A comparative analysis of HSV-1 and PRV transcriptional activator VP16 in primary neurons

Abstract

The VP16 tegument protein of herpes simplex virus 1 (HSV-1) has been shown to have a role in reactivation of latent infection in the peripheral nervous system (PNS), but while it appears to activate viral gene transcription, it is unknown if this protein can also activate neuronal genes. Less research has been done on the VP16 homolog in the related pseudorabies virus (PRV) and any role it may play in activating neuronal genes. By using adeno-associated virus (AAV) vectors that encode either HSV VP16 or PRV VP16 (aka UL48), cultured superior cervical ganglia rat neurons (SCGs) can be transduced and made to express VP16 or UL48 independent of virus infection. Gene expression in SCGs transduced in this manner was compared using RNA-seq and RT-qPCR and it was found that the neuronal gene Jun was enriched in the presence of HSV VP16, Adcyap1 with PRV UL48, and Crem in the presence of both proteins. Subsequent analysis of subcellular localization in AAV vector-transduced and virus-infected SCGs showed that, while localization of Adcyap1 and Jun did not change with or without the presence of the VP16 proteins, Crem was nuclear only in the presence of PRV UL48. It appears that PRV UL48 may be increasing expression of Crem and Adcyap1 but only recruiting Crem to the nucleus for activation of viral gene expression. While the presence of HSV VP16 is connected to enrichment of Crem, that same nuclear localization is not observed, suggesting it may not play the same role in HSV-1 as in PRV.