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The nucleotide sequences of the env genes of seven bovine leukemia viruses and the encoded peptide sequence were compared, with the objective of (i) determining the genetic distance separating bovine leukemia virus isolates from different geographical regions, (ii) identifying particular amino acids that contribute to the sequential and conformational epitopes, and (iii) relating such epitopes to their projected position in a three-dimensional model of the structure of the gp51 surface glycoprotein. Two bovine leukemia virus subgroups were clearly identified, a Japanese-American subgroup represented by strains lambda BLV-1, VdM, and FLK-BLV and a European subgroup by strains T15-2, LB285, and LB59. It was possible to identify amino acids that were important in determining three of the epitopes (F, G, and H) recognized by neutralizing monoclonal and polyclonal antibodies. On the model, these epitopes were adjacent and located on the exposed region of the molecule. Amino acid sequences contributing to a fourth cryptic epitope were identified; as predicted by the model, they lay on the opposite side to the neutralizable epitopes in a region involved in glycoprotein subunit association. The fact that this region is not normally exposed on the virion surface provides further evidence for the validity of the model.

Epigenetic phenomena, such as DNA methylation, which participate in the regulation of gene expression, can influence phenotypes. The influence of the embryonic environment on the adult phenotype, through epigenetic marks, has been observed in numerous cases. Recent studies show that epigenetic information may be transmitted across generations. Our aim was to observe if a modification of the quail embryonic environment would have transgenerational effects. We observed phenotypic differences in the third generation between 2 lines, obtained after treating (Epi+) or not treating (Epi-) eggs from a common set of founders G0, by injection of genistein. We used genistein as it is known to interfere with the epigenome, especially with DNA methylation. A “mirror” device was set, with parallel genealogies in each line, to minimize the putative influence of genetics on trait variability. After 3 generations without any further treatment, a significant difference in sexual maturity was observed between the lines, with the Epi+ G3 birds starting egg laying later. A significant interaction between line and sex was observed for 3-wk body weight and for eye temperature. Two behavioral traits in the G3 were also significantly affected by the initial treatment. Global methylation analyses are ongoing. These observations demonstrate the impact of a modification of the founders’ embryonic environment on the phenotype of quails, 3 generations later. While genetic variability cannot definitely be ruled out, the mirror animal device should have minimized its effects, and observed differences in the G3 may be attributed, at least partly, to transgenerational epigenetic phenomena.