Samatasvir achieved potent antiviral activity across genotypes : mean maximum reductions from baseline were 3.2-3 .6 ( genotype 1a ) , 3.0-4 .3 ( genotype 1b ) , 3.2-3 .4 ( genotype 3 ) , and 3.6-3 .9 ( genotype 4 ) log10/ml respectively ; no viral rebound was observed during the 3-day treatment period .