Endogenous retroviruses transcriptomes in response to four avian pathogenic microorganisms infection in chicken

Abstract

Background Endogenous retroviruses (ERVs) are common in the genomes of vertebrates and have been implicated in a variety of host responses such as immunity, phenotypic character and disease occurrence. However, the impact of ERVs on chicken disease is not well understood. In particular, the expression profiles of chicken ERVs (ChERVs) in the infection of pathogenic microorganisms are not clear. Results In the present study, we systematically identified 436 full-length ChERVs from the chicken genome and analyzed their neighboring genes. Subsequently, ChERV transcriptomes were analyzed in chicken after subgroup J avian leukosis virus (ALV-J), avian influenza virus (AIV), Marek’s disease virus (MDV) and avian pathogenic escherichia coli (APEC) infection. We found that about 50%-68% of ChERVs were transcriptionally active in infected-samples and uninfected-samples, although the abundance of most ChERVs is relatively low. Moreover, compared to uninfected-samples, a few ChERVs were significantly differentially expressed in ALV-J (49 ChERVs), AIV (18 ChERVs), MDV (66 ChERVs) and APEC (17 ChERVs) infected-samples. Of these differentially expressed ChERVs, only ChERV-3 was simultaneously down-regulated in the four ERV transcriptomes analysis after ALV-J, AIV, MDV and APEC infection. Further verification experiments found that both the exogenous and endogenous expression of ChERV-3 env gene was inhibited after ALV-J infection in chicken fibroblasts. However, overexpression of ChERV-3 env could induce the expression of interferon-stimulated genes (ISGs), but did not affect the replication of ALV-J. Conclusions To our knowledge, this study systematically revealed the expression profile of ChERVS for the first time after the pathogenic microorganism infection in chicken. These findings may be of significance for understanding the role and function of ChERVs to response the pathogenic microorganism infection.