Alpaca Single B Cell mAb Production

Alpacas naturally possess two types of antibodies: (i) classical tetrameric IgG antibodies assembled from two heavy chains and two light chains, and (ii) heavy‑chain antibodies (hcAbs) that naturally lack light chains and the CH1 domain of the heavy chain, forming a homodimeric structure consisting solely of two heavy chains linked by disulfide bonds. The variable domain of the heavy‑chain antibody is a structurally independent functional unit, designated as VHH—commonly referred to as a nanobody or single‑domain antibody (sdAb). Compared with conventional full‑length antibodies, alpaca‑derived antibodies—particularly VHH single‑domain antibodies—exhibit superior physicochemical stability, greater ease of genetic engineering, excellent antigen‑recognition specificity, and efficient recombinant expression in both prokaryotic and eukaryotic systems. Moreover, the amino acid sequence of VHH shares high homology with the human VH3 family of immunoglobulin heavy-chain variable regions, facilitating straightforward humanization, which has made them widely adopted in antibody drug development.

Single B cell antibody generation technology is a next-generation antibody discovery platform that has matured in recent years. Leveraging this technology platform, KMD Bioscience isolates lymphocytes from peripheral blood or immune lymphoid organs of immunized alpacas, and precisely enriches and sorts antigen‑specific single B lymphocytes via fluorescence-activated cell sorting (FACS). Depending on project requirements, we can perform single‑cell in vitro culture and assess antibody binding specificity by antigen-binding assays using culture supernatants. Subsequently, reverse transcription polymerase chain reaction (RT‑PCR) is performed with antibody‑specific primers to amplify the genes encoding the antibody variable regions. The target genes are directionally cloned into expression vectors, followed by recombinant antibody expression and purification in the expression system designated by the client. Finally, the purified products are validated for antigen‑binding activity via ELISA or other appropriate methods. With standardized workflows and a well‑established development platform, the alpaca‑derived monoclonal antibodies we deliver exhibit stable performance, and the overall project development success rate is consistently high.

Figure 1. A, Conventional IgG; B, Fab fragment of conventional antibody; C, Single-chain Fv (scFv) fragment of conventional antibody; D, Heavy-chain antibody or camelid antibody; E, VH domain of camelid antibody or single-domain antibody (sdAb)