[Effect of 5-iodo-2-deoxyuridine (IDU) on Newcastle disease virus replication in cell cultures]

In chick embryo fibroblasts and in mouse fibroblasts of established L line, grown in the presence of IDU, the multiplication of Newcastle Disease virus was better and the CPE more distinct than in control cell cultures. In calf kidney cells only the CPE was enhanced. The most pronounced influence of IDU on virus multiplication was found after adding the analogue in maximum tolerated dose to the medium at the moment of cell culture preparation. The growth curve of virus in chick embryo fibroblasts grown in the presence of IDU shows the most distinct influence of this analogue with regard to LaSota strain. Already two days after inoculation with a smaller dose the titer was 2 log higher than in control cultures and the maximum difference of 3 log was found on the 5th day. In reference to Roakin strain the influence of IDU was weaker--maximum difference of 1,2 log on the fifth day after inoculation. Also the difference between the titers of virus in L cells grown in the presence of IDU and in the control ones, inoculated with LaSota strain was greater (about 1,5 lg during 2-8 days) than in the case of Roakin strain. In chick embryos treated with IDU intraallantoically at 24 and 48 hours before the inoculation with LaSota strain (only this was used) the enhancement of virus multiplication was much poorer than in chick embryo fibroblasts.