LATENT AND LYTIC INFECTION OF ISOLATED GUINEA PIG ENTERIC NEURONS BY VARICELLA ZOSTER VIRUS (VZV)

*J.J. Chen (1), A.A. Gershon (2), Z.-S. Li (1), J.-H. Zhang (2) &
M.D. Gershon (1)
Departments of (1) Anatomy & Cell Biology and (2) Pediatrics, Columbia University, College of P&S, New York, NY, USA

It is important to be able to study VZV in neurons that are like those in ganglia that the virus infects in situ. Intrinsic sensory neurons are present in the enteric nervous system as well as in dorsal root and cranial nerve ganglia. We tested the hypothesis that VZV infects and becomes latent in guinea pig enteric neurons, which are an easily accessible model system. Myenteric ganglia were isolated, individually or with non-neuronal cells, from the guinea pig's small intestine. The growth of non-neuronal cells was suppressed with mitotic inhibitors. Cultures of individually selected ganglia were infected with ~500 pfu, while the ganglia with non-neuronal cells were infected with ~2500 pfu of cell-free VZV and maintained for 1-10 weeks. No morphological effects of infection were seen in the cultures of individually isolated ganglia; however, the presence of mRNA encoding ORFs 4, 21, 29, 40, 62, 63 and the corresponding proteins, indicated that the ganglia were infected. DNA, but neither mRNA encoding gC, gE and gI, nor the respective proteins, were observed; ORFps 29, 62, and 63 were exclusively cytoplasmic. VZV infection was therefore latent. When ganglia were isolated with non-neuronal cells, neurons, which could survive for > 1 month harboring latent VZV, died soon after inoculation; most of the remaining cells, through which VZV spread slowly (forming syncytia), were non-neuronal. Infected ganglia now contained mRNA encoding gC and gE as well ORFs 4, 21, 29, 40, 62, 63. gE immunoreactivity was abundant in trans-Golgi networks, late endosomes, and plasma membranes.
ORFps 29, 62, and 63 were intranuclear. VZV infection of the mixed cultures was therefore lytic. We conclude that neurons in isolated guinea pig enteric ganglia can be infected by VZV. By varying the conditions and multiplicity of infection, VZV can be induced to give rise either to latent infection of neurons or lytic infection in both neurons and non-neuronal cells. With few non-neuronal cells and a low multiplicity of infection, the VZV proteins that are expressed by the latently infected guinea pig neurons are those that are also expressed during latency by neurons in infected human ganglia.

Corresponding Author: Anne A. Gershon, Professor of Pediatrics, Department of Pediatrics, Columbia University, College of P&S, 630 West 168th Street, New York, NY, 10032, USA