Purification of total IgG from sars-cov-2 convalescent serum
Abstract
Background: Convalescent plasma contains neutralizing antibodies against SARS-CoV-2 but also potentially harmful inflammatory cytokines. Purified immunoglobulin G fractions offer a safer therapeutic alternative by concentrating antibodies while removing inflammatory mediators.
Objective: To establish a systematic protocol for purifying total IgG from SARS-CoV-2 convalescent serum using sequential chromatographic techniques.
Methods: Serum from 90 recovered donors was pooled into three independent samples. Purification employed four sequential steps: ammonium sulfate precipitation (50% saturation), Sephadex G-100 size-exclusion chromatography, DEAE-Cellulose ion-exchange chromatography, and Protein A affinity chromatography. Purity was assessed by native polyacrylamide gel electrophoresis and radial immunodiffusion.
Results: Starting from serum with 19.68 ± 7.27 mg/mL IgG and 110.47 ± 11.99 mg/mL total protein, the four-step purification yielded final IgG concentration of 1.14 ± 0.70 mg/mL with 1.19 ± 0.16 mg/mL total protein. This achieved 6.3-fold purification with purity ratio of 1.01 ± 0.38 and 5.8% recovery. Native PAGE confirmed high purity with a single IgG band.
Conclusion: Sequential chromatography successfully purified total IgG from convalescent serum, providing a laboratory-scale method for preparing safer immunoglobulin therapeutics.
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