[Swine cell sublines with different ploidies. III. Susceptibility to foot-and-mouth disease virus].

IB-RS-10-II subline with tetraploid level cells was more susceptible to the infection by the foot-and-mouth disease virus (FMDV) ASQ-PG strain than IB-RS-10-I subline with diploid level cells, when number and size of plaques and cytopathogenic effect of the virus were used as criteria. Besides, the virus yield in one-cycle of infection was almost the double in IB-RS-10-II than IB-RS-10-I cell subline and the near-tetraploid cells were more susceptible to be infected by the virus than the near-diploid cells. However, in relation to FMDV ASQ-Pp strain the cell subline with a diploid level was more susceptible than that with a tetraploid level. The effects of polyionic compounds under specific experimental conditions were peculiar to each cell subline. 1. Pretreatment of cell monolayers with DEAE-dextran increased the diploid level cells receptivity to the virus, whereas that of the tetraploid level cells was affected only slightly; pretreatment with dextran sulphate did not affect the receptivity of both cell sublines. 2. Pretreatment of the virus with the polycationic compound increased significantly its infectivity to the cells of both sublines; pretreatment of the virus with polyanionic compound decreased significantly its infectivity to the diploid level cells but did not affect that for the tetraploid level cells. 3. Treatment of the agar overlay with the polycationic compound induced increase on the plaque size formed in both cell sublines and treatment with the polyanionic compound inhibited plaque sizes in both cell sublines. A correlation was not found between the susceptibility of both cell sublines to the infection and the chromosomic alterations.