[Cloned variants of the L-IVP strain of the vaccinia virus].

Genomes of vaccinia strain L-IVP and its cloned variants were investigated by restriction and Southern blotting analysis. The strain L-IVP was shown to be heterogeneous and to consist of variants which differed in the genome structure and properties. Clone 1 derived from L-IVP was less reactogenic than the original strain for rabbits inoculated intradermally and had mutations in the right terminus of the genome. All the clones were stable in passages in the chorioallantoic membranes of developing chick embryos and roller BHK-21 cell cultures.