Fig. 1.

In vitro and in vivo characteristics of the JS-2012 and its passaged strains. a One-step growth curves. PK-15 cells were infected at an MOI of 1 with each virus. Cell culture supernatants were harvested at 4, 8, 12, 18, 24, 36, and 48 h post infection. Virus titers at each time point were determined by the TCID₅₀ assay in Vero cells. The data represented means ± SD for 2 independent experiments per data point. b Plaques of JS-2012 and the serial passaged strains generated in infected PK-15 cells cultured at 37 °C for 4 days. c Relative plaque diameters of each virus were calculated and compared to those of PRV JS-2012. Meanwhile the average plaque diameter of PRV JS-2012 were set as 1. d Survival percentages of mice inoculated with 10⁴ TCID₅₀ of each virus per mouse. In JS-2012-infected group, a total of 2 mice were heavily infected and dead at 3 days post inoculation, and another 3 mice with severe neurological symptoms (self-mutilation) were euthanized respectively for animal welfare reasons; in F50-infected group, 2 of 10 mice exhibited severe pruritus and self-mutilation symptoms and were euthanized for animal welfare reasons at 5 days post inoculation; The remaining 43 mice in control group and JS-2012, F50, F91, F120-infected groups were survived and then euthanized till the end of the experiment