Galleria mellonella hemocytes: A novel phagocytic assay for Leishmania (Viannia) braziliensis

- A novel phagocytic assay for Leishmania (Viannia) braziliensis is proposed.
- Plasmatocytes and granular cells are the cell types interacting with this protozoan.
- Larvae immune cells possess a leishmanicidal activity.
- Improved capability of killing amastigotes is related to NO levels.

Galleria mellonella is an excellent invertebrate model for the study of diseases that involve interactions with cells from the innate immune system, since they have an innate immune system capable of recognizing the pathogens. Here we present for the first time, an alternative model for an in vitro phagocytic assay using hemocytes of G. mellonella larvae to study infection by Leishmania (Viannia) braziliensis. We showed that the insect phagocytic cells were able to engulf promastigotes. Furthermore, this infective form differentiated into the amastigote form inside those cells. However, the cells in this model seem resistant to the parasite, since amastigotes were depleted after 24 h and NO levels were maintained after infection. Our model opens an avenue of possibilities for new investigations regarding other Leishmania species, mechanisms of invasion and evasion, receptors involved, release of signaling molecules and, above all, it is a novel infection model using invertebrate animals.