Detecting the antigen-specific B-cell-response to rabies vaccination.

Rationale: Rabies is a fatal disease, for which adequate pre- and post-exposure prophylaxis is available in the form of vaccination with inactivated virus. Serological testing (measuring titers of rabies-specific antibodies) is the conventional way to determine if someone is protected from rabies. Although cellular parameters might also contain valuable information in the prediction of protection against rabies, such parameters have never been studied in great detail.
The development of an assay which allows detection and quantification of antigen-specific immune cells and the description of their kinetics over time may open up many new possibilities, such as improved assessment of vaccine efficacy. Additionally, as rabies virus is a so-called neo-antigen, the magnitude and diversity of cellular responses to the vaccine can be used in the diagnosis and follow-up of patients with immune system disorders, particularly in case of suspected B-cell defects.
To develop such an antigen-specific assay, we need to have access to peripheral blood samples obtained from individuals with a relatively high frequency of rabies-specific immune cells, such as hyperimmunized volunteers who have received multiple consecutive rabies vaccinations.
Objective: This study is designed to develop a flow-cytometric assay that can detect rabies-specific B-cells generated in response to vaccination.
Study design: This is a cross-sectional study in which 10 hyperimmunized participants will be asked to donate a single sample of 53.5 ml blood (50 ml in EDTA tubes and 3.5 ml in a serum tube) and to complete a short questionnaire on their rabies vaccination history. The blood samples will be processed to isolate peripheral blood mononuclear cells which will either be used fresh, or be frozen for later use.The samples will be used to test and optimize the assay for detection of rabies antigen-specific cells.
Study population: Up to 10 healthy adult volunteers who have received multiple rabies vaccinations due to profession-related activities, which include potential contact with live rabies virus or related viruses. The control population consists of up to 10 healthy adult volunteers who have not been vaccinated against rabies.
Main study parameters/endpoints: Detection and quantification of rabies-specific B-cells.
Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The burden of the study is limited and related to a single donation of blood. Risks include local reactions to drawing of blood, such as local hematoma or pain.

We hypothesize that we are able to develop a flow-cytometric assay that is able to detect rabies-specific B-cells in the blood of hyperimmunized people.

Day 0. One single timepoint at one single visit, which is independent of the most recent rabies vaccination or the lack thereof.

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