FIG 1.

Infectious titer, cell binding ability, and specific growth rate. Numbers of PFU/ml as infectious titer (a), host cell binding efficiency (b), specific growth rate estimated from a one-step growth curve (c), and values from a modified Gompertz model (d) were estimated to confirm whether the serial passages altered the RRV phenotypes. All experiments were conducted three times. The error bar indicates the standard deviations. While no significant differences in cell binding ability were observed, there were significant differences in infectious titer between the original population and the 0.1MOI-1_2, 0.1MOI-1_3, and 0.1MOI-1_5 populations. The specific growth rates of 0.001MOI-1_5 and 0.001MOI-2_5 populations, which were derived from both the one-step growth curve and the modified Gompertz model, were also significantly larger than those of the original population (**, P < 0.01; *, P < 0.05; Student's t test).