The virtual sheep genome is essentially the human genome sequence reordered based on the coordinates of a set of 1172 sheep BAC-Comparative Genome Contigs (BAC-CGCs) built on the framework of the human genome.

The sheep BACs were positioned using BAC-end sequences determined at TIGR from the CH-243 sheep BAC library constructed at CHORI. The BAC-end sequences were mapped to the cow (bosTau2), dog (canFam2) and human (hg17) genome sequences to position the BACs and a complex integration process was used to combine all of the information together on the framework of the human genome.

The BAC-CGCs were built using only BACs that were tail-to-tail on the framework of the human genome. Other BACs mapped to the framework of the human genome in other conformations were used to link BAC-CGCs together. The sheep linkage map v4.6 was used to order and orient the segments.

In this process ~84k (48%) of the sheep BACs were mapped tail-to-tail and an additional -55k BACs were mapped with high confidence, with only one end mapping to the genome.

The UCSC liftover utility was used with an hg17 to virtual sheep genome chain file to liftover the features from the framework of the human genome

The advantage of the construction of the virtual sheep genome is that the high standard of assembly and annotation of the human genome, and other genomes, can be readily transferred to the virtual sheep genome using coordinate conversion.

The links below provide access to the mappings of the sheep BACs to the cow, dog and human genomes and to the annotated virtual sheep genome.