Fig. 1.

Backcross mapping of protection conferred by fp-IBD1 vaccination to bursal damage by IBDV strain F52/70 challenge in two families derived from line 6₁ (MHC haplotype B2), CB-12 (B12) and 15I (B15). The graphs represent bursal damages score, with 0 as no perceptible damage and 5 as extremely damaged (x-axis) against percentage birds with that score (y-axis). Upper two panels are birds from the parental lines 15I and 6₁, and birds from the backcross family 15I × F1(15I × 6₁) segregated into the homozygotes and heterozygotes. Lower two panels are birds from the parental lines 15I and C-B12, and birds from the backcross family 15I × F1(15I × C-B12) segregated into the homozygotes and heterozygotes