Fig. 1
Virus pathogenicity. Four-week old SPF chickens were inoculated with the three wild-type (wt) and mutant viruses. (a) Deaths were recorded daily, and a survival curve was established. *** P < 0.001, ** P < 0.01 in a Mantel-Cox log-rank test comparing the considered mutant with the wt-virus. (b-e) At the indicated times (D + 1 to D + 7 p.i.), M-segment viral RNA was quantified in the indicated tissues or swabs, and expressed as log10 of vRNA copies per mg of tissue or per swab. Wt, filled circles; 3841AA, open squares; A149V, black triangles. Null qRT-PCR values were arbitrarily assigned a + 1 value (100). ** P < 0.01, * P < 0.05 in pairwise Dunn’s post-tests comparing the considered mutant with the wt-virus in panels b, c and d. (f) Histological lesions of interstitial broncho-pneumonia in the lungs of the virus-infected birds were scored