Application of a Serum/Protein-Free Medium for the Growth of Mammalian Cell Lines and High Level Production of Classical, Variant and Very Virulent Strain of Infectious Bursal Disease Virus (IBDV)

The aim of this study was to verify the capacity of IBDV strains, Lukert, F52/70 and very virulent Brazilian genotype (G11) to infect and replicate on cell culture maintained without serum or protein supplementation. BHK₂₁ and CER cells were directed adapted to growth under absence of protein and/or fetal bovine serum with addition of 5 µg mL^-1 of insulin-like growth factor I (IGF-I). The RPMI 1640 medium plus IGF-I was able to support both cell lines growth at a maximum of 3,3×10⁶ and 3,4×10⁶ cells mL^-1 for CER and BHK₂₁, respectively. The comparison between RPMI 1640 medium plus IGF-I and conventional MEM plus fetal bovine serum (FBS) growth curves demonstrated no significant difference, however the lowest surveillance of BHK₂₁ and CER cells under MEM plus BFS growth Both cells provided infectious virus titres of up to 10^5.5 50% tissue culture infective doses 100 µL^-1 (TCID₅₀ 100 µL^-1). Furthermore, they prove to be susceptible to infection with three different IBDV strains by culture both cells with RPMI 1640 medium plus IGF-I medium. It was concluded that both cells may be used for laboratory multiplication of IBDV strains without any serum and/or animal protein with a considerable ethical impact.