An ELISA for quantification of recombinant human EGF in production process samples, serum and urine.

A sandwich enzyme-linked immunosorbent assay for quantifying a recombinant human Epidermal Growth Factor (rhEGF) protein used in a vacunal preparation is described. The protein was detected with high specificity in a short incubation time at elevated temperature, the assay showing a linear range between 0.0625 and 1 ng/mL. According to the regression analysis for the dilutional linearity data, r2 = 0.9998, slope = 1.07 and intercept = 0.05 were obtained. The intra- and inter-assay coefficient of variation, ranged from 0.79 to 2.87% and 4.87-9.69% respectively demonstrating high reproducibility and precision. The ANOVA test used in the specificity/interference study revealed parallelism among curves (p > 0.1), which indicated lack of interference in the working range. Recovery obtained in accuracy test for three concentration levels varied between 89 and 111%; evidencing a reliable analytical assay to characterize the quality of the recombinant protein in the manufacturing process at large scale, and other biological matrixes as: urine and serum.

Novel and sensitive ELISA for the rapid quantification of recombinant p64K protein.

The antigenic P64k protein from the pathogenic bacterium Neisseria meningitidis has been used as an immunological carrier in several conjugated vaccines. The aim of this report was to develop and validate a sensitive sandwich enzyme-linked immunosorbent assay (ELISA) for the quantification of recombinant p64k protein, to perform both manufacturing process and identification in different vaccine preparations. Validation studies were performed according to the guidelines of the International Conference of Harmonization (ICH). The reference curve showed to be precise and accurate over the entire linear range of 1.25 and 20ng/mL with a limit of quantification validated to 1.25ng/mL. The intra- and inter-assay coefficient of variation ranged from 0.35 to 6.65% and 4.70 to 10.63%, respectively. The ANOVA test used in the specificity/interference study revealed parallelism among curves (p>0.1), which indicates the lack of interference in the working range. Recovery obtained from the accuracy test, using three concentration levels, varied between 94 and 111%, confirming the assay's reliability. The short-term study shown the P64k is stable to -20°C up to 1-week. This ELISA was fully used to assess its manufacturing process and molecular interaction issues in several vaccine preparations. Thus, this immunoassay could be an excellent analytical choice to characterize the quality of that recombinant protein in several contexts as manufacturing process and molecular conjugates.

A combinatorial strategy of a new monoclonal ELISA and immunoaffinity chromatography using sodium deoxycholate to increase the recovery of multimeric proteins like r-HBsAg.

In this work, a sandwich monoclonal-based ELISA for quantifying the HBsAg obtained from yeast cells was standardized and validated. The monoclonal antibody employed in this assay reacts uniformly with different molecular isoforms of r-HBsAg. Immunoassay allowed the r-HBsAg quantification in an analytical range 11.9-191.7 ng/mL. Inter- and intra-assay precision variation coefficients were between 0.77-3.43% and 1.95-8.89%, respectively, and the recovery ranged 98.2-100.8%; which confirms its reliability. r-HBsAg is a complex of carbohydrates, proteins and lipids assembled into spherical particles with an average diameter of 24 nm. Many host contaminants accompany this protein during purification process, which can interfere the antigen recognition by the immunoaffinity matrix. To solve this problem, the effect of several detergents in the quantification and purification of r-HBsAg were studied. The addition of the surfactant sodium deoxycholate (NaDoc) at 0.1% in this ELISA improved the recognition and quantification of r-HBsAg by 2.4-fold higher than untreated samples. Similar results were observed in the immunoaffinity chromatography where a 1.5-fold increasing recovery values was shown. The application of NaDoc allows to reduce the inhibitory effect upon the antigen-antibody recognition, increasing the quantification and immunoaffinity chromatography efficiency. This analytical combination could be applied to multimeric proteins like r-HBsAg of HB vaccine.