Individuals exposed to a foreign and clinically significant red blood cell (RBC) surface structure, known as a blood group antigen, can be alloimmunised and produce an antibody. During pregnancy, mothers who are exposed to a foreign, paternally-inherited, blood group antigen on foetal RBCs can also be alloimmunised. The maternal antibodies destroys foetal RBCs in subsequent pregnancies and, if left untreated, results in foetal death. This is called haemolytic disease of the foetus and newborn (HDFN).

HDFN occurs most frequently in pregnancies where the mother is exposed to the paternally-inherited RhD blood group antigen on foetal RBCs. In 1967, licensing and introduction of a prophylactic antibody product, RhD- immunoglobulin, for all RhD-negative women, was one of the major medical advances of the 20th century. These RhD-immunoglobulin injections prevented the mother from alloimmunisation when exposed to the foetal RhD-positive RBCs. However, there are ongoing problems and challenges associated with RhD- immunoglobulin as it is sourced from blood donors who are deliberately injected with RhD-positive RBCs to produce anti-D antibodies and then, repeatedly injected to maintain “high anti-D levels”. Developing an alternative recombinant antibody source for RhD-immunoglobulin has been difficult as the mechanism of action of RhD-immunoglobulin is unclear. The first component of this study aims to investigate a potentially new mechanism of action and use phage display to capture the complexity of RhD-immunoglobulin. The second component of this study aims to apply phage display for a blood group antigen, other than RhD. Maternal antibodies recognising rare blood group antigens on foetal RBCs are not detected during routine testing and can result in a severe case of HDFN, such as the ATML blood group antigen in the Augustine blood group system. The antisera for typing this antigen is currently sourced from one individual. A recombinant antibody alternative will improve the availability of typing reagents for the ATML blood group antigen to aid in future cases of HDFN.

High density cell culture systems offer the advantage of production of biopharmaceuticals in compact bioreactors with high volumetric production rates. However, Chinese hamster ovary (CHO) cells must be engineered to achieve maximum performance under the culture condition of choice. Cell line optimization requires a deep understanding of the cell metabolism as well as the development of bioprocess strategies to maximize cell performance. Here, our major interest is to investigate CHO cells during perfusion under different treatments to maximize its metabolic performance, stability and product yield.

Membrane-based systems have utility within a number of unit bioprocesses, and in purification offer some advantages over chromatography including overcoming solute diffusion limitations. Membrane chromatography can be used for purification of mAbs and other biomolecules. In membrane chromatography, the ligand, for example Protein A, is covalently attached to a membrane of regenerated cellulose. The pore size of the membranes is larger than those of chromatography beads enabling capture and polishing at much higher flow rates. This project will investigate integration of these technologies into biopharmaceutical manufacturing processes utilising model biopharmaceuticals.

The increasing demand for recombinant therapeutic proteins highlights the need to constantly improve the efficiency and yield of these biopharmaceutical products from mammalian cells, which is fully achievable only through proper understanding of cellular functioning. Towards this end, the current study exploited a combined metabolomics and in silico modelling approach to gain a deeper insight into the cellular mechanisms of Chinese hamster ovary (CHO) for high density cultures.

The Patheon process for high density cell culture (Patheon XD^® Upstream Processing (USP) technology) can result in up to a 25 fold increase in bioreactor output (cell density). The proprietary Patheon XD^® USP bioprocess may be further improved, if a systems biology driven understanding of the fermentation process is achieved. Understanding of the byproducts and metabolites produced, that favour high density will be used to generate an optimised bioprocesses.

This project will develop and evaluate a periodic counter current (PCC) chromatography and straight-through processing (STP) continuous three-step mAb purification process. Process intensification by implementing continuous or semi-continuous downstream processes in mAb production, for example, can contribute to significant cost-savings and improved throughput. Continuous processing also offers the possibility of increased automation of the process. The project will develop these bioprocesses using model proteins, thereby developing a new, innovative bioprocess platform for the large scale production of mAbs.

This project is focussed on upstream bioprocessing and investigates the similarity (identity) of recombinant protein biopharmaceuticals produced in batch culture compared to the same proteins produced in continuous culture. It will involve extensive physico-chemical characterisation using a variety of highly sophisticated analytical techniques. Of specific interest is the extent to which product characteristics can be manipulated using continuous process parameters (i.e. perfusion rate, bleed rate, temperature, pH, and critical media components for quality issues e.g. sugars).12, 13 The project could explore the design envelope for continuous bioprocesses and the potential for these to better meet biosimilar specifications. A successful outcome to this project will be knowledge into the effect of manufacturing process on the molecular identity of the therapeutic protein product, allowing the manufacturer to understand the potential impact of changes to the manufacturing process.

This project will investigate and compare the differential expression of different classes of proteins, namely antibodies and coagulation factors. Expression of antibodies is well characterised, with consistent yields of 3 g/L or better in optimised conditions. Commercial production of antibodies is therefore a fairly generic process. Conversely, coagulation factors are extremely difficult to express at high levels and each factor represents a unique manufacturing challenge. The project seeks to understand what cell machinery / processing mechanisms create the bottlenecks in production of recombinant coagulation factors. 9, 10 The project will involve metabolomic analysis, as well as protein and cell engineering. A successful outcome to this project will lead to yield improvements for the commercial production of recombinant coagulation factors (and potentially other therapeutic proteins), resulting in improved productivity and reduced manufacturing costs.

