EN
Field strains of BHV1 isolated from bovine semen at different periods in Poland have been studied by the restriction enzyme analysis of DNA. It has been shown that the Aguille strain isolated in 1976 belongs to the subtype BHV 1.2 which comprises IPV strains. But strains III/2, III/3 and 6/42 isolated in 1981 belong to the subtype BHV 1.1 which comprises IBR strains.