A microRNA of infectious laryngotracheitis virus can downregulate and direct cleavage of ICP4 mRNA

• Published in: Virology (New York, N.Y.) Vol. 411; no. 1; pp. 25 - 31
• Main Authors: Waidner, Lisa A, Burnside, Joan, Anderson, Amy S, Bernberg, Erin L, German, Marcelo A, Meyers, Blake C, Green, Pamela J, Morgan, Robin W
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-03-2011
• Subjects: Animals; Artificial Gene Fusion; Cercopithecus aethiops; COS Cells; Down-Regulation; Gene Expression Regulation, Viral; Genes, Reporter; Herpesvirus; ICP4; Iltovirus - physiology; Infectious Disease; Infectious laryngotracheitis virus; Luciferases - biosynthesis; Luciferases - genetics; microRNA; MicroRNAs - metabolism; RNA Stability; RNA, Messenger - biosynthesis; RNA, Messenger - genetics; RNA, Viral - metabolism; siRNA; Transcription factor; Viral Proteins - biosynthesis; Virus Replication; microRNA; siRNA; Infectious laryngotracheitis virus; Transcription factor; ICP4; Herpesvirus
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1016/j.virol.2010.12.023

Abstract Viral microRNAs regulate gene expression using either translational repression or mRNA cleavage and decay. Two microRNAs from infectious laryngotracheitis virus (ILTV), iltv-miR-I5 and iltv-miR-I6, map antisense to the ICP4 gene. Post-transcriptional repression by these microRNAs was tested against a portion of the ICP4 coding sequence cloned downstream of firefly luciferase. Luciferase activity was downregulated by approximately 60% with the iltv-miR-I5 mimic. Addition of an iltv-miR-I5 antagomiR or mutagenesis of the target seed sequence alleviated this effect. The iltv-miR-I5 mimic, when co-transfected with a plasmid expressing ICP4, reduced ICP4 transcript levels by approximately 50%, and inhibition was relieved by an iltv-miR-I5 antagomiR. In infected cells, iltv-miR-I5 mediated cleavage at the canonical site, as indicated by modified RACE analysis. Thus, in this system, iltv-miR-I5 decreased ILTV ICP4 mRNA levels via transcript cleavage and degradation. Downregulation of ICP4 could impact the balance between the lytic and latent states of the virus in vivo.