The Cellular and Viral circRNAs Induced by Fowl Adenovirus Serotype 4 Infection

Xiao-Na Liu; Xiao-Ran Guo; Ying Han; Tian Tian; Jian Sun; Bai-Shi Lei; Wu-Chao Zhang; Wan-Zhe Yuan; Kuan Zhao

doi:10.3389/fmicb.2022.925953

The Cellular and Viral circRNAs Induced by Fowl Adenovirus Serotype 4 Infection

Front Microbiol. 2022 Jun 2:13:925953. doi: 10.3389/fmicb.2022.925953. eCollection 2022.

Authors

Xiao-Na Liu¹, Xiao-Ran Guo¹, Ying Han¹, Tian Tian¹, Jian Sun¹, Bai-Shi Lei¹, Wu-Chao Zhang¹, Wan-Zhe Yuan^{1

2}, Kuan Zhao^{1

2}

Affiliations

¹ College of Veterinary Medicine, Hebei Agricultural University, Baoding, China.
² Hebei Veterinary Biotechnology Innovation Center, Hebei Agricultural University, Baoding, China.

Abstract

Circular RNAs (circRNAs) are a new class of noncoding RNAs that play vital roles in many biological processes. Virus infection induces modifications in cellular circRNA transcriptomes and expresses viral circRNAs. The outbreaks of Hydropericardium-hepatitis syndrome (HHS) caused by fowl adenovirus serotype 4 (FAdV-4) have resulted in huge economic losses to the poultry industry worldwide. To investigate the expression of circRNAs during FAdV-4 infection, we performed transcriptome analysis of FAdV-4-infected leghorn male hepatoma (LMH) cells. In total, 19,154 cellular circRNAs and 135 differentially expressed (DE) cellular circRNAs were identified. The characteristics of the DE cellular circRNAs were analyzed and most of them were related to multiple biological processes according to GO and KEGG enrichment analysis. The accuracy of 10 cellular circRNAs were verified by semiquantitative RT-PCR and sequencing. The change trend was consistent with the RNA sequencing results. Moreover, 2014 viral circRNAs were identified and 10 circRNAs were verified by the same methods. Our analysis showed that seven circRNAs with the same 3' terminal and variable 5' terminal regions were located at pTP protein and DNA pol protein of FAdV-4, which may be generated via alternative splicing events. Moreover, the expression level of viral circRNAs was closely related to the replication efficiency of the virus and partial of the viral circRNAs promoted the replication of FAdV-4. Competing endogenous RNA analysis further showed that the effects of cellular and viral circRNAs on host or viral genes may act via miRNAs. Collectively, our findings first indicate that FAdV-4 infection induced the differential expression of cellular circRNAs and FAdV-4 also expressed viral circRNAs, some of which affected FAdV-4 replication. These findings will provide new clues for further understanding FAdV-4 and provide a basis for investigating host-virus interactions.

Keywords: FAdV-4; cellular circRNAs; miRNA; viral circRNAs; virus replication.