Conserved and distinct expression of circular RNAs in commercially used Marek’s disease vaccine viruses

ABSTRACT: Circular RNAs (circRNAs) are covalently closed RNA molecules, supporting a wide diversity of functions. While aberrant circRNA expression stands as a recognized hallmark of cancer development, our attention has turned to investigate their role in viral infections, specifically Mardivirus Gallidalpha 2 (GaHV-2, MDV) infection. In a previous study focused on the virulent GaHV-2, RB-1B strain, we extensively cataloged circRNAs produced from virulence genes, notably from the MEQ-vIL-8 locus and the Latency Associated Transcripts (LATs) gene. Building upon this groundwork, our current investigation uncovers novel loci expressing viral circRNAs in distinct stages of GaHV-2 infection. Furthermore, we extend our focus to viral circRNA signatures in three commonly used MDV vaccines, the avirulent GaHV-2 (CVI988- Rispens strain), non-oncogenic Mardivirus Gallidalpha 3 (GaHV-3), and non-oncogenic Mardivirus Meleagridalpha 1 (MeHV-1) commercially called Herpesvirus of Turkey (HVT). In these vaccine viruses, we identified viral circRNA expression from a locus antisense to the immediate early ICP4 gene a conserved feature across the three species. This region has been characterized herein for the first time in term of candidate LATs exons and introns for GaHV-3 and MeHV-1. Potential LATs circRNAs were then deeply analyzed and we observed both similarities and distinctions when compared to those of the virulent GaHV-2. Another conserved gene, encoding the DNA packaging protein, was identified as a source of circRNAs in all three species. Eventually, different levels of circRNAs expression were found from the meq locus between virulent and avirulent GaHV-2 strains. Our findings highlight a conserved pattern of viral derived circRNA expression in these related avian alphaherpesviruses. This conservation underscores the potential significance of these transcripts in completing the viral cycle and facilitating viral spread.

ORGANISM(S): Gallus gallus

PROVIDER: GSE293847 | GEO | 2025/08/22

REPOSITORIES: GEO