Study of genome homology of some orthopoxviruses

Homology between DNAs of some orthopoxviruses: vaccinia, neurovaccinia, cowpox, ectromelia, variola and white-pox was studied. By the method of molecular hybridization of labelled virion DNAs of the viruses studied with an excess of unlabelled vaccinia DNA and further treatment of the hybridized products by the single-stranded-specific nuclease S1, it was shown that the concentration of unlabelled vaccinia virus DNA, converting 50% of homologous labelled DNA into a hybrid, converted under similar experimental conditions into a hybrid 50% of labelled neurovaccinia virus DNA, 48% of white-pox virus DNA, 43% of variola virus DNA, about 30% of cowpox virus DNA and 27% of ectromelia virus DNA. Based on the quantitative data obtained the relationship between viruses of this subgroup and the possible origin of vaccinia virus is discussed.