Synthesis and assembly of a full‐length human monoclonal antibody in algal chloroplasts

Abstract

Monoclonal antibodies can be effective therapeutics against a variety of human diseases, but currently marketed antibody-based drugs are very expensive compared to other therapeutic options. Here, we show that the eukaryotic green algae Chlamydomonas reinhardtii is capable of synthesizing and assembling a full-length IgG1 human monoclonal antibody (mAb) in transgenic chloroplasts. This antibody, 83K7C, is derived from a human IgG1 directed against anthrax protective antigen 83 (PA83), and has been shown to block the effects of anthrax toxin in animal models. Here we show that 83K7C heavy and light chain proteins expressed in the chloroplast accumulate as soluble proteins that assemble into complexes containing two heavy and two light chain proteins. The algal-expressed 83K7C binds PA83 in vitro with similar affinity to the mammalian-expressed 83K7C antibody. In addition, a second human IgG1 and a mouse IgG1 were also expressed and shown to properly assemble in algal chloroplast. These results show that chloroplasts have the ability to fold and assemble full-length human mAbs, and suggest the potential of algae as a platform for the cost effective production of complex human therapeutic proteins.

Expression and membrane-targeting of an active plant cytochrome P450 in the chloroplast of the green alga Chlamydomonas reinhardtii

“…To date, chloroplast transformation of Chlamydomonas reinhardtii has been used to express soluble proteins such as antibodies or vaccine candidates (Demurtas et al, 2013;Tran et al, 2009), but to our knowledge no membrane-bound protein has been expressed in an active form. Moreover, there are reasons to consider that this may be intrinsically difficult to achieve; the thylakoid and envelope membranes differ radically in lipid composition when compared to other membranes (ca.…”

“…A fully functional human IgG1 monoclonal antibody against anthrax protective antigen 83 was expressed from two separate genes and assembled into a fully active antibody (Tran et al, 2009). In addition, immunotoxins for cancer therapeutics as well as vaccine candidates against malaria or foot-and-mouth-disease virus have been produced in the chloroplast Jones et al, 2013).…”

A Chlamydomonas zöldalga nemzetség algáinak szerepe a biotechnológiában és helyük a zöldalgák rendszerében

“…A rekombináns fehérjéket három csoportra oszthatjuk: monoklonális antitestek, vakcinákhoz használt antigének és terapeutikus fehérjék. A monoklonális antitesteknek a rákkutatás területén van jelentős szerepük (Tran et al 2009). Az antigéntartalmú vakcinák antitest termelésére serkentik a szervezetet, amely fokozza az immunrendszer működését.…”

Lepidopteran cells, an alternative for the production of recombinant antibodies?

“…For example, the unicellular alga Chlamydomonas reinhardtii is able to produce antibodies after complete transformation of the chloroplasts genome. 140 Chloroplast expression presents unique attributes over the transformation of the nuclear genome: the integration of the transgene by homologous recombination, high expression rates, the ability to process polycistronic transcripts and no gene silencing. Soluble recombinant proteins are accumulated in the chloroplast but are not secreted.…”