The Distribution And Characteristics Of Endogenous Retroviroues In Major Agriculture Animals’ Genome

Endogenous retroviruses is a kind of reverse transcription factors. In the millions of years of evolution, ERVintegrated into the host genome by infecting germ stem cell. Then it becomed a part of the genome and inherited.In this paper, distribution and features of ERV on the main farm animals’(pigs, cattle, sheep and chickens) genomes were studied respectively. Then we searched the 20kb region near those ERV with full-length sequence for the exist of genes and analyze the fusion between ERV and immune-related genes. Finally, we discussed the potential impact of endogenous retroviruses on disease in PRRS case. The main results are as follows:1. ERV is widely distributed in the major agricultural animal genome, ERV-related sequences are accounted for bovine genome 10.41%, about 17.78% of sheep genome sequence, about 2.55% around 3.65% pig genome sequence and chicken genomes.2. ERV number on herbivores (cattle, sheep) genome far more than the number of non-herbivores (pigs, chickens) genome, wherein the bovine genome has had 827 full-length sequence ERV; sheep genome has had 689 full-length sequence ERV; pig genome has had 197 full-length sequence ERV; chicken genome has 191 full-length sequence ERV. And herbivores genome ERV classification complicated, there are many unknown class of ERV.3. In the non-herbivores (pigs, chickens) genome, ERV density on sex chromosome is greater than the density on the autosomes, while in herbivores (cattle, sheep) there is no significant differences between chromosomes.4. During both up and downstream of 10 kb region around the ERV with full-length sequence, we found 80 genes in pig genome,228 genes in bovine genome,349 genes in sheep genome and 103 genes in chicken genome.5. the case between ERV and host gene fusion is ubiquitous, including some important immune genes, such as IL17D gene (in pig); PIGR gene, IL1R1 gene, IFNAR2 genes and gene ILDR2 (in cattle); LY96 gene, LY6H gene and gene SEMA3D (in sheep).6. the number of PRRS candidate genes associated with PRRSV resistance is 670, of which GWAS screened two candidate genes (SLC4A 7 gene and gene PPT2); 660 (419 genes regulated,241 genes down-regulated) genes differentially expressed in 5-week-old Landrace pigs; 8 (7 genes were upregulated, a gene down-regulated) genes differentially expressed in 5-week-old Tongcheng pigs. Only the downstream of ENSSSCG00000012842 at 4985bp has a ERV with full-length sequence. The gene is in the histones path;its GC content is 60.98%.