Abstract: One aspect of the present invention is a polypeptide having at least one bioactivity of a polypeptide p10 of a Borna Disease Virus. A second aspect of the present invention is a specific binding member, such as an antibody, that binds with at least a portion of a polypeptide p10 of a Borna Disease Virus. A third aspect of the present invention is a nucleic acid molecule that encodes a polypeptide having at least one bioactivity of a polypeptide p10 of a Borna Disease Virus. A fourth aspect of the present invention is a test kit that includes at least one of: a polypeptide of the present invention, a specific binding member of the present invention or a nucleic acid molecule of the present invention. A fifth aspect of the present invention is a vaccine and method of immunization that includes at least one of: a polypeptide of the present invention, a specific binding member of the present invention or a nucleic acid molecule of the present invention.