**4. Future perspectives of the development of recombinant antibodies**

This chapter is focused on fully human therapeutic mAbs, mainly those derived from phage display technologies. Other technologies emerged in recent years for the obtainment of human mAbs with high promises of success, derived directly from human B lymphocytes by two main approaches, immortalization of memory B cells by polyclonal stimulation followed by EBV transformation and/or the capture and sorting of memory B cells or plasmablasts followed by amplification of the mAb variable chains expressed by the single B cell, which can be transfected to mammalian cells [27]. The natural pairing of rearranged heavy chain and light chains regions can be found only in B cells. Display technologies add complexity to the repertoire by pairing light and heavy chains by chance. A very promising new class of antibodies consists of single domain antibodies from camels and sharks comprising only one variable domain of the heavy chain [146, 147]. These molecules are stable, non-aggregating molecules both *in vitro* and *in vivo*. Carrying the ability to bind antigens intracellularly as intrabodies inside the nucleus or cytosol makes them an important platform for antigen trafficking and knockdown, meaning a promise for the future [38].

**References**

2014;**32**(1):32-39

Suppl 1):21-27

**321**(6069):522-525

[1] Aggarwal RS. What's fueling the biotech engine-2012 to 2013. Nature Biotechnology.

Display Technologies for the Selection of Monoclonal Antibodies for Clinical Use

http://dx.doi.org/10.5772/intechopen.70930

63

[3] Kohler G, Milstein C. Continuous cultures of fused cells secreting antibody of predefined

[4] Norman DJ, Shield CF3rd, Barry J, Henell K, Funnell MB, Lemon J. A U.S. clinical study of Orthoclone OKT3 in renal transplantation. Transplantation Proceedings. 1987;**19**(2

[5] Hwang WY, Foote J. Immunogenicity of engineered antibodies. Methods. 2005;**36**(1):3-10 [6] Almagro JC, Fransson J. Humanization of antibodies. Frontiers in Bioscience: A Journal

[7] Morrison SL, Johnson MJ, Herzenberg LA, Oi VT. Chimeric human antibody molecules: Mouse antigen-binding domains with human constant region domains. Proceedings of the National Academy of Sciences of the United States of America. 1984;**81**(21):6851-6855

[8] Jones PT, Dear PH, Foote J, Neuberger MS, Winter G. Replacing the complementarity-determining regions in a human antibody with those from a mouse. Nature. 1986;

[9] Verhoeyen M, Milstein C, Winter G. Reshaping human antibodies: Grafting an antilyso-

[10] Riechmann L, Clark M, Waldmann H, Winter G. Reshaping human antibodies for ther-

[11] Queen C, Schneider WP, Selick HE, Payne PW, Landolfi NF, Duncan JF, et al. A humanized antibody that binds to the interleukin 2 receptor. Proceedings of the National

[12] Caldas C, Coelho V, Kalil J, Moro AM, Maranhão AQ, Brı́gido MM. Humanization of the anti-CD18 antibody 6.7: An unexpected effect of a framework residue in binding to

[13] Tsurushita N, Hinton PR, Kumar S. Design of humanized antibodies: From anti-Tac to

[14] Lopes dos Santos M, Yeda FP, Tsuruta LR, Horta BB, Pimenta Jr AA, Degaki TL, et al. Rebmab200, a humanized monoclonal antibody targeting the sodium phosphate transporter NaPi2b displays strong immune mediated cytotoxicity against cancer: A novel

[15] Lindegren S, Andrade LN, Back T, Machado CM, Horta BB, Buchpiguel C, et al. Binding affinity, specificity and comparative biodistribution of the parental murine monoclonal

reagent for targeted antibody therapy of cancer. PLoS One. 2013;**8**(7):e70332.

Academy of Sciences of the United States of America. 1989;**86**(24):10029-10033

[2] Reichert JM. Antibodies to watch in 2017. MAbs. 2017;**9**(2):167-181

specificity. Nature. 1975;**256**(5517):495-497

and Virtual Library. 2008;**13**:1619-1633

zyme activity. Science. 1988;**239**(4847):1534-1536

antigen. Molecular Immunology. 2003;**39**(15):941-952

apy. Nature. 1988;**332**(6162):323-327

Zenapax. Methods. 2005;**36**(1):69-83

It draws attention when analyzing the therapeutic mAbs in the market that the majority of them target cancer and autoimmune diseases, while some are directed to other conditions and very few are directed to infectious diseases treatment. It is also more astonishing since the first use of antibodies in immunotherapy fought against infectious diseases by the end of the nineteenth century. One obvious reason is that bacterial infections can be treated with antibiotics and many can be prevented by vaccination. Viral infections, on the other hand, are more complicated to treat by vaccination or treatment with antibodies as some viruses exhibit high mutation rates.

Broadly neutralizing mAbs to influenza viruses can be used to probe *in vitro* vaccine candidates and provide useful information for understanding data generated by preliminary *in vivo* studies, contributing to a universal influenza virus vaccine strategy [148, 149]. The identification of new conserved epitopes resulted from analysis with two broadly neutralizing mAbs, specific for the HA2 subunit of influenza virus belonging to different clades. Both mAbs were generated by phage display from B cells of an influenza vaccinated individual [150] and from a "nonimmune" human antibody library [151]. Contrary to the disadvantages listed for phage display libraries, these are high affinity mAbs, in the range of nanomolar and picomolar, respectively.

Generation of mAbs by phage display technology was a breakthrough since this technology opened possibilities to isolate human antibodies for any kind of epitope/antigen without immunization. The success of this technology can be observed by the approval of some drugs, mAbs and other kinds of proteins, and many more are under clinical studies at different stages. There are some candidates for Phase 3 clinical trial, bringing promises of new drugs in the near future [25, 134]. As a perspective for infectious diseases, this technology should be more widely applied for rapid screening of antibodies for diagnostic or therapeutic purposes based on immune or naïve human libraries when epidemic infectious disease breaks without an available drug for its treatment. Other perspective concerns the combinatorial library construction. Recently, the human antibody repertoire derived from blood of human naïve or immunized donors has been intensively analyzed by next-generation sequencing [152, 153]. Advances in the knowledge of the human antibody repertoire would help in the designing of antibody libraries and for antibody maturation of existing human libraries, making possible the selection of mAbs with higher affinity for clinical use.
