LARGE DELETIONS IN THE 5'-UNTRANSLATED REGION OF FOOT-AND-MOUTH-DISEASE VIRUS OF SEROTYPE-C

Nucleotide sequences of the 5'-untranslated region (5'-UTR), at the 3' -side of the poly C tract, have been compared for 21 isolates of foot- and-mouth disease virus (FMDV) of serotype C from Europe, South Americ a and The Philippines. A deletion of 43 nucleotides is present in the European isolates as compared with most American isolates. A larger de letion of 86 nucleotides is present in some viruses from South America and The Philippines. These deletions include the loss of one or two p seudoknot structures predicted in this region of the 5'-UTR. In additi on, multiple point mutations have allowed the derivation of a phylogen etic tree which defines a grouping of isolates very similar to that de rived from the capsid gene sequences of the same viruses. The study pr ovides evidence that deletion (or addition) events must be very freque nt during evolution of FMDV type C, since viruses which are phylogenet ically very closely related (they belong to the same tree branch) may differ in the presence or absence of these deletions. Implications for FMDV evolution are discussed.