Lactic Acid Supplementation Increases Quantity and Quality of Gametocytes in Plasmodium falciparum Culture

Abstract

Malaria infection by Plasmodium falciparum continues to afflict millions of people worldwide, with transmission dependent upon mosquito ingestion of the parasite gametocyte stage. These sexually committed stages develop from the asexual stages, yet the factors behind this transition are not completely understood. Here we find that lactic acid increases gametocyte quantity and quality in P. falciparum culture. Low passage NF54 parasites with varied time exposures of 8.2 mM lactic acid were monitored using blood film gametocyte counts and RNA analysis throughout two weeks of gametocyte development in vitro for a total of 5 biological cohorts. We found that daily continuous media exchange and 8.2 mM lactic acid supplementation increased gametocytemia by approximately 2- to 6-fold relative to controls after 5 days. In membrane feeding mosquito infection experiments, we found that gametocytes continuously exposed to 8.2 mM lactic acid supplementations were more infectious to Anopheles stephensi mosquitoes, essentially doubling prevalence of infected midguts and oocyst density. Supplementation on days 9-16 did not increase quantity of gametocytes, but did increase quality as measured by oocyst density by 2.4-fold. Lactic acid did not impact asexual growth as measured by blood film and luciferase quantification, as well as radioactive hypoxanthine incorporation assays. These data indicate a novel role for lactic acid in sexual development of the parasite.

The private life of malaria parasites: Strategies for sexual reproduction

“…[ 92 ], reviewed in [ 17 ]). Furthermore, conversion by P. falciparum is modulated by factors relating to state including density-dependent sensitivity to parasite-derived products, extracellular vesicles, spent medium, depletion of nutrients or RBCs, and the impact of drugs [ 12 , 52 , 77 , 87 , [93] , [94] , [95] , [96] , [97] , [98] , [99] ].…”

Protocols for Plasmodium gametocyte production in vitro: an integrative review and analysis

“…9: e60058 [ 42 ] 2020 West Lactic acid supplementation increases quantity and quality of gametocytes in Plasmodium falciparum culture Infect Immun. 89: e00635-20 [ 50 ] 2020 Llorà-Batlle Conditional expression of PfAP2-G for controlled massive sexual conversion in Plasmodium falciparum Sci Adv. 6:eaaz5057 [ 46 ] 2021 Wadi Investigation of factors affecting the production of P. falciparum gametocytes in an Indian isolate 3 Biotech.…”

“…Gametocytemia refers to the quantity of mature gametocytes produced, and some of the gametocytes in the studies were assessed for viability and infectivity (Table 2 ). Of the five protocols that used asynchronous culture, gametocytemia was between 2.5% and 4% [ 31 , 32 , 37 , 50 ]. Demanga et al [ 38 ] obtained a production of mature gametocytes of between 0.1% and 0.3% for both synchronous and asynchronous culture.…”

Histone lactylation: A new epigenetic axis for host-parasite signalling in malaria?

“…B) Increased conversion to sexual gametocytes (gametocytogenesis) is beneficial in promoting mosquito-borne transmission from stressed hosts. Gametocytogenesis is another virulence phenotype that was linked to lactate in a recent publication: when parasites were cultured in clinically-achievable levels of added lactate, they converted at a higher rate [12]. This conversion requires a suite of gametocyte-specific, epigenetically-controlled genes, including the Plasmodium -specific transcription factor AP2-G [13], a clear candidate for regulation via histone lactylation.…”