Determination of the number of proviral integrations in different chicken populations. A. Standard curve based on diluted plasmid with a PCR product. B. Relative copy numbers of env gene were examined by qPCR with primer d* and the numbers of integration per haploid genome were determined using the standard curve shown in A. Horizontal bars represent mean values of integration number for each population. One-way ANOVA together with Newman-Keuls test as a post-hoc analysis was utilized. Mean ± SEM: F9 = 15.42 ± 0.31, H41 = 11.01 ± 0.83, L41 = 14.34 ± 1.01, H45 = 8.87 ± 0.42, L45 = 13.73 ± 0.51, WL = 5.56 ± 0.46 and RJ = 3.59 ± 0.56. N = 82 in F9 birds and n = 10 in the other populations. F9, generation 9 of the advanced intercross line; H41 and L41, generation 41 of the HWS and LWS lines, respectively; H45 and L45, generation 45 of the parental lines; WL, White Leghorn and RJF, Red Jungle Fowl.