Protective effect of different anti-rabies virus VHH constructs against rabies disease in mice

PLoS One. 2014 Oct 27;9(10):e109367. doi: 10.1371/journal.pone.0109367. eCollection 2014.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Neutralizing / immunology
  • Antibodies, Viral / immunology
  • Cell Line
  • Disease Models, Animal
  • Female
  • Half-Life
  • Immunoglobulin Heavy Chains / genetics
  • Mice
  • Rabies / immunology*
  • Rabies / prevention & control
  • Rabies / virology
  • Rabies Vaccines / immunology
  • Rabies virus / genetics
  • Rabies virus / immunology*
  • Single-Domain Antibodies / administration & dosage
  • Single-Domain Antibodies / genetics
  • Single-Domain Antibodies / immunology*
  • Tissue Distribution
  • Viral Load

Substances

  • Antibodies, Neutralizing
  • Antibodies, Viral
  • Immunoglobulin Heavy Chains
  • Rabies Vaccines
  • Single-Domain Antibodies

Grant support

This work was supported by funds from the Research Foundation Flanders (FWO Vlaanderen, www.fwo.be), grant number G.0657.08, and the Interuniversity Attraction Poles Programme initiated by the Belgian Science Policy Office (BELSPO, www.belspo.be), grant number IUAP P7/32. Sanne Terryn received a fellowship from the WIV-ISP. The National Reference Centre of Rabies is partially supported by the Belgian Ministry of Social Affairs through a fund from the Health Insurance System (https://nrchm.wiv-isp.be/default.aspx). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.