Detection and control of host cell proteins

1. Detection and control of host cell proteins Introduction Firstly, Normally, the cell invaded by a virus called a host cell. Viruses are not shaped nucleus, whose genetic material inside generally is wrapped by the protein, after the virus invade the cell, using host proteins and other substances to make its own body. Similarly, host cell proteins (HPCs) is a type of protein mixture that is produced by genetic engineering strain or cell line with nothing to do with the purpose of genetic engineering, some of these proteins is necessary in the production process, engineering strains or cell lines survival, reproduction, and other normal physiological activities, with the objective product purification and cannot be removed, meanwhile, the composition and abundance of the HCP at all stages of production and the final product are quite different, it is up to many different factors. Genetic Engineering Development of host cell protein analysis As time goes by, scientists find amino acid sequence of the genetic engineering drugs itself, the molecular properties have a huge impact on the composition and abundance of the HCP, in addition, HCP’s composition is so complicated and affected by many elements that predicting risks of residues in HCP in the process of actual through non-specific clinical or experimental design in vitro is impossible. Therefore, it’s of the essence to do host cell protein HCP analysis, identification of host cell proteins and risk assessment. At present, the methods for HCP detection mainly include visual detection technology, quantification of host cell proteins and qualitative detection. However, the detection of HCP faces many challenges: 1) The content of HCP in gene engineering drug products is quite low, which is a huge gap with the concentration of product. 2) The subjects were a mixture of different proteins 3) The composition and concentration of HCP changed greatly at different stages of the production Thus, various detection methods need meet different requirements of production process design, verification and control. Let’s take some examples below.

2. ELISA An enzyme-linked-immunosorbent assay(ELISA) is the workhorse method for HCP testing due to its high throughput, sensitivity and selectivity, however dependence on the production of anti-Hcp antibodies, thus there are many limitations of the applications. Alternative approaches are also now emerging, such as 2D-DIGE and MS, which complement ELISA and allow the detection, identification and monitoring of specific HCPs. We anticipate that more fundamental understanding of impurities and the product itself would now be applied to upstream processing design(cell line selection and so on),and to downstream processing development. These will reduce or remove general and specific problematic HCPs before and during down stream processing. Summary In recent years, both production design and analysis of the genetic engineering drugs take HCP into consideration, while our understanding of genetic engineering drugs HCP is also deepening, from the choice of expression system, the nature of the genetic engineering drugs itself, and the interaction of HCP, culture week, culture conditions, state of cells, cell's response to the shear stress, the choice of purification methods such as multiple aspects of the composition of HCP, resolute, reason. there will be a new analytical techniques used for the detection and identification of HCP in the future, which is bound to further promote HCPs that are based on correct theoretical knowledge s to reduce or eliminate in genetic engineering drug, conducive to the design of the production process and control, to improve the production efficiency, removal of HCP, promote improving the quality of the genetic engineering drugs, and reduce the production cost.