Herpes simplex virus-1 (HSV-1) is human alphaherpesvirus that establishes a lifelong latent infection in peripheral nerve ganglia following primary infection. HSV-1 infections are generally benign, although its capacity for neurovirulence and neuroinvasiveness are the primary mechanisms through which HSV-1 can cause harmful disease in humans, especially in neonates and immunocompromised hosts. Our overall objective is to develop a model for examining HSV-1 neuropathogenesis in human sensory ganglia in vivo. We will evaluate HSV-1 infection of human dorsal root ganglion (DRG) xenografts in mice with severe combined immunodeficiency (SCID), exploiting the system that we created to investigate varicella- zoster virus (VZV) neuropathogenesis. The biology of HSV-1 infection is similar to VZV in that both HSV-1 and VZV establish latency within sensory ganglia following primary infection. Studies of VZV in the SCIDhu DRG model have provided the first opportunity to examine replication of a human alphaherpesvirus within cells that comprise human DRG in vivo. The DRG xenograft model has the potential to reveal characteristics of HSV-1 neuropathogenesis in the natural human host tissue microenvironment in vivo in an experimental system that will add substantially to observations from rodent models. Experiments will address three specific aims: (1) we will define the course of events that follows HSV-1 inoculation of human DRG xenografts in SCID mice, identifying what cell types within DRG are permissive for HSV-1 gene expression, whether neurons and/or satellite cells become productively infected and whether HSV-1 undergoes the pattern of transition to persistence in human neurons that we have observed in VZV-infected DRG xenografts;(2) we will investigate HSV-1 gene functions through the evaluation of recombinant HSV-1 strains, in particular we will examine the requirement for HSV-1 thymidine kinase (TK) during initial infection and persistence in DRG, and gD mutants for their capacity for viral entry;(3) if HSV-1 is shown to establish persistence in DRG xenografts, we will assess whether this model can be used to study HSV-1 reactivation by explanting latently-infected DRG xenografts and treating with agents that trigger neural cell signaling pathways and increase HSV-1 reactivation in rodent models. This work is intended to demonstrate the feasibility of using DRG xenografts in SCID mice to explore the molecular mechanisms of HSV-1 neuropathogenesis in differentiated human sensory neurons and non-neuronal cells within their sensory ganglia tissue microenvironment in vivo. In addition to new insights about basic virus-host interactions, such a model has potential value for studying antiviral drugs and live attenuated HSV-1 vaccine candidates to treat or prevent human disease caused by this common virus.

Public Health Relevance

Herpes Simplex Virus 1 (HSV-1) causes oral and genital lesions and encephalitis. These infections remain an important public health problem in the United States. Serious complications from HSV-1 can occur in healthy people and in those who have diseases that impair their immune systems. Our goal is to develop a model to study how HSV-1 infects human nerve cells that will have potential value for developing new drugs and vaccines.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21AI081994-01
Application #
7638379
Study Section
Special Emphasis Panel (ZRG1-IDM-P (91))
Program Officer
Beisel, Christopher E
Project Start
2009-05-22
Project End
2011-04-30
Budget Start
2009-05-22
Budget End
2010-04-30
Support Year
1
Fiscal Year
2009
Total Cost
$201,893
Indirect Cost
Name
Stanford University
Department
Pediatrics
Type
Schools of Medicine
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305