Quality Evaluation and Application Observation of Recombinant Proteins in In Vitro Diagnostic Reagents

I. Application Positioning of Recombinant Proteins in In Vitro Diagnostic Reagents

Recombinant proteins are proteins expressed and purified through genetic engineering technology in specific host cells, and they constitute important upstream raw materials in the biological reagent and in vitro diagnostics industries. In common product lines such as immunoassays and molecular diagnostics, recombinant proteins can be used as coating antigens, labeled antibodies, standards, quality controls, or calibrators. Compared with human-derived or naturally extracted proteins, recombinant proteins have characteristics such as designable sequences, relatively stable supply batches, and more easily assessable safety risks, and therefore have attracted considerable attention in the research, development, and production of in vitro diagnostic reagents. In the industry, different expression systems and purification strategies are usually selected according to detection methodology, target analyte, and process requirements. The quality of recombinant proteins can directly affect the signal intensity, background level, and batch-to-batch consistency of diagnostic reagents; therefore, companies generally establish corresponding evaluation processes during the raw material screening stage.

II. Critical Quality Attributes and Batch-to-Batch Consistency Control

In industrial applications of recombinant proteins, common critical quality attributes include purity, biological activity, molecular weight distribution, endotoxin level, residual host cell proteins, and stability. Purity is generally characterized by methods such as electrophoresis and high-performance liquid chromatography; biological activity is evaluated by binding assays or enzymatic activity assays relevant to the intended use. Because batch-to-batch differences in raw materials may be carried over to the final product, companies usually impose relatively strict requirements on the batch-to-batch consistency of recombinant proteins. To control consistency, suppliers generally fix the expression vector, host cell, fermentation conditions, and purification process, and set acceptable ranges for critical process parameters. Before introducing a new batch, downstream users may also conduct small-sample verification or parallel comparison to observe its impact on the diagnostic reaction system. It should be noted that impurities such as endotoxins and residual nucleic acids may cause interference in specific detection scenarios even if they do not directly affect activity, so risk analysis should be conducted in combination with the intended use.

III. Supplier Screening and Documentation Management Recommendations

In the registration of in vitro diagnostic reagents and production quality management systems, raw material supplier management is an important link. When selecting recombinant protein suppliers, in addition to examining price and delivery cycle, greater attention should be paid to whether they have stable production processes, complete quality documentation, and necessary change management capabilities. Common industry practices include requesting certificates of analysis, safety data sheets, and proof of origin for critical raw materials, and conducting on-site audits when necessary. For diagnostic reagent manufacturers, it is also recommended to pay attention to whether suppliers provide advance notice before process changes and whether they provide sufficient stability data to support shelf-life setting. Some companies adopt dual-supplier or backup raw material strategies to reduce supply chain risk, but this brings additional verification workload. Overall, the supply quality and documentation completeness of recombinant proteins are often more practically significant than simply pursuing a single technical parameter.

IV. Industry Observations and Trends

As the in vitro diagnostics industry raises its requirements for precision and reproducibility, the quality control methods for recombinant proteins as core biological raw materials are also being continuously refined. In the future, the industry may place greater emphasis on structured data management, risk warning, and technical collaboration between suppliers and users. For R&D and production personnel, understanding the process origin and quality attributes of recombinant proteins helps to more rationally design diagnostic reagent formulations, optimize reaction systems, and form more complete raw material traceability evidence during registration and submission. It should be emphasized that the discussion in this article is limited to general industry technologies and quality management and does not involve efficacy or safety commitments for any specific product.