Fasting and overfeeding affect the expression of the immunity- or inflammation-related genes in the liver of poultry via endogenous retrovirus (ERV)

ABSTRACT It is known that nutrition and immunity are connected, but the mechanism is not very clear. Endogenous retroviruses (ERVs) account for 8-10% of the human and mouse genomes and play an important role in some biological processes of animals. Recent studies indicate that the activation of ERVs can affect the expression of the immunity- or inflammation-related genes, and the activities of ERVs are subjected to regulation of many factors including nutritional factors. Therefore, we hypothesize that nutritional status can affect the expression of the immunity- or inflammation-related genes via ERVs. To verify this hypothesis, the nutritional status of animals was altered by fasting or overfeeding, and the expression of intact ERV (ERVK18P, ERVK25P) and immunity or inflammation-related genes (DDX41, IFIH1, IFNG, IRF7, STAT3) in the liver was determined by quantitative PCR, followed by overexpressing ERVK25P in goose primary hepatocytes and determining the expression of the immunity or inflammation-related genes. The data showed that compared with the control group (no fasting), the expression of ERVs and the immunity- or inflammation-related genes was increased in the liver of the fasted chickens but decreased in the liver of the fasted geese. Moreover, compared with the control group (routinely fed), the expression of ERVs and the immunity- or inflammation-related genes was increased in the liver of the overfed geese. In addition, overexpression of ERVK25P in goose primary hepatocytes can induce the expression of the immunity or inflammation-related genes. In conclusion, these findings suggest that ERVs mediate the effects of fasting and overfeeding on the expression of the immunity- or inflammation-related genes, the mediation was varied with poultry species, and ERVs and the immunity- or inflammation-related genes may be involved in the development of goose fatty liver. This study provides a potential mechanism for the connection between nutrition and immunity.