Effect of serum on the production of foreign protein using vaccinia virus

Abstract

The effect of serum on recombinant protein production using vaccinia virus expression system was studied in both monolayer and suspension cultures of HeLa S3 cells. A model heterologous protein was $\beta$-galactosidase. Calf and horse sera were used, and their concentrations were 0.5-10\%(v/v). In monolayer culture, calf serum did not show any significant influence on $\beta$-galactosidase production. Horse serum, on the other hand, resulted in higher amount of product at 10\% concentration and its level increased continuously up to 96 hr p.i. Maximum total $\beta$-galactosidase values were $3.6 \pm 0.7 I.U./mL$ for calf serum and $2.8 \pm 0.7 I.U./mL$ for horse serum. In suspension culture, both serum showed similar pattern of their own as in monolayer culture. Maximum enzyme levels were 3.3 I.U./mL for calf serum and 3.6 I.U./mL for horse serum. Both sera showed lower maximum value, compared with monolayer culture. Cell numbers were also lower in suspension culture. However, enzyme activity per million cells were about 1.5-fold higher than that in the monolayer culture.