APPLYING THE NANOBODY TECHNOLOGY® TO TARGET THE BLOODSTREAM TRYPANOSOMAL TRANSFERRIN RECEPTOR

Kariuki, C. K. (Speaker)

Activity: Talk or presentationTalk or presentation at a conference

Description

INTRODUCTION: African trypanosomosis is a disease of medical and veterinary importance threatening both humans and animals in Sub-Saharan Africa. Currently, there are no anti-disease vaccines available and disease control relies heavily on the treatment with trypanocidal drugs. Therefore, targeting a trypanolytic/toxic molecule to a parasite surface molecule or receptor is ideal for increasing the drug targeting efficiency. In this study, we opted to use the trypanosomal transferrin receptor (TfR), a GPI-surface linked heterodimeric protein (ESAG6 and 7) bearing no similarity to the mammalian transferrin receptor involved in iron-uptake, as a target molecule. We propose to use a Nanobody technology® platform to generate and characterize Nanobodies® against the bloodstream trypanosomal transferrin receptor (ESAG6) as a tool to target trypanosomes.
METHODOLOGY: Following immunization of a llama with recombinant ESAG6 and selection against the ESAG6 via phage-display technology, three monovalent anti-ESAG6 Nanobodies® were selected. These were initially characterized in silico and after purification, via thermostability assays. The anti-ESAG6 Nanobodies® were subsequently tested in an Enzyme Linked Immunosorbent assay (ELISA) using whole cell lysate from different purified bloodstream-derived trypanosome species. In addition, Flow cytometry was performed with Alexa Fluor® 647 labelled anti-ESAG6 Nanobodies® on purified bloodstream-derived and blood-borne monomorphic trypanosomes.
RESULTS: The Nanobody® characterization assays revealed stable proteins with an expected molecular weight of 14 kDa and good thermal stability. ELISA assays indicated specific binding to T. brucei - derived lysate with little cross-reactivity to non - T. brucei related trypanosomal lysates. Flow cytometry analysis confirmed that one Alexa Fluor® 647 anti-ESAG6 Nanobody® could detect and bind to its antigen on intact monomorphic T. b. brucei Antat 1.1 parasites. In addition, a stronger signal was obtained on fixed and permeabilized parasites.
CONCLUSIONS: The available anti-ESAG6 Nanobodies® can bind their antigen in parasite lysate as well as on intact parasites. Moreover, binding of anti - ESAG6 Nanobodies® on fixed and permeabilized parasites indicate that the majority of TfR molecules are present intracellularly. Collectively, these results suggest that anti - TfR Nanobodies® might have diagnostic and therapeutic (targeting) potential.
Period5 May 2017
Held atAnnual scientific meeting of the Belgian Society of Parasitology and Protistology 5th May 2017 VUB, Etterbeek, Brussels, Belgium
Degree of RecognitionInternational