Purification, potency and immunogenicity analysis of Vero cell culture-derived rabies vaccine: a comparative study of single-step column chromatography and zonal centrifuge purification

Continuous Vero cell lines are more suitable for large-scale production of rabies vaccine. The purification of Vero cell-derived rabies vaccine is critical because of the residual cellular DNA and serum proteins. The perfection of techniques using column chromatography with different matrix material, gel filtration and zonal centrifugation is of paramount importance for the optimal purification of rabies vaccine, leaving minimal residual cellular DNA, below the permissible level of 100 pg per dose and serum protein content of 1 ppm. In this study the potency, immunogenicity and safety of Vero cell-derived rabies vaccines were compared following purification by densely or loosely packed DEAE-sepharose CL-6B columns with different bed heights or by zonal centrifugation. The optimal virus recovery and maximum removal of substrate DNA and serum proteins were achieved only when the sepharose CL-6B column bed height was maintained at a thickness of 2-2.5 cm. The rabies virus material was purified by layering over the matrix without applying pressure. DEAE-sepharose CL-6B column purification using a simplified, cost effective technique as described in this study enhances the antigen yield by 50% in comparison with zonal purification.

Tangential flow filtration technology applicable to large scale recovery of diphtheria toxin

The commercial preparation of purified diphtheria toxoid primarily depends on the effective separation of the toxin from a large culture volume of Corynebacterium diphtheriae vaccine strain. Tangential flow or cross-flow filtration is gaining momentum in the processing of biologicals. This study deals with the separation of toxins using a microporous membrane (0.45-microm pore size) with operational variables like transmembrane pressure (TMP), cross flow rate and flux. Under the best conditions, 98% recovery was achieved. The data and conclusions presented here have been drawn from process development work employing available equipment.