A study of the level of nucleotide sequence conservation between the RNAs of two types serotypes of foot-and-mouth disease virus.

The level of nucleotide sequence conservation between the RNAs of type A and type O foot-and-mouth disease virus (FMDV) has been compared by three methods. (I) RNA hybridization of fragments containing either the poly(C) tract at the 5' end of the RNA of the poly(A) tract at the 3' end of the RNA indicates that there is a similar level of sequence conservation (65% homology) across the genome. RNase T1 fingerprinting of these fragments did not show the presence of any long regions of completely conserved nucleotides apart from the poly(C) and the poly(A) tracts. (2) RNase T1 fingerprints of the RNA on the 5' side of the the poly(C) tract (the S fragment) show that there is more conservation in this region of the RNA than indicated by the hybridization results. (3) Direct nucleotide sequencing of the poly(C) tract and of the 54 nucleotides at the 5' end of the two genomes shows that there is considerable sequence conservation at the extreme 5' end of the RNA.