Delivery of a functional anti-trypanosome Nanobody in different tsetse fly tissues via a bacterial symbiont, Sodalis glossinidius.
BACKGROUND
Sodalis glossinidius, a vertically transmitted microbial symbiont of the tsetse fly, is currently considered as a potential delivery system for anti-trypanosomal components that reduce or eliminate the capability of the tsetse fly host to transmit parasitic trypanosomes, an approach also known as paratransgenesis. An essential step in developing paratransgenic tsetse is the stable colonization of adult flies and their progeny with recombinant Sodalis bacteria, expressing trypanocidal effector molecules in tissues where the parasite resides.


RESULTS
In this study, Sodalis was tested for its ability to deliver functional anti-trypanosome nanobodies (Nbs) in Glossina morsitans morsitans. We characterized the in vitro and in vivo stability of recombinant Sodalis (recSodalis) expressing a potent trypanolytic nanobody, i.e. Nb_An46. We show that recSodalis is competitive with WT Sodalis in in vivo conditions and that tsetse flies transiently cleared of their endogenous WT Sodalis population can be successfully repopulated with recSodalis at high densities. In addition, vertical transmission to the offspring was observed. Finally, we demonstrated that recSodalis expressed significant levels (ng range) of functional Nb_An46 in different tsetse fly tissues, including the midgut where an important developmental stage of the trypanosome parasite occurs.


CONCLUSIONS
We demonstrated the proof-of-concept that the Sodalis symbiont can be genetically engineered to express and release significant amounts of functional anti-trypanosome Nbs in different tissues of the tsetse fly. The application of this innovative concept of using pathogen-targeting nanobodies delivered by insect symbiotic bacteria could be extended to other vector-pathogen systems.
Department of Biomedical Sciences, Unit of Veterinary Protozoology, Institute of Tropical Medicine Antwerp (ITM), Antwerp, Belgium. ldevooght@itg.be.
Linda
L
De Vooght
Department of Biomedical Sciences, Unit of Veterinary Protozoology, Institute of Tropical Medicine Antwerp (ITM), Antwerp, Belgium. gcaljon@itg.be.|Unit of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium. gcaljon@itg.be.|Laboratory of Myeloid Cell Immunology, VIB, Brussels, Belgium. gcaljon@itg.be.
Guy
G
Caljon
Department of Biomedical Sciences, Unit of Veterinary Protozoology, Institute of Tropical Medicine Antwerp (ITM), Antwerp, Belgium. kderidder@itg.be.
Karin
K
De Ridder
Department of Biomedical Sciences, Unit of Veterinary Protozoology, Institute of Tropical Medicine Antwerp (ITM), Antwerp, Belgium. jvdabbeele@itg.be.|Department of Physiology, Laboratory of Zoophysiology, University of Ghent, B-9000, Ghent, Belgium. jvdabbeele@itg.be.
Jan
J
Van Den Abbeele
D000818:Animals; D000913:Antibodies, Protozoan / Q000096:biosynthesis* / Q000235:genetics; D004755:Enterobacteriaceae / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D007303:Insect Vectors / Q000382:microbiology*; D061905:Single-Domain Antibodies / Q000096:biosynthesis* / Q000235:genetics; D013559:Symbiosis; D014345:Trypanosoma; D014370:Tsetse Flies / Q000382:microbiology*
D000913:Antibodies, Protozoan; D061905:Single-Domain Antibodies