title: Description of a nanobody-based competitive immunoassay to detect tsetse fly exposure.
abstract: BACKGROUND
  Tsetse flies are the main vectors of human and animal African trypanosomes. The Tsal proteins in tsetse fly saliva were previously identified as suitable biomarkers of bite exposure. A new competitive assay was conceived based on nanobody (Nb) technology to ameliorate the detection of anti-Tsal antibodies in mammalian hosts.
  
  
  RESULTS
  A camelid-derived Nb library was generated against the Glossina morsitans morsitans sialome and exploited to select Tsal specific Nbs. One of the three identified Nb families (family III, TsalNb-05 and TsalNb-11) was found suitable for anti-Tsal antibody detection in a competitive ELISA format. The competitive ELISA was able to detect exposure to a broad range of tsetse species (G. morsitans morsitans, G. pallidipes, G. palpalis gambiensis and G. fuscipes) and did not cross-react with the other hematophagous insects (Stomoxys calcitrans and Tabanus yao). Using a collection of plasmas from tsetse-exposed pigs, the new test characteristics were compared with those of the previously described G. m. moristans and rTsal1 indirect ELISAs, revealing equally good specificities (> 95%) and positive predictive values (> 98%) but higher negative predictive values and hence increased sensitivity (> 95%) and accuracy (> 95%).
  
  
  CONCLUSIONS
  We have developed a highly accurate Nb-based competitive immunoassay to detect specific anti-Tsal antibodies induced by various tsetse fly species in a range of hosts. We propose that this competitive assay provides a simple serological indicator of tsetse fly presence without the requirement of test adaptation to the vertebrate host species. In addition, the use of monoclonal Nbs for antibody detection is innovative and could be applied to other tsetse fly salivary biomarkers in order to achieve a multi-target immunoprofiling of hosts. In addition, this approach could be broadened to other pathogenic organisms for which accurate serological diagnosis remains a bottleneck.
authors: Unit of Veterinary Protozoology, Department of Biomedical Sciences, Institute of Tropical Medicine Antwerp (ITM), Antwerp, Belgium; Unit of Cellular and Molecular Immunology, Vrije Universiteit Brussel (VUB), Brussels, Belgium; Laboratory of Myeloid Cell Immunology, VIB, Brussels, Belgium.
authors: Guy
authors: G
authors: Caljon
authors: Unit of Cellular and Molecular Immunology, Vrije Universiteit Brussel (VUB), Brussels, Belgium; Laboratory of Myeloid Cell Immunology, VIB, Brussels, Belgium.
authors: Shahid
authors: S
authors: Hussain
authors: Unit of Veterinary Protozoology, Department of Biomedical Sciences, Institute of Tropical Medicine Antwerp (ITM), Antwerp, Belgium.
authors: Lieve
authors: L
authors: Vermeiren
authors: Unit of Veterinary Protozoology, Department of Biomedical Sciences, Institute of Tropical Medicine Antwerp (ITM), Antwerp, Belgium; Laboratory of Zoophysiology, Department of Physiology, University of Ghent, Ghent, Belgium.
authors: Jan
authors: J
authors: Van Den Abbeele
mesh_terms: D000818:Animals; D000906:Antibodies / Q000032:analysis; D015415:Biomarkers / Q000097:blood; D002161:Camelids, New World / Q000276:immunology; D004781:Environmental Exposure; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007299:Insect Bites and Stings / Q000175:diagnosis*; D051379:Mice; D053758:Nanoparticles; D036103:Nanotechnology; D011817:Rabbits; D012463:Saliva / Q000276:immunology*; D012471:Salivary Proteins and Peptides / Q000032:analysis* / Q000276:immunology; D013552:Swine; D014345:Trypanosoma; D014352:Trypanosomiasis / Q000635:transmission*; D014370:Tsetse Flies / Q000276:immunology*
chemical_list: D000906:Antibodies; D015415:Biomarkers; D012471:Salivary Proteins and Peptides