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Herpes simplex viruses 1 and 2 (HSV-1 and HSV-2) establish latency in sensory and autonomic neurons, from which they can reactivate to cause recurrent disease throughout the life of the host. Stress is strongly associated with HSV recurrences in humans and animal models. However, the mechanisms through which stress hormones act on the latent virus to cause reactivation are unknown. We show that the stress hormones epinephrine (EPI) and corticosterone (CORT) induce HSV-1 reactivation selectively in sympathetic neurons, but not sensory or parasympathetic neurons. Activation of multiple adrenergic receptors is necessary for EPI-induced HSV-1 reactivation, while CORT requires the glucocorticoid receptor. In contrast, CORT, but not EPI, induces HSV-2 reactivation in both sensory and sympathetic neurons through either glucocorticoid or mineralocorticoid receptors. Reactivation is dependent on different transcription factors for EPI and CORT, and coincides with rapid changes in viral gene expression, although genes differ for HSV-1 and HSV-2, and temporal kinetics differ for EPI and CORT. Thus, stress-induced reactivation mechanisms are neuron-specific, stimulus-specific and virus-specific. These findings have implications for differences in HSV-1 and HSV-2 recurrent disease patterns and frequencies, as well as development of targeted, more effective antivirals that may act on different responses in different types of neurons. Published version

Herpes simplex viruses (HSV1 and HSV2) establish latency in peripheral ganglia after ocular or genital infection, and can reactivate to produce different patterns and frequencies of recurrent disease. Previous studies showed that nerve growth factor (NGF) maintains HSV1 latency in embryonic sympathetic and sensory neurons. However, adult sensory neurons are no longer dependent on NGF for survival, some populations cease expression of NGF receptors postnatally, and the viruses preferentially establish latency in different populations of sensory neurons responsive to other neurotrophic factors (NTFs). Thus, NGF may not maintain latency in adult sensory neurons. To identify NTFs important for maintaining HSV1 and HSV2 latency in adult neurons, we investigated acute and latently-infected primary adult sensory trigeminal (TG) and sympathetic superior cervical ganglia (SCG) after NTF removal. NGF and glial cell line-derived neurotrophic factor (GDNF) deprivation induced HSV1 reactivation in adult sympathetic neurons. In adult sensory neurons, however, neurturin (NTN) and GDNF deprivation induced HSV1 and HSV2 reactivation, respectively, while NGF deprivation had no effects. Furthermore, HSV1 and HSV2 preferentially reactivated from neurons expressing GFRα2 and GFRα1, the high affinity receptors for NTN and GDNF, respectively. Thus, NTN and GDNF play a critical role in selective maintenance of HSV1 and HSV2 latency in primary adult sensory neurons. Published version

Herpes simplex viruses 1 and 2 (HSV-1 and HSV-2) infect and establish latency in peripheral neurons, from which they can reactivate to cause recurrent disease throughout the life of the host. Stress is associated with exacerbation of clinical symptoms and induction of recurrences in humans and animal models. The viruses preferentially replicate and establish latency in different subtypes of sensory neurons, as well as in neurons of the autonomic nervous system that are highly responsive to stress hormones. To determine if stress-related hormones modulate productive and latent HSV-1 and HSV-2 infection within sensory and autonomic neurons, we analyzed viral DNA after treatment of primary adult murine neuronal cultures with the stress hormones epinephrine and corticosterone. Both sensory trigeminal (TG) and sympathetic superior cervical ganglia (SCG) neurons expressed adrenergic receptors and glucocorticoid receptor. In productively infected neuronal cultures, epinephrine treatment significantly increased HSV-1 DNA replication and production of viral progeny in SCG neurons, but no significant differences were found in TG neurons. In contrast, corticosterone significantly decreased HSV-2 DNA replication and production of viral progeny in SCG neurons, but not in TG neurons. In quiescently infected neuronal cultures, epinephrine and corticosterone significantly increased HSV-1 reactivation from sympathetic SCG neurons, but not sensory TG neurons. In contrast, corticosterone increased HSV-2 reactivation from both SCG and TG neurons, but epinephrine had no effect. Adrenergic or epinephrine-induced reactivation of HSV-1 in SCG neurons involved activation of several adrenergic receptors, the cyclic AMP response element binding protein (CREB), the transcription factor β-catenin, and the c-Jun N-terminal kinase (JNK). Corticosterone-induced reactivation of HSV-1 in SCG neurons required activation of glucocorticoid receptor (GCR) and transcription factors CREB and JNK. In contrast, corticosterone-induced reactivation of HSV-2 in TG and SCG neurons could utilize either the GCR or mineralocorticoid receptor (MCR) and most likely involves the chromatin remodeling properties of those receptors. Thus, stress-related hormones, epinephrine and corticosterone, selectively modulate productive and quiescent HSV-1 and HSV-2 infections primarily in sympathetic, but not sensory, neurons through different mechanisms. These results have implications for describing a mechanism by which stress-induced reactivation may occur in humans. Ph. D. Herpes simplex virus type 1 and 2 (HSV-1 and HSV-2) are major human pathogens, which establish latency in neurons of the peripheral nervous system and reactivate to cause recurrent disease in humans. Physiological stress, which includes the secretion of the stress hormones epinephrine and cortisol, has been associated with increases in severity of clinical signs and increased recurrent disease in humans and animal models of herpetic disease. The mechanism by which physiological stress induces HSV reactivation has been assumed to be through suppression of the immune system. In addition, it has been assumed that sensory neurons harboring latent HSV are the primary source of reactivating virus for recurrent HSV disease. However, my dissertation provides evidence that the stress hormones epinephrine and corticosterone (the rodent equivalent of cortisol) can act on peripheral neurons in which the virus is latent, rather than through immune system suppression. In addition, my dissertation provides evidence that the autonomic nervous system, which modulates the physiological stress response, is an important source of reactivating virus to cause recurrent disease. The molecular pathway by which epinephrine and corticosterone induce HSV reactivation in primary adult murine neurons involves specific receptors, transcription factors, and protein kinases that could potentially be targeted in humans for inhibition of HSV reactivation and prevention of herpetic recurrent disease.