and in the sand fly vector. Therefore, these findings indicate that LABCG1 contributes to L. (L.) amazonensis infectivity but is not essential for parasite in vivo survival and virulence.