Engineered Bovine Antibodies in the Development of Novel Therapeutics, Immunomodulators and Vaccines

Madhuri Koti,Ashish Sachan,Surinder Saini,Azad Kaushik

doi:10.3390/antib3020205

Madhuri Koti, Ashish Sachan + Show 2 more

Open Access

https://doi.org/10.3390/antib3020205

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Abstract

Some bovine antibodies across all classes are unique, such as the CDR3 of the variable heavy-domain (VH CDR3), which is exceptionally long (up to 66 amino acids), unlike most conventional antibodies where the VH CDR3 loops range from 10 to 25 amino acids. The exceptionally long VH CDR3 is encoded by unusually long germline IGHD genes together with insertion of novel “a” nucleotide rich conserved short nucleotide sequence (CSNS) specifically at the IGH V-D junction. Such an exceptionally long VH CDR3 confers unique “knob and stalk” structural architecture where the knob, formed by intra-VH CDR3 disulfide bridges, is separated by 20 Å solvent exposed stalk composed of anti-parallel beta strands. The substitution of the knob with cytokines, such as, erythropoietin and granulocyte colony stimulating factor 3 (granulocyte colony stimulating factor), results in expression of functional fusion proteins with enhanced pharmacokinetics. The beta stranded stalk can be substituted with other rigid structures, for example, repeat alpha helices to form coiled-coil that mimics the beta-stranded stalk and, thus, opens opportunities for insertion of this structure in the CDRs of antibodies across species. Given the versatility of such a structural platform in bovine antibody VH CDR3, it provides the opportunity for the development of new generation of diagnostics, therapeutics, vaccines and immunomodulating drugs.

Highlights

Two identical polypeptide chains of an immunoglobulin (IG), heavy (H)- and light (L)-chain, pair together and fold into domains where amino terminal comprises two antigen-binding sites of the same specificity [1]
In addition to known mechanisms of antibody diversification, generation of an exceptionally long (≥50–61 amino acids) complementarity-determining region 3 (CDR3) of the variable heavy-domain (VH CDR3) in some cattle antibodies provides a new mechanism of antibody diversification [5,6,7,8,9,10,11,12] that seems to compensate for limited genetic combinatorial diversity for acquisition of required functional antibodymediated humoral immunity
Such an exceptionally long VH CDR3, with multiple cysteines, expressed in 8%–10% of circulating bovine B cells [6], is the first to be documented for an antibody in a species

Summary

Introduction

Two identical polypeptide chains of an immunoglobulin (IG), heavy (H)- and light (L)-chain, pair together and fold into domains where amino terminal comprises two antigen-binding sites of the same specificity [1]. In addition to known mechanisms of antibody diversification (e.g., somatic hypermutations, junctional flexibility including N or P additions), generation of an exceptionally long (≥50–61 amino acids) complementarity-determining region 3 (CDR3) of the variable heavy-domain (VH CDR3) in some cattle antibodies provides a new mechanism of antibody diversification [5,6,7,8,9,10,11,12] that seems to compensate for limited genetic combinatorial diversity for acquisition of required functional antibodymediated humoral immunity Such an exceptionally long VH CDR3, with multiple cysteines, expressed in 8%–10% of circulating bovine B cells [6], is the first to be documented for an antibody in a species. Exceptionally long VH CDR3 offer opportunities for the development of new antibody-based diagnostics, immunomodulators, therapeutics and vaccines

Designing Antibody Fragments of Desired Function

Development of Bovine Antiviral Antibodies

Development of Immunomodulating Drugs and Vaccines

Conclusions and Future Directions