Mutations in populations V19–4A and V19–4AB after 27 passages in BHK–21 cells a.

aThe consensus sequence of the entire viral genome was determined for FMDV populations V19–4A and V19–4B after 27 passages in cell culture.bFMDV genomic region analysed [15].cMutations and deduced amino acid substitutions are relative to the sequence of the parental clone FMDV WT (pMT28, described in Materials and Methods); residue numbering is according to [49]. Amino acid residues (single–letter code) are numbered individually for each protein from the N– to the C–terminus. Two residues separated by a bar indicate a mixture of two nucleotides in the population, according to the sequence chromatogram pattern. Procedures for nucleotide sequencing and identification of FMDV genomic regions are described in Materials and Methods.dPopulations in which the substitutions indicated in c were found.eMutation C4507U (that corresponds to amino acid substitution R55W in 2C) was dominant in V19–4B at passage 2 (Table 1) and had reverted by passage 27 (highlighted in italics).fSubstitution E8K (G5779A) was found repeated in population V19–4 at passage 27 in series A and B (underlined).