BARNARD, B. J. H., 1984. Acid production by flavivirus-infected VERO and CER eel cultures. Onderstepoort Journal of Veterinary Research, 51, 8990 ( 1984). VERO and CER cell cultures infected with flaviviruses produce more acid than non-infected control cultures. Acid production is dependent on the presence of glucose. This phenomenon can be utilized for the titration of flaviviruses.