Typing reagents for hybrid glycophorin blood groups that are rare in Caucasians, but with prevalence of up to 8% in East Asian ethnic groups, are unavailable despite repeated attempts by various groups to use conventional approaches to produce useful mAbs. We will utilise naive human phage libraries to develop reagents that react with RBC with a phenotype defined by the most common hybrid glycophorin but not with pooled human RBC that do not display these antigens. The usefulness of the mAb produced as a typing reagent will be assessed by binding to the target hybrid glycophorin detected by flow cytometry. Subsequently reactivity using the standard immunohaematological agglutination based techniques will be assessed as well as characterising other features required for typing reagents, such as long term stability at room temperature.

Integral membrane proteins are attractive targets for research, diagnostic and therapeutic applications, as they act as biomarkers to define a particular cell type, developmental stage or disease type. As such, mAbs against cell-surface biomarkers are highly sought after as biological therapeutics, laboratory reagents or diagnostic reagents. Based on antibody phage display methodologies.6 AIBN has developed novel whole-cell biopanning techniques to improve the efficiency of screening antibody libraries on whole cells displaying biomarkers. The proposed collaborative project aims to pool the skills of AIBN and CSL researchers to further optimise the whole cell biopanning technique to isolate new mAbs against specific cell surface biomarkers that are of interest to CSL. The outcomes of this project would be further innovations in whole cell panning methodologies, as well as isolation of new antibodies of therapeutic significance.

Using N-ethyl-N-nitrosourea (ENU)-induced mutagenesis, ARCBS has identified a unique murine pedigree with a splice-site mutation in a functionally important domain of a gene encoding an acetyltransferase. Red Blood Cells (RBC) from homozygous mutants from this pedigree demonstrate significant modifications of carbohydrates and lack the erythroid lineage marker TER-119. We plan to investigate the extent to which these changes modify the susceptibility to infection for pathogens that target developing and mature cells of the erythroid lineage. We will compare RBC from homozygous and wild type (WT) mice to characterise the RBC surface and identify novel RBC targets to be used as a basis for the development of biopharmaceuticals for treatment of diseases where infectivity is mediated through RBC receptors (e.g. Malaria, Parvovirus (B19)).

The Patheon process for high density cell culture (Patheon XD® Upstream Processing (USP) technology) can result in up to a 25 fold increase in bioreactor output (cell density). CHO cell lines can be engineered to deliver maximal performance and productivity. The proprietary Patheon XD® USP bioprocess may be improved for suitability to high density culture, by engineering CHO cell lines with acquired properties that favour high density. In this project, development of a cell line(s) optimised for high density cell culture, utilising CRISPR and other cell line engineering techniques, will be investigated.

The majority of proteins generated by the Recombinant Protein Group within CSL to date for in vivo use are mAbs that are not dependent on post-translational modifications for activity. However, CSL now has several projects that are not antibody-focussed and require the generation of complex proteins, including FVII-HSA, FVIII, AAT and C1Inhibitor. The correct glycosylation and, in particular, sialylation of these recombinant therapeutic proteins are important for in vivo animal studies, as glycostructures can influence the pharmacokinetics and immunogenicity of the protein.11 The project aims to understand the effect of host cell line, manipulation of enzymes in the protein glycosylation pathway and culture conditions on glycostructures in recombinant therapeutic proteins. The project will also compare proteins expressed in the Wave Bioreactor to those in a stirred tank bioreactor, with respect to posttranslational modifications and quality.

Human neutrophil antigens (HNAs) are a group of 5 glycoproteins that are expressed on human neutrophils, and in some cases, also on other cells and tissues. Endogenous antibodies against HNAs have been implicated in cases of alloimmune neonatal neutropenias, autoimmune neutropenias, febrile transfusion reactions and transfusion-related acute lung injury (TRALI). The availability of mAbs to HNAs permits the use of solid phase assays to detect endogenous antibodies specific to these antigens. While mAb reagents against HNA-1, HNA-2, HNA-4 and HNA-5 antigens are available, there are not yet any mAbs available for HNA-3. This project aims to develop mAbs against the two alleles of HNA-3 that can then be used to develop cell-based assays to detect anti-HNA-3a and anti-HNA-3b antibodies in blood donors. Furthermore, this project aims to use the anti-HNA-3 mAbs in existing in vitro transfusion models to help understand the mechanisms by which TRALI develops.

Intracellular processes including protein transport, transcription and signalling present a range of new potential targets that could have application in the treatment of a variety of disease indications. The screening of chemical libraries for binders to intracellular targets has had limited success due to (i) the relative lack of binding clefts and hydrophobic pockets compared to those located on cell surface proteins and (ii) the small “footprint” to which a small molecule can bind on an extensive protein surface interface. As an alternative, antibody fragments are being explored as molecular entities that are capable of disrupting protein-protein interactions within the cell, traditionally thought to be undruggable.5 This project will investigate strategies for intracellular delivery of antibodies and antibody fragments, along with assessing the resulting impact on cellular processes. An antibody against the transcription factor SOX18 (created at AIBN and IMB) will be used as the initial model system for intracellular antibody delivery. A successful outcome of this project will be the establishment of platform technology for the delivery of antibody fragments to intracellular targets.

Project Team