Heritabilities for copy number variation of porcine endogenous retrovirus by a quantitative PCR

Pigs (Sus scrofa) have been expected to have organs transplanted to humans, but porcine endogenous retrovirus (PERV) is one of the risks because the PERV has the possibility to get infected with human cells. Therefore, the pigs are required to have as low a PERV copy number as possible. In this study, firstly, we investigated the estimates of heritabilities for the PERV copy numbers in the Vietnamese native breeds. Genomic heritabilities for four genes on PERV were estimated using the restricted maximum likelihood method with the genomic relationship matrix. The genomic heritability estimates of these genes ranged from 0.27 to 0.71, indicating that it would be possible for these genes not to follow the normal Mendelian inheritance. Secondly, we bred the pig population to reduce the pol gene number and estimated the heritability for the number. Despite the high heritability estimate for the pol gene (0.59), little improvement was progressed after selection for reducing the gene number in the three generations. In order to reduce the PERV copy numbers from the pig genome, it would be difficult to adapt only conventional breeding technology, and we need to consider using another technology like genome editing.