Growth of rubella virus in primary rabbit kidney cell cultures maintained with and without calf serum

Rubella virus growth was tested in primary rabbit kidney cell cultures, maintained with or without calf serum. In fluid phase of the cultures maintained with 1.5% of heat-inactivated calf serum, the infectious virus titers were much higher than in the system without serum. The differences reached 1.5-2.0 log10 TCID50/ml. Virus multiplication curves also ran different courses. In serum-containing system virus titer increased up to the 9th day post infection, while without serum--only up to 4-5 days. The time of appearance and the type of cytopathic effect were not affected by the absence of serum or by its presence in a concentration of 1.5%.