Multiple sclerosis is a neurodegenerative disorder affecting the central nervous system (CNS). Currently, the disease is incurable and immunomodulating drugs are the only option to control the disease. CD49d is an adhesion receptor expressed on most immune cells. Antibodies that bind to CD49d and block immune cells from trafficking toward the CNS are being pursued as one class of therapeutics. In this work, by combining recombinant antibody and phage display technologies we isolated 10 anti-CD49d single domain antibodies from a synthetic antibody light chain variable domain (VL) phage display library. Isolated VLs (~ 12 kDa) were expressed in Escherichia coli, purified and analysed for biophysical characteristics. The majority were expressed in good yields and were non-aggregating. All 10 VLs bound recombinant CD49d by ELISA, and 7 bound to CD49d-expressing cells in flow cytometry experiments. To empower the VLs for better therapeutic efficacy (thru increasing avidity and half-life), three of the lead VLs were re-engineered as fusions to fragment crystallisable (Fc) of human immunoglobulin gamma (IgG). The engineered hFc-VL fragments (~ 70 – 90 kDa) retained their specificity for CD49d by flow cytometry. With (i) being less immunogenic due to their human nature, (ii) their efficient access to cryptic epitopes (iii) having half-lives comparable to IgGs’ and (iv) being more cost effective compared to IgGs, these novel antibody fragments (monovalent VLs and bivalent hFc-VLs) provide a promising therapeutic platform against multiple sclerosis.

Multiple sclerosis is a neurodegenerative disorder affecting the central nervous system (CNS). Currently, the disease is incurable and immunomodulating drugs are the only option to control the disease. CD49d is an adhesion receptor expressed on most immune cells. Antibodies that bind to CD49d and block immune cells from trafficking toward the CNS are being pursued as one class of therapeutics. In this work, by combining recombinant antibody and phage display technologies we isolated 10 anti-CD49d single domain antibodies from a synthetic antibody light chain variable domain (VL) phage display library. Isolated VLs (~ 12 kDa) were expressed in Escherichia coli, purified and analysed for biophysical characteristics. The majority were expressed in good yields and were non-aggregating. All 10 VLs bound recombinant CD49d by ELISA, and 7 bound to CD49d-expressing cells in flow cytometry experiments. To empower the VLs for better therapeutic efficacy (thru increasing avidity and half-life), three of the lead VLs were re-engineered as fusions to fragment crystallisable (Fc) of human immunoglobulin gamma (IgG). The engineered hFc-VL fragments (~ 70 – 90 kDa) retained their specificity for CD49d by flow cytometry. With (i) being less immunogenic due to their human nature, (ii) their efficient access to cryptic epitopes (iii) having half-lives comparable to IgGs’ and (iv) being more cost effective compared to IgGs, these novel antibody fragments (monovalent VLs and bivalent hFc-VLs) provide a promising therapeutic platform against multiple sclerosis.

Multiple sclerosis is a neurodegenerative disorder affecting the central nervous system (CNS). Currently, the disease is incurable and immunomodulating drugs are the only option to control the disease. CD49d is an adhesion receptor expressed on most immune cells. Antibodies that bind to CD49d and block immune cells from trafficking toward the CNS are being pursued as one class of therapeutics. In this work, by combining recombinant antibody and phage display technologies we isolated 10 anti-CD49d single domain antibodies from a synthetic antibody light chain variable domain (VL) phage display library. Isolated VLs (~ 12 kDa) were expressed in Escherichia coli, purified and analysed for biophysical characteristics. The majority were expressed in good yields and were non-aggregating. All 10 VLs bound recombinant CD49d by ELISA, and 7 bound to CD49d-expressing cells in flow cytometry experiments. To empower the VLs for better therapeutic efficacy (thru increasing avidity and half-life), three of the lead VLs were re-engineered as fusions to fragment crystallisable (Fc) of human immunoglobulin gamma (IgG). The engineered hFc-VL fragments (~ 70 – 90 kDa) retained their specificity for CD49d by flow cytometry. With (i) being less immunogenic due to their human nature, (ii) their efficient access to cryptic epitopes (iii) having half-lives comparable to IgGs’ and (iv) being more cost effective compared to IgGs, these novel antibody fragments (monovalent VLs and bivalent hFc-VLs) provide a promising therapeutic platform against multiple sclerosis.