[Action of rifampicin on the reproduction of Aujeszky's disease virus].

The study on the effect of rifampicin on the reproduction of Aujeszky's disease virus (strains 2, 5, 7, 10, 12, and 17, which are virulent, and strain MK, which is an avirulent virus mutant) in cell cultures revealed that the formation of plaques is inhibited, though to a slighter extent, at a concentration of the inhibiting agent of 100 mug/ml, the value of their titer lowering by one logarithm. All virus strains have proved equally susceptible to the effect of rifampicin. During the virus multiplication in the presence of rifampicin the diameter of the plaques formed decreases from 2.8 to 0.5 mm, and with the avirulent strain MK it decreases up to 0.2 mm. They have rose tint in contrast to the plaques formed by strain 2, which are colourless. Rifampicin has no effect on virus reproduction when the cells are cultivated 24 hours prior to adding the antibiotic or when the virus adsorption on the cells takes place simultaneously with rifampicin. At lower rates the latter does not alter the reproduction process of the virus, however, at doses higher than 10 mug/ml it becomes toxic for the cells. Rifampicin inhibits the multiplication of the virus if it is added to the infected cell cultures up to the 12th hour following the adsorption of the virus. When 25-diacetyl-rifampicin is added to the nutrient medium the number of the plaques formed decreases but no change in their diameter occurs. However, with the avirulent MK strain both the number of plaques and their size decreases. Rifampicin B and rifampicin SV have no effect on the reproduction of Aujeszky's disease virus.