Development and evaluation of antiviral immunoglobulin single variable domains for prophylaxis of rabies in mice

Rabies virus causes an invariable fatal infectious disease in a large range of animals and humans. Yearly, rabies causes 59000 fatalities, mainly in developing countries. When people are exposed to the virus, disease can be prevented by treatment with a combination of vaccination and rabies immunoglobulins (RIG). RIG are purified from plasma of vaccinated persons or horses. Because RIG are scarce and expensive, they are often unavailable to those most in need. The WHO has therefore launched a call for the development of alternatives. In this thesis, it was investigated whether immunoglobulin single variable domains or VHH might serve as an alternative for RIG in rabies post-exposure prophylaxis. VHH are the antigen-binding fragments of heavy chain antibodies found in Camelidae. These small antibody fragments are easily produced in microbial expression systems and can easily be formatted in multimeric constructs. The general aim of this thesis was to develop and validate several types of anti-rabies VHH constructs for rabies prophylaxis in mice. It was investigated whether VHH can be used for the neutralization of the rabies virus and prevention of infection and disease in mice. We attempted to determine the advantages and limitations of VHH in this model and investigated a number of modifications that could be applied to improve the therapeutic efficacy of anti-rabies VHH