E.coli (Protein Expression strains) HCP ELISA Kit (One-step), BP-QP-E032-96

Escherichia coli (Protein Expression Strains) serves as the core prokaryotic expression host for biotherapeutic products including recombinant cytokines, enzymes and polypeptide drugs.

2–100 ng/mL

Assay range

< 2.5 h

One-step, time to result

~0.577 ng/mL

LOD, LOQ ~1.55 ng/mL

E.coli (Protein Expression strains) HCP ELISA Kit (One-step), BP-QP-E032-96 kit box

Product overview

Escherichia coli (Protein Expression Strains) serves as the core prokaryotic expression host for biotherapeutic products including recombinant cytokines, enzymes and polypeptide drugs. Host cell protein (HCP) residues generated during production and purification are critical process-related impurities. These trace contaminants may induce immunogenicity risks and compromise the purity and safety of finished products. HCP residual testing serves as a core assay item for process characterization, in-process control and product release. Critical raw materials including antigens and antibodies of this kit are independently manufactured by Zhuhai Biori Biotechnology Co., Ltd. Comprehensive method-performance validation of the kit has been conducted in accordance with the United States Pharmacopeia, Chinese Pharmacopoeia, European Pharmacopoeia and other regulations, satisfying the technical requirements for HCP testing stipulated by domestic and international biopharmaceutical regulatory authorities. The limit of detection (LOD) of the kit is approximately 0.577 ng/mL, and the limit of quantitation (LOQ) is approximately 1.55 ng/mL.

Features and applications

Features

Product type: One-step ELISA Kit
Target Expression System: E.coli (BL21&W3110)
Assay Range: 2-100 ng/mL
Time to result: <2.5h
LOD: ~0.577 ng/mL
LOQ: ~1.55 ng/mL
Specificity: No cross-reactivity with Pichia pastoris, Sf9, MDCK and CHO HCP.

Applications

The E.coli (Protein Expression Strains) HCP ELISA Kit (One-step) is intended for quantitative determination of host cell proteins (HCPs) in recombinant protein biopharmaceutical products, such as insulin, interferon, and human growth hormone.
The kit can quantify residual HCP in purified intermediates, drug substance, and drug product, and can be used for process optimization, process monitoring, and product release.
This is a generic kit and is not limited to a specific purification process. It broadly recognizes and detects HCPs originating from expression strains BL21 and W3110. For HCPs originating from other expression strains, sample suitability should be verified.
The kit is for research use only and not intended for clinical use.

Components

Component	Quantity	Product No.
E.coli-E HCP Calibration Standards	2 vials	BPA-001
Anti-E.coli-E HCP Microplate Strips	96 wells	BPB-001
Anti-E.coli-E HCP:HRP (100×)	120 μL × 1 tube	BPC-001
TMB Substrate	12 mL × 1 vial	BPD-001
Stop Solution	6 mL × 1 vial	BPE-001
Diluent	50 mL × 1 vial	BPF-001
Wash Concentrate (20×)	50 mL × 1 vial	BPG-001
Plate Sealing Film	2 pieces	BPI-001
Instruction Manual	1 copy	/

Performance data

Calibration Curve (Assay Range)

Description: The standards supplied with the kit and one blank sample were tested. Each concentration was tested in triplicate, and three independent runs were performed. The Calibration curve was fitted using a four-parameter logistic model.

BP-QP-E032-96 E.coli (Protein Expression strains) HCP ELISA Kit (One-step): Figure 1 Assay-Range Test Results — **Figure 1** Assay-Range Test Results

Conclusion: In three replicate experiments, the calibration curves fitted by the 4PL model showed R² ≥ 0.99, and both RE and CV were ≤ 15% at all concentration points (≤ 20% for the highest and lowest concentrations). The assay range of the kit is 2-100 ng/mL.

Accuracy

Description: A calibration curve was prepared over the validated range. Five quality control (QC) levels—ULOQ, high (H), medium (M), low (L), and LLOQ—were prepared, and each level was tested in triplicate.

Conclusion: The CV and RE of the measured concentrations were ≤20%.

Repeatability

Description: A calibration curve was prepared over the validated range. High, medium, and low QC samples were prepared and tested in eight parallel replicates.

Table 1 Repeatability Test Results

Theoretical Concentrate	HQC-75ng/mL	MQC-30ng/mL	LQC-5ng/mL
No. of Tests	8	8	8
Mean Measured Concentration(ng/mL)	73.454	30.184	5.069
Concentration CV(%)	4%	3%	5%

Conclusion: The CV of the measured concentrations were ≤20%.

Inter-Analyst, Inter-Day, Inter-Instrument Precision

Description: Prepare calibration curve together with HQC, MQC, LQC samples for testing of inter-analyst, inter-day and inter-instrument precision.

BP-QP-E032-96 E.coli (Protein Expression strains) HCP ELISA Kit (One-step): Figure 3 Precision Test Results — **Figure 3** Precision Test Results

Conclusion: The inter-analyst, inter-day and inter-instrument CV values were all below 20%, meeting the acceptance criteria.

Specificity

Description: A calibration curve was prepared over the validated range, and potential interferents were prepared in parallel. The low (L) QC level was selected as the final spike concentration.

Table 2 Specificity Test Results

Sample	Sample concentration	Measured concentration(ng/mL)	Spike recovery
Pichia pastoris HCP	1μg/mL	<LLOQ	96%
CHO HCP	1μg/mL	<LLOQ	98%
Sf9 HCP	1μg/mL	<LLOQ	88%
MDCK HCP	1μg/mL	<LLOQ	92%

Conclusion: The kit showed no cross-reactivity with Pichia pastoris, Sf9, MDCK, CHO host cell proteins at 1 µg/mL and the spike recoveries were within the acceptable range.