A P. falciparum NF54 Reporter Line Expressing mCherry-Luciferase in Gametocytes, Sporozoites, and Liver-Stages

Abstract

Transgenic malaria parasites expressing fluorescent and bioluminescent proteins are valuable tools to interrogate malaria-parasite biology and to evaluate drugs and vaccines. Using CRISPR/Cas9 methodology a transgenic <i>Plasmodium falciparum</i> (Pf) NF54 line was generated that expresses a fusion of <i>mCherry</i> and <i>luciferase</i> genes under the control of the <i>Pf etramp10</i>.3 gene promoter (line mCherry-luc@etramp10.3). <i>Pf etramp10</i>.3 is related to rodent <i>Plasmodium uis4</i> and the <i>uis4</i> promoter has been used to drive high transgene expression in rodent parasite sporozoites and liver-stages. We examined transgene expression throughout the complete life cycle and compared this expression to transgenic lines expressing mCherry-luciferase and GFP-luciferase under control of the constitutive <i>gapdh</i> and <i>eef1a</i> promoters. The <i>mCherry-luc@etramp10.3</i> parasites express mCherry in gametocytes, sporozoites, and liver-stages. While no mCherry signal was detected in asexual blood-stage parasites above background levels, luciferase expression was detected in asexual blood-stages, as well as in gametocytes, sporozoites and liver-stages, with the highest levels of reporter expression detected in stage III-V gametocytes and in sporozoites. The expression of mCherry and luciferase in gametocytes and sporozoites makes this transgenic parasite line suitable to use in <i>in vitro</i> assays that examine the effect of transmission blocking inhibitors and to analyse gametocyte and sporozoite biology.