Accelerating the clinical development of protein-based vaccines for malaria by efficient purification using a four amino acid C-terminal ‘C-tag’

• Published in: International journal for parasitology Vol. 47; no. 7; pp. 435 - 446
• Main Authors: Jin, Jing, Hjerrild, Kathryn A., Silk, Sarah E., Brown, Rebecca E., Labbé, Geneviève M., Marshall, Jennifer M., Wright, Katherine E., Bezemer, Sandra, Clemmensen, Stine B., Biswas, Sumi, Li, Yuanyuan, El-Turabi, Aadil, Douglas, Alexander D., Hermans, Pim, Detmers, Frank J., de Jongh, Willem A., Higgins, Matthew K., Ashfield, Rebecca, Draper, Simon J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.06.2017; Elsevier Science
• Subjects: Animals; Biomanufacture; Blood-stage; Carrier Proteins - chemistry; Carrier Proteins - immunology; Carrier Proteins - metabolism; Cell Line; Cloning, Molecular; Malaria; Malaria Vaccines - immunology; Plasmodium falciparum; Plasmodium falciparum - metabolism; Protein purification; Rabbits; RH5; Vaccine; Plasmodium falciparum; Malaria; Protein purification; Vaccine; Biomanufacture; RH5; Blood-stage
• ISSN: 0020-7519; 1879-0135
• DOI: 10.1016/j.ijpara.2016.12.001

[Display omitted] •Fusion of a four amino acid ‘C-tag’ allows purification of a PfRH5 malaria vaccine.•Overall process yield of 40–45% and very high product purity (>99%) was achieved.•His6-tagged and C-tagged PfRH5 are conformational and bind to basigin.•C-tag will facilitate the clinical translation of difficult-to-produce antigens. Development of bespoke biomanufacturing processes remains a critical bottleneck for translational studies, in particular when modest quantities of a novel product are required for proof-of-concept Phase I/II clinical trials. In these instances the ability to develop a biomanufacturing process quickly and relatively cheaply, without risk to product quality or safety, provides a great advantage by allowing new antigens or concepts in immunogen design to more rapidly enter human testing. These challenges with production and purification are particularly apparent when developing recombinant protein-based vaccines for difficult parasitic diseases, with Plasmodium falciparum malaria being a prime example. To that end, we have previously reported the expression of a novel protein vaccine for malaria using the ExpreS2Drosophila melanogaster Schneider 2 stable cell line system, however, a very low overall process yield (typically <5% recovery of hexa-histidine-tagged protein) meant the initial purification strategy was not suitable for scale-up and clinical biomanufacture of such a vaccine. Here we describe a newly available affinity purification method that was ideally suited to purification of the same protein which encodes the P. falciparum reticulocyte-binding protein homolog 5 – currently the leading antigen for assessment in next generation vaccines aiming to prevent red blood cell invasion by the blood-stage parasite. This purification system makes use of a C-terminal tag known as ‘C-tag’, composed of the four amino acids, glutamic acid – proline – glutamic acid – alanine (E-P-E-A), which is selectively purified on a CaptureSelect™ affinity resin coupled to a camelid single chain antibody, called NbSyn2. The C-terminal fusion of this short C-tag to P. falciparum reticulocyte-binding protein homolog 5 achieved >85% recovery and >70% purity in a single step purification directly from clarified, concentrated Schneider 2 cell supernatant under mild conditions. Biochemical and immunological analysis showed that the C-tagged and hexa-histidine-tagged P. falciparum reticulocyte-binding protein homolog 5 proteins are comparable. The C-tag technology has the potential to form the basis of a current good manufacturing practice-compliant platform, which could greatly improve the speed and ease with which novel protein-based products progress to clinical testing.