The Vaccinia virus (vSC 8) expression system was employed for the synthesis of $\beta$-galactosidase, a model heterologous proteins. Six cell lines derived from Human cervical carcinoma, African green monkey kidney, Human hepatocellular carcinoma, Mouse brain were evaluated for comparing the amount of recombinant $\beta$-galactosidase. The HeLa HH cells had the highest yield among these cell lines and the Vero cells generally used in plaque assay had 4 fold lower than HeLa HH cells. Different pH, temperature, oxygen partial tension, osmolarity, serum concentrations were tested for the investigation the effects on production of a recombinant $\beta$-galactosidase. The optimal pH range of the $\beta$-galactosidase production and cell growth were between pH 7.0 and pH 8.0. Oxygen partial pressure ranged from 10% to 21% could not show any significant difference in $\beta$-galactosidase production but the production of $\beta$-galactosidase was abruptly decreased when oxygen partial pressure was lower than 1%. The increasing of osmolarity had worse effect on $\beta$-galactosidase production and cell growth. The $\beta$-galactosidase production at $32\,^\circ\!C$ was 3 times higher than at $37\,^\circ\!C$, but cell grew better at $37\,^\circ\!C$ than at $32\,^\circ\!C$. A increase in protein synthesis was also observed when serum concentrations were reduced but cell growth was reduced at lower serum concentration. The conditions that favor maximal cell growth could not lead to maximize the production of virus proteins. To determine $\beta$-galactosidase in animal cells, the cells have to been disrupted. In this study, four different cell disruption methods (freezing and thawing, sonication, homogenization and lysis buffer) were compared with regard to their efficiency in the determination of $\beta$-galactosidase activity. Further, the cell lines' susceptibility to cell disruption methods was investigated by employing three different animal cell lines(HeLa HH, Vero, and HeLa S3 cells) infected by recombinant Vaccinia virus(vSC 8) expression $\beta$-galactosidase gene. Regardless of cell lines used, three different cell disruption methods except homogenization did not show any significant difference in the final $\beta$-galactosidase activity recovered from the cells. Homogenization was quite inefficient. The use of lysis buffer was recommendable because of its convenient to keep cell samples collected during the culture frozen at $-20\,^\circ\!C$ until assay. Since thawing of the cells was enough to recover the $\beta$-galactosidase, further treatment on the frozen cells except thawing was unnecessary.
