Evidence that Varicella Zoster Virus small non-coding RNAs can modulate viral replication.

Varicella-Zoster virus (VZV, HHV3) is a human alphaherpesvirus that causes varicella in primary infection and latently infects peripheral neurons. Its reactivation from latent latency results in painful Herpes Zoster. Small noncoding RNAs (sncRNAs), including microRNAs, are important actors in modulating gene expression in almost human herpesviruses. Potential VZV-encoded sncRNAs were predicted recently by bioinformatic analyses (Markus et.al, 2017). We initially showed that reducing levels of one of these 24 putative sncRNA (VZVsnc23) modulated viral spread. Here we present the results of testing an additional 12 inhibitors to putative VZVsncRNA to see if they affect growth of VZV.

ARPE19 cells infected at low MOI with VZV expressing mCherry were transfected either with a locked RNA antagonist to VZVsncRNAs or a scrambled RNA control. Spread of infection was determined by measuring the fluorescent area occupied by individual infected foci (FOI) in living cultures multiple days after infection. Measurement of viral yield was carried out using plaque assays.

Transfection of antagonists to VZVsncRNA9 or VZVsncRNA20 consistently and significantly increased, while antagonists to VZVsncRNA10/12/13/14 decreased, growth of VZV FOI. The effects of the antagonists were all confirmed by plaque assays. Antagonists to VZVsncRNA2/8/11/17/22 did not show consistent effects on viral spread in our assay system.

VZV replication therefore appears to be modulated by virally-encoded sncRNAs, similar to other herpesviruses, and regulation can be positive or negative. In addition to opening a new window into understanding regulation of VZV growth, these findings may support development of novel therapies for chickenpox and zoster targeting VZVsncRNA pathways.