Immunogenic carrier molecule

Davio et al. (43) report efforts to obtain monoclonal antibodies (mAbs) to STX. Because STX is a small molecule of approximately 300 daltons, well below the size necessary for immunogenicity, a carrier molecule must be conjugated to the hapten (STX). This technique must minimize alterations of the antigenic form. For the anti-STX antibodies tested to date, the ratios of immunoassay response factor to pharmacological potency for various STX derivatives differ substantially, the immunoassay being virtually unresponsive to some of the common natural derivatives (44). 

Carrier Molecule Hapten Hapten-carrier Immunogen... 

Several plant vims coat proteins, including those of TMV, CPMV, AlMV and Tomato bushy stunt vims (TBSV), have been used to produce and deliver antigenic determinants from a variety of viral and bacterial pathogens. These data have been summarized in numerous publications and several reviews [12,13]. The ease of virus purification coupled with enhanced peptide immunogenicity when fused to carrier molecules makes this approach very attractive for vaccine development. 

The final application of the antibody must be borne in mind when deciding the extent of characterization. Initially, the antibody must be tested to establish whether binding occurs with the immunogen, with and without any carrier molecules used in the immunization. This test should be carried out with reference to the intended application to control for bridge binding. For instance, a reagent intended for use in a capture ELISA should be tested when coated onto the assay solid phase. If the antibody is intended for in vivo immunoneutralization, it should be tested initially in a liquid phase assay. If the final use is to be immunocytochemical, then the testing should be conducted on tissue sections. 

To become immunogenic, a hapten has to be linked with a large molecule, such as a protein, prior to its introduction into the host animal. Several proteins can act as such carrier molecules including bovine serum albumin, human serum albumin, ovalbumin, thyroglobulin, poly-L-lysine, and hemocyanin. Among these proteins, bovine serum albumin is most commonly used because it is inexpensive, readily available, very soluble, highly immunogenic, and, in addition, resists denaturatlon (3). 

The ratio of the hapten to the carrier molecules is also very important for the success of an immunochemical assay. Too few or too many hapten molecules linked to a carrier molecule will inevitably lead to poor immunogenicity. Desirable ratios of hapten to carrier molecules are in the range 10-100 1 (3). 

The first carrier molecules used for immunogen conjugation were proteins. A foreign protein administered in vivo by any one of a number of potential routes nearly ensured... 

A wide variety of novel approaches for the development of mucosal immune responses by administration of antigens in different delivery systems have been investigated, in many cases, with considerable success. These approaches include (1) the coadministration of immunogens with adjuvants active at the mucosal surface, (2) the coupling of immunogens to carrier molecules that promote their uptake at the mucosal inductive site, and (3) the expression of antigens in live attenuated bacterial or viral vectors, which can promote the colonization of mucosal tissue and the incorporation of antigens into a variety of microparticulate and adhesive vehicles, which are taken up in mucosal inductive sites. 

Conjugate Antigen/antigen derivative or antibody covalently coupled to a label (= tracer) or hapten coupled to a carrier protein molecule (= immunogen)... 

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