The iridovirus (strain A3/12/98 PPD) was isolated originally from diseased brown-spotted
grouper, E. tauVina in Singapore and propagated on monolayers of GP cells, a permanent local
marine fish cell line derived from embryos of grouper, E. tauvina (Chew-Lim et al., 1994). GP cells were cultured in Eagles’ minimum essential medium (EMEM) containing 10% fetal bovine serum (FBS), 0.116 M sodium chloride, 100 IU ml−1 of penicillin and 100 _g ml−1 of streptomycin. The pH of the medium was adjusted to 7.2–7.4 with 7% sodium bicarbonate and buffered with 0.5% of 1 M N-[2-hydroxyethyl] piperazine-N_-[2-ehtanesulfonic acid] (HEPES). The cells were grown at 25 °C.