title: Protective effect of different anti-rabies virus VHH constructs against rabies disease in mice.
abstract: Rabies virus causes lethal brain infection in about 61000 people per year. Each year, tens of thousands of people receive anti-rabies prophylaxis with plasma-derived immunoglobulins and vaccine soon after exposure. Anti-rabies immunoglobulins are however expensive and have limited availability. VHH are the smallest antigen-binding functional fragments of camelid heavy chain antibodies, also called Nanobodies. The therapeutic potential of anti-rabies VHH was examined in a mouse model using intranasal challenge with a lethal dose of rabies virus. Anti-rabies VHH were administered directly into the brain or systemically, by intraperitoneal injection, 24 hours after virus challenge. Anti-rabies VHH were able to significantly prolong survival or even completely rescue mice from disease. The therapeutic effect depended on the dose, affinity and brain and plasma half-life of the VHH construct. Increasing the affinity by combining two VHH with a glycine-serine linker into bivalent or biparatopic constructs, increased the neutralizing potency to the picomolar range. Upon direct intracerebral administration, a dose as low as 33 µg of the biparatopic Rab-E8/H7 was still able to establish an anti-rabies effect. The effect of systemic treatment was significantly improved by increasing the half-life of Rab-E8/H7 through linkage with a third VHH targeted against albumin. Intraperitoneal treatment with 1.5 mg (2505 IU, 1 ml) of anti-albumin Rab-E8/H7 prolonged the median survival time from 9 to 15 days and completely rescued 43% of mice. For comparison, intraperitoneal treatment with the highest available dose of human anti-rabies immunoglobulins (65 mg, 111 IU, 1 ml) only prolonged survival by 2 days, without rescue. Overall, the therapeutic benefit seemed well correlated with the time of brain exposure and the plasma half-life of the used VHH construct. These results, together with the ease-of-production and superior thermal stability, render anti-rabies VHH into valuable candidates for development of alternative post exposure treatment drugs against rabies.
authors.affiliation: National Reference Centre of Rabies, Viral Diseases, Scientific Institute of Public Health (WIV-ISP), Brussels, Belgium; Laboratory of Virology, Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: Sanne
authors.initials: S
authors.lastname: Terryn
authors.affiliation: National Reference Centre of Rabies, Viral Diseases, Scientific Institute of Public Health (WIV-ISP), Brussels, Belgium.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Francart
authors.affiliation: National Reference Centre of Rabies, Viral Diseases, Scientific Institute of Public Health (WIV-ISP), Brussels, Belgium.
authors.forename: Sophie
authors.initials: S
authors.lastname: Lamoral
authors.affiliation: Ablynx NV, Gent, Belgium.
authors.forename: Anna
authors.initials: A
authors.lastname: Hultberg
authors.affiliation: Ablynx NV, Gent, Belgium.
authors.forename: Heidi
authors.initials: H
authors.lastname: Rommelaere
authors.affiliation: Ablynx NV, Gent, Belgium.
authors.forename: Angela
authors.initials: A
authors.lastname: Wittelsberger
authors.affiliation: Ablynx NV, Gent, Belgium.
authors.forename: Filip
authors.initials: F
authors.lastname: Callewaert
authors.affiliation: Ablynx NV, Gent, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Stohr
authors.affiliation: Ablynx NV, Gent, Belgium.
authors.forename: Kris
authors.initials: K
authors.lastname: Meerschaert
authors.affiliation: Ablynx NV, Gent, Belgium.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Ottevaere
authors.affiliation: Ablynx NV, Gent, Belgium.
authors.forename: Catelijne
authors.initials: C
authors.lastname: Stortelers
authors.affiliation: Ablynx NV, Gent, Belgium.
authors.forename: Peter
authors.initials: P
authors.lastname: Vanlandschoot
authors.affiliation: National Reference Centre of Rabies, Viral Diseases, Scientific Institute of Public Health (WIV-ISP), Brussels, Belgium.
authors.forename: Michael
authors.initials: M
authors.lastname: Kalai
authors.affiliation: National Reference Centre of Rabies, Viral Diseases, Scientific Institute of Public Health (WIV-ISP), Brussels, Belgium; Laboratory of Virology, Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: Steven
authors.initials: S
authors.lastname: Van Gucht
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology; D002460:Cell Line; D004195:Disease Models, Animal; D005260:Female; D006207:Half-Life; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D051379:Mice; D011818:Rabies / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D011819:Rabies Vaccines / Q000276:immunology; D011820:Rabies virus / Q000235:genetics / Q000276:immunology*; D061905:Single-Domain Antibodies / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D014018:Tissue Distribution; D019562:Viral Load
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D007143:Immunoglobulin Heavy Chains; D011819:Rabies Vaccines; D061905:Single-Domain Antibodies