A novel inhibitory strategy of Leishmania major using Kluyveromyces lactis and Saccharomyces cerevisiae killer toxins

Leishmaniasis is a globally prevalent parasitic disease that has drawn significant attention. Killer yeasts offer a novel biological control method, presenting a potential alternative for treating leishmaniasis. This study evaluates the antileishmanial activity of Kluyveromyces lactis and Saccharomyces cerevisiae killer toxins against Leishmania major. Killer yeasts were isolated using the Well method. The genes encoding K2 and K.L killer toxins were identified by PCR, and the toxins were purified via SDS-PAGE. Antileishmanial and cytotoxic effects on L. major promastigotes and amastigotes were evaluated using the MTT assay. The first killer isolate was identified as Saccharomyces cerevisiae ZBAM (GenBank accession: OQ376749.1) and the second as Kluyveromyces lactis ZBAM (GenBank accession: OQ401036.1). IC50 values of K2 and K.L toxins against L. major promastigotes were significantly lower than Glucantime and Amphotericin B. The EC50 values at 24 hours for Glucantime, K2, and K.L were 11.83 ± 0.02 μg/ml, 2.35 ± 0.01 μg/ml, and 3.23 ± 0.03 μg/ml, respectively. The EC50 values for K2 and K.L against L. major amastigotes were also lower than Glucantime. This is the first report of the antileishmanial effects of K2 and K.L toxins against L. major, suggesting these yeasts as promising candidates for biological leishmaniasis treatment.