Influence of the chicken line on HVT load in feathers. Each HVT load corresponds to the log10 of HVT genomes number per million cells. Data are shown in Tukey boxes with the medians shown as thick horizontal bars. A HVT load per line regardless of the time. The medians (log) are indicated above each box. HVT loads were of moderate level in the four lines and not significantly different; B HVT load per line over time. He and Fa showed significant differences of HVT loads in feathers over time, whereas Nu and pH did not.