Increased neurovirulence and reactivation of the herpes simplex virus type 1 latency-associated transcript (LAT)-negative mutant dLAT2903 with a disrupted LAT miR-H2

• Published in: Journal of neurovirology Vol. 22; no. 1; pp. 38 - 49
• Main Authors: Jiang, Xianzhi, Brown, Don, Osorio, Nelson, Hsiang, Chinhui, BenMohamed, Lbachir, Wechsler, Steven L.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.02.2016
• Subjects: Animals; Biomedical and Life Sciences; Biomedicine; Cell Line, Tumor; Disease Models, Animal; Female; Gene Expression Regulation, Viral; Herpes Simplex - pathology; Herpes Simplex - virology; Herpesviridae; Herpesvirus 1, Human - genetics; Herpesvirus 1, Human - metabolism; Herpesvirus 1, Human - pathogenicity; Humans; Immediate-Early Proteins - genetics; Immediate-Early Proteins - metabolism; Immunology; Infectious Diseases; Mice; MicroRNAs - genetics; MicroRNAs - metabolism; Neurology; Neurons - pathology; Neurons - virology; Neurosciences; Promoter Regions, Genetic; RNA, Viral - genetics; RNA, Viral - metabolism; Tissue Culture Techniques; Trigeminal Ganglion - pathology; Trigeminal Ganglion - virology; Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - metabolism; Virology; Virulence; Virus Activation - genetics; Virus Latency - genetics; HSV-1; Reactivation; miR-H2; LAT microRNA; Latency
• ISSN: 1355-0284; 1538-2443
• DOI: 10.1007/s13365-015-0362-y

At least six microRNAs (miRNAs) appear to be encoded by the latency-associated transcript (LAT) of herpes simplex virus type 1 (HSV-1). The gene for ICP0, an important immediate early (IE) viral protein, is anti-sense to, and overlaps with, the region of LAT from which miRNA H2 (miR-H2) is derived. We recently reported that a mutant (McK-ΔH2) disrupted for miR-H2 on the wild-type HSV-1 strain McKrae genomic background has increased ICP0 expression, increased neurovirulence, and slightly more rapid reactivation. We report here that HSV-1 mutants deleted for the LAT promoter nonetheless make significant amounts of miR-H2 during lytic tissue culture infection, presumably via readthrough transcription from an upstream promoter. To determine if miR-H2 might also play a role in the HSV-1 latency/reactivation cycle of a LAT-negative mutant, we constructed d LAT-ΔH2, in which miR-H2 is disrupted in d LAT2903 without altering the predicted amino acid sequence of the overlapping ICP0 open reading frame. Similar to McK-ΔH2, d LAT-ΔH2 expressed more ICP0, was more neurovirulent, and had increased reactivation in the mouse TG explant-induced reactivation model of HSV-1 compared with its parental virus. Interestingly, although the increased reactivation of McK-ΔH2 compared with its parental wild-type (wt) virus was subtle and only detected at very early times after explant TG induced reactivation, the increased reactivation of d LAT-ΔH2 compared with its d LAT2903 parental virus appeared more robust and was significantly increased even at late times after induction. These results confirm that miR-H2 plays a role in modulating the HSV-1 reactivation phenotype.