DNA-SEQUENCE VARIATION AS A CLUE TO THE PHYLOGENESIS OF ORTHOPOXVIRUSES

We have sequenced DNA equivalent to the E5R ORF of Copenhagen vaccinia virus from an additional strain of vaccinia and from cowpox (three st rains), camelpox (two strains), taterapox and ectromelia viruses. None of these showed the disruptions previously reported in the equivalent region of monkeypox virus. We also constructed a viable recombinant o f vaccinia virus strain Dairen in which the E5R sequence was disrupted by a 436 bp deletion and substitution of the B. coli gpt gene. Quanti tative analysis of the sequences, including available sequences from m onkeypox, variola and vaccinia viruses revealed four main groupings, n amely cowpox, ectromelia, monkeypox and a cluster which includes vario la, camelpox, taterapox and vaccinia viruses. It was noted that, at ov er 75% of the positions which differentiated species, all species but one had a common nucleotide. Although the analysis covers one single g ene only, the results accord with what is known of the biology of the viruses.