Varicella-Zoster Virus and the Enteric Nervous System

Abstract

Varicella zoster virus (VZV) infects and becomes latent in sensory, enteric, and other autonomic neurons during the viremia of varicella. Reactivation of VZV in neurons that project to the skin causes the rash of zoster; however, reactivation of VZV in enteric neurons can cause a painful gastrointestinal disorder ("enteric zoster") without cutaneous manifestations. Detection of VZV DNA in saliva of patients with gastrointestinal symptoms may suggest enteric zoster. This diagnosis is reinforced by observing a response to antiviral therapy and can be confirmed by detecting VZV gene products in intestinal mucosal biopsies. We developed an in vivo guinea pig model that may be useful in studies of VZV latency and reactivation. VZV-infected lymphocytes are used to induce latent infection in sensory and enteric neurons; evidence suggests that exosomes and stimulator of interferon genes (STING) may, by preventing proliferation play roles in the establishment of neuronal latency.

Figure 1.

VZV^ORF66.GFP infection of isolated enteric neurons. The longitudinal muscle and adherent myenteric plexus were dissected from the guinea pig small intestine and dissociated with collagenase. The ganglia were manually selected under microscopic control, isolated, and grown in culture. Peripheral blood mononuclear cells (PBMCs) were obtained from a donor guinea pig and cocultured with VZV^ORF66.GFP to infect T cells in the population. The VZV^ORF66.GFP-infected PBMCs were then cocultured with the infected neurons. After 1 week in culture, the cells were fixed and immunocytochemically examined as whole mounts. The immunoreactivities of varicella-zoster virus (VZV) glycoprotein E ([gE] blue), a neuronal marker, PGP9.5 (red), and green fluorescent protein (GFP) were visualized. Coincident immunostaining of PGP9.5 and GFP is found in neurons, which do not contain gE immunoreactivity. Many gE-immunoreactive nonneuronal cells are seen, many of which cluster around the neurons. The bar = 100 µm.

Figure 2.

Intravenous injection of varicella-zoster virus (VZV)-infected peripheral blood mononuclear cells (PBMCs) leads to latent infection of the guinea pig enteric nervous system (ENS). Four weeks after injection of VZV-infected PBMCs, the gut was removed and the longitudinal muscle and adherent myenteric plexus were dissected from the guinea pig small intestine, fixed, and prepared as whole mounts for immunocytochemistry. The immunoreactivity of VZV ORF63 (red) was detected in the cytoplasm of myenteric neurons identified with antibodies to the neuronal marker HuC/D. The bar = 36 µm.