Suppression of Drug Resistance in Dengue Virus

Mateo, Roberto; Nagamine, Claude M.; Kirkegaard, Karla

To test whether a reduction in the accumulation of encapsidated RNA mimicked the reduction in infectivity, viral RNA was extracted from the virus preparations shown in Fig. 1D and quantified by quantitative reverse transcription-PCR (qRT-PCR) (Fig. 1E ). The cDNA of the wild-type virus had been engineered to contain a new restriction site so that the proportions of drugsusceptible and drug-resistant genomes could be determined molecularly ( Fig. 1F and G). AflII restriction digestion of amplified cDNA products resulted in no change in total or drug-resistant RNA in single infections versus coinfections (Fig. 1E) . Therefore, the dominant inhibition of the production of infectious virus was not caused by a failure to synthesize viral RNA or to package it into secreted particles. Instead, particles are generated that are noninfectious. This is consistent with the mechanism proposed for ST-148 inhibition, i.e., targeting core protein assembly and virion morphogenesis.