As well as altering the Fc portion of an antibody, the variable region of an immunoglobulin can be reformatted into a variety of different fragments such as Fab, F(ab)’2, scFv, VHH, and minibodies, or can be combined with a second specificity to make bispecific antibodies. The smaller antibody formats can be exploited for their improved tumour/tissue penetration and relative ease of expression in non-mammalian systems.
We can re-engineer antibodies and antibody fragments into virtually any format, some of which are shown below. Once produced, the antibodies can be characterised using an extensive suite of assays, such as ELISA, affinity determination using Biacore, or an appropriate biological assay.
F(ab)’2 retains the bivalent binding of an IgG without the Fc portion, that would otherwise be involved in the recruitment of effector functions through its interaction with Fcγ receptors.
Fabs are approximately a third of the size of a whole IgG and are monovalent. This smaller fragment has improved penetration into tissues and faster clearance from circulation, and can similarly benefit from the absence of Fcγ receptor-mediated effector functions. Fabs can easily be expressed in non-mammalian systems.
scFv are engineered by linking the variable domains of the heavy and light chains into a single chain molecule that is about a fifth of the size of a whole IgG. scFv are routinely used for phage display and can be expressed linked to a variety of fusion proteins for specific targeting.
VHH consist only of the variable domain of the heavy chain, and are about a tenth of the size of a whole IgG. Naturally found in camelids such as alpaca and llama, and also in sharks, VHH are highly stable and amenable to fusion with other proteins and can be linked to Fc domains to form heavy chain only antibodies.
Bispecific antibodies consists of two binding domains that target separate antigens, enabling two antigens to be bound simultaneously by one construct. This can be especially useful when directing an effector cell to a target cell. Bispecific antibodies or antibody fragments can be made in a variety of different formats and can be tailored to your requirements, depending upon application.
The above examples provide a sample of Abzena’s capabilities and we can re-engineer antibodies and antibody fragments into virtually any format. Once produced, the antibodies can be characterised using an extensive suite of binding assays (such as using ELISA), Affinity determination using Biacore Surface Plasmon Resonance or in an appropriate biological assay.
Working with Abzena
Abzena’s services are tailored for each project to ensure that the objectives are met or exceeded. Experienced project teams are assigned to each study focusing on progressing projects through to results in the minimum amount of time. Our clients widely regard us as professional and attentive partners who deliver quality results.
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