A point mutation in the putative ATP binding site of the pseudorabies virus US3 protein kinase prevents Bad phosphorylation and cell survival following apoptosis induction.

The multifunctional US3 protein kinase is conserved among alphaherpesviruses. Like the herpes simplex virus US3 protein kinase, the pseudorabies virus (PRV) US3 protein confers resistance against apoptosis. In the current report, we introduced a point mutation in the putative ATP binding site of the PRV US3 protein kinase.

Brn-3a suppresses pseudorabies virus-induced cell death in sensory neurons.

Sensory neurons of the trigeminal ganglion (TG) are of crucial importance in the pathogenesis of many alphaherpesviruses, constituting major target cells for latency and reactivation events. We showed earlier that a subpopulation of porcine TG neurons, in contrast to other porcine cell types, is highly resistant to cell death induced by infection with the porcine alphaherpesvirus pseudorabies virus (PRV). Here, we report that expression of Brn-3a, a neuron-specific transcription factor implicated in cell survival of sensory neurons, correlates with the increased resistance of TG neurons towards PRV-induced cell death.

Alpha-herpesvirus glycoprotein D interaction with sensory neurons triggers formation of varicosities that serve as virus exit sites.

Alpha-herpesviruses constitute closely related neurotropic viruses, including herpes simplex virus in man and pseudorabies virus (PRV) in pigs. Peripheral sensory neurons, such as trigeminal ganglion (TG) neurons, are predominant target cells for virus spread and lifelong latent infections. We report that in vitro infection of swine TG neurons with the homologous swine alpha-herpesvirus PRV results in the appearance of numerous synaptophysin-positive synaptic boutons (varicosities) along the axons.

Cell type-specific resistance of trigeminal ganglion neurons towards apoptotic stimuli.

Trigeminal ganglion (TG) neurons are important target cells for many alphaherpesviruses and constitute a major site of virus latency and reactivation. Earlier we showed that porcine TG neurons are remarkably more resistant towards (apoptotic) cell death resulting from infection by the swine alphaherpesvirus pseudorabies virus (PRV) compared to a broad range of other primary porcine cell types and that this resistance does not depend on the strongly anti-apoptotic US3 viral protein kinase (Geenen, K., Favoreel, H.

Higher resistance of porcine trigeminal ganglion neurons towards pseudorabies virus-induced cell death compared with other porcine cell types in vitro.

Trigeminal ganglion (TG) neurons are important target cells for many alphaherpesviruses, constituting major sites for latency/reactivation events. Here, the in vitro kinetics of productive infection of the swine alphaherpesvirus pseudorabies virus (PRV) and resulting cell death in primary porcine TG neurons were determined, and these were compared with similar kinetics in many other porcine cell types. Confocal microscopy showed that all TG neurons expressed late genes such as viral glycoproteins, and that these glycoproteins were processed through the Golgi and reached the cell surface as in other cell types, albeit with a delay of +/-2-6 h.

The pseudorabies virus US3 protein kinase possesses anti-apoptotic activity that protects cells from apoptosis during infection and after treatment with sorbitol or staurosporine.

Most large DNA viruses, like herpesviruses, encode anti-apoptotic proteins to interfere with the apoptotic cellular response to infection. Previous studies have shown that the US3 protein kinase of herpes simplex virus, in contrast to US3 of bovine herpes virus 1, is very potent in protecting cells from apoptosis induced by the virus itself or by a broad range of exogenous apoptotic stimuli. Here, we demonstrate that US3 of the swine alphaherpesvirus pseudorabies virus (PRV) suppresses PRV-induced apoptosis in swine-testicle (ST) cells at late stages in infection, and that it protects ST cells from apoptosis induced by either sorbitol or staurosporine.