Induction of immune responses and molecular cloning of the heavy chain antibody repertoire of Lama glama

Functional heavy chain immunoglobulins have, so far, only been found in cam els and llamas. Antigen-specific fragments of these heavy chain IgGs (V-HH) are of great interest in biotechnology because they are very stable and ca n be produced at high level by the yeast Saccharomyces cerevisiae. The work described in this paper was conducted to determine whether llamas (Lama gl ama) are a practical source of antigen-specific V-HH fragments. Llamas were immunised with various types of antigens and the antibody responses were e xamined during the course of immunisation. Both, conventional and heavy cha in IgG antibodies were produced in response to each of the antigens. The he avy chain IgG repertoire displayed a recognition pattern different to that of conventional llama IgGs, resulting in the expansion of the accessible ep itope repertoire. Llamas have a lower proportion of heavy chain IgG antibod ies in their serum than have camels. To enable the specific and efficient i solation of V-HH genes from peripheral blood B-cells, the long and short-hi nge sequences of Lama glama heavy chain IgGs were determined, revealing the presence of a novel subclass of short-hinge heavy chain IgG. Long and shor t-hinge specific PCR primers were designed to be used in the construction o f llama V-HH libraries. We conclude that, using the techniques described, a ntigen-specific V-HH antibody fragments are readily accessible from the lla ma, thus providing highly valuable binding molecules for a variety of appli cations. (C) 2000 Elsevier Science B.V. All rights reserved.