A STUDY ON THE CHARACTERISTICS OF LA SOTA STRAIN OF NEWCASTLE-DISEASEVIRUS ADAPTED TO GROW IN A CELL-LINE FROM BOVINE EMBRYO KIDNEY (BS BEK)/

The lentogenic La Sota strain of Newcastle disease virus (NDV) was ada pted to grow in the BS/BEK cell line of bovine embryo kidney origin wi th a infectious titre similar to that in chicken embryos. No modificat ion in the biological properties was detected after serial passages in the cell line, as indicated by CPE and by size and shape of the plaqu es. By contrast, the intracerebral pathogenicity index test, determine d in 1-day-old chicks, was lower than for La Sota grown in chicken emb ryos. However, the immunogenicity of the cell culture adapted virus di d not show any variation as demonstrated by serological response and b y protection following challenge with virulent NDV. Accordingly, it ap pears that La Sota grown in cell cultures has retained its biological and immunological characteristics and if these results are confirmed b y field trials and long term protection tests, the use of the BS/BEK c ell line could be an alternative to chicken embryos for the cultivatio n of NDV.