Stability of rubella complement-fixing antigens.

Various types of rubella complement-fixing (CF) antigen preparations derived from infected BHK-21 cell cultures were examined for stability to certain chemical and physical agents. Antigens studied included: infected culture fluids concentrated 100-fold, ether-treated fluid concentrates, alkaline buffer extracts of infected cells, and large- and small-particle CF antigens separated by Sephadex gel filtration. All preparations were stable at -20 C for months, and were unaffected by three cycles of freezing and thawing. Ether treatment rendered antigens highly susceptible to thermal inactivation at 56 C; untreated antigens were inactivated slowly and showed a persistent fraction of activity even after 2 hr. Large-particle antigen was found to be slightly more susceptible than small-particle antigen to thermal inactivation and ether treatment. CF activity in alkaline buffer extracts was more labile than that in untreated or ether-treated fluid concentrates upon dialysis, Sephadex gel filtration, and sucrose density gradient centrifugation.