Effect of lysosomotropic agents on the foot-and-mouth disease virus replication.

The effect of two lysosomotropic agents, NH4Cl and chloroquine, on the foot-and-mouth disease virus (FMDV) replicative cycle was studied. When the drugs were present throughout the viral replicative cycle, an important inhibition of viral RNA synthesis and virus production was detected. The inhibition of viral RNA synthesis was maximal when the drugs were present from 30 min before virus infection up to 30 min after that. Otherwise, if the agents were added once the viral synthesis has started (150 min p.i.) the effect was not evident. The agents neither exerted direct virucidal effects, nor did they affect viral adsorption. The results indicate that the lysosomotropic agents affect preferentially an early intracellular event during the viral infective cycle.