The Role of Lipophosphoglycan in Leishmania mexicana parasite Infectivity of using Balb/c and C57 Macrophages model

Leishmania species are recognized to be pathogenic parasites that infect almost 15 million people globally, and up to date there is no vaccine available to stop the spread of Leishmania infection. For Leishmania mexicana to lose its virulence, the parasite culture must undergo in vitro passaging, little is known about the process underlying the reduction of parasite virulence. Thus, the purpose of this work was to look into the expression of lipophosphoglycan (LPG), as a virulence factor, during L. mexicana in vitro culturing and assessing the parasite's capacity to infect target cells. Results illustrated the extreme downregulation in LPG expression on the surface of promastigotes. Since anti-LPG monoclonal antibody staining showed LPG expression was significantly less expressed in passage 20 (P20) compared to its expression in passage 1 (P1). In addition, this was confirmed by flow cytometry analysis, which also showed that LPG was highly expressed in P1 compared to P20. Moreover, an in vitro infectivity assay was performed using Balb/c and C57 macrophages. Both cells were infected with L. mexicana promastigotes from P1 and P20 for 24 hours. The results illustrated the ability of P1, but not P20, to transform into the non-flagellated amastigotes sage inside infected cells. Our results concluded the significant role of LPG protein in L. mexicana virulence and its ability to induce infection.