No abstract

No abstract

No abstract

SUMMARYNewcastle disease virus (NDV) production by individual chick embryo cells was determined after infection of monolayer cultures, trypsinization and distribution of the ceils into a large number of test tubes so that each tube would contain an average of one cell (or in some experiments IO cells). The content of each tube was assayed for p.f.u. I8 h later. The statistical analysis of the results indicates the presence of at least three distinct populations of cells with regard to NDV production: one non-producing population (5o to 90 ~o of the cells); one low-producing population (80 ~o of the producing cells) and one high-producing (20 ~ of the producing cells).The relative proportions of these cell populations was the same whether primary, secondary or tertiary cultures were used, and also when the cell-cultures were obtained from different tissues of the chick embryo.