Margery L. Cook

Latent herpes simplex virus in spinal ganglia of mice.

Herpes simplex virus establishes a persistent, latent infection in spinal ganglia after mice have recovered from posterior paralysis. Infectious virus is replicated when these ganglia are explanted and maintained as organ cultures in vitro.

Latent herpetic infections following experimental viraemia.

The spectrum of tissues harbouring latent herpes simplex virus following intravenous inoculation of mice was defined by in vitro co-cultivation techniques. The virus could be detected in central and peripheral nervous systems (including adrenal medulla), but could not be found in any non-neural tissues. Spinal ganglia were the organs most commonly involved. The relationship of these findings to the natural history of herpetic infections is discussed.

Intraaxonal transport of Herpes simplex virus in the rat central nervous system

Light and electron microscopic observation 3--4 days after microinjection of Herpes simplex virus (HSV) into the left neostriatum of rat demonstrated the following results. (1) Virus labeled nerve cells were found in the ipsilateral substantia nigra; a large number of infected neurons were in the zona compacta and some were in the zona reticulata. No virus infection was evident in the contralateral side. (2) Virus labeled neurons were found in the cortex, a greater number ipsilaterally than contralaterally, and in the dorsal raphé nuclei. Cortical microinjection of HSV led to infection of some cortical cells but no neostriatal cells. We conclude, therefore, that spread of the virus to the cortex, the substantia nigra and the dorsal raphé following neostriatal injection was by retrograde axonal transport. (3) The left neostriatum, where HSV was injected, showed a surprisingly small number of virus infected neurons. The infected neurons were mostly the large neurons; the majority of medium sized neurons were well preserved. There was massive degeneration of nerve terminals throughout the neuropil. Most of these degenerating nerve terminals are considered to be afferent fibers.

Replication of varicella-zoster virus in cell culture: An ultrastructural study

In cultures of primary human amnion cells, varicella-zoster (V-Z) viruses first appear in nuclei as capsids which are freely dispersed, clustered, or in crystalline arrays. These capsids may be “empty” or contain several morphologically identifiable components including a dense core composed of deoxyribonucleic acid (DNA). Virions become morphologically mature when capsids containing DNA (nucleocapsids) acquire an envelope from the inner nuclear membrane during passage of the nucleocapsid to the cytoplasm. Once outside the nucleus, V-Z viruses appear pleomorphic, are often surrounded by a dense material, and exhibit a paucity of central dense cores. In thin sections, intact virions appear morphologically identical to other herpesviruses.

Latency Competence of Thirteen HSV-1 Temperature-sensitive Mutants

Thirteen temperature-sensitive (ts) mutants of HSV-1 were analysed for their capacity to establish latent infections in the brains of mice. Eleven of the mutants could be classified as latency-positive or -negative; two could not be assigned to either group. Leakiness of mutants in the brain and differences in particle/infectivity ratios were found not to play a role in the results. Ts+ revertants of selected latency-negative mutants regained the capacity to establish latent infections, indicating that it was the ts lesion in these agents which was involved in latency. Ultrastructural studies of neuroblastoma cells infected with various mutants and maintained at the restrictive temperature showed that no absolute correlations could be made between capacity to establish latent infection and synthesis of various morphologically identifiable virus products. Finally, from a comparison of latency characteristics with previously established polypeptide phenotypes of mutants it was concluded that one immediate early and one or more later virus functions are necessary for establishment and/or maintenance of the latent state.

Acute infection of differentiated neuroblastoma cells by latency-positive and latency-negative herpes simplex virus is mutants☆

Abstract Latent herpes simplex virus (HSV) appears to be selectively harbored in neurons. In initial attempts to understand this unique relationship, we have studied viral-neuronal interaction in vitro utilizing mouse C1300 neuroblastoma cells and selected latency-positive and latency-negative temperature-sensitive virus mutants. Comparative studies were made in baby hamster kidney (BHK) cells (where the mutants were first characterized) and, where possible, in mouse brain neurons in situ . Neurons in situ and neuroblastoma cells were productively infected by wild-type virus, the mutants were restricted at the non-permissive temperature, and DNA phenotypes in neuroblastoma cells were identical to those found in BHK cells. However, two mutants were found to have significantly different ultrastructural phenotypes at the restrictive temperature when neuronal infections were compared to BHK infections. In addition, the wild-type virus induced increased amounts of several polypeptides in neuroblastoma cells, and the processing of immediate-early polypeptides was impaired in infections with two mutants. These observations indicate that compared to BHK infections, neuronal infections do exhibit unique characteristics. Finally, the results are discussed with respect to both the general nature of latent herpetic infections and to the viral-specific information involved in establishment of these infections.

A herpes simplex virus mutant is temperature sensitive for reactivation from the latent state: Evidence for selective restriction in neuronal cells

When the replicative defect in the HSV-1 temperature sensitive mutant tsI was repaired, the agent derived (RI-1) was found to possess an additional temperature sensitive lesion limiting its reactivation from the latent state. Thus, when spinal ganglia from latently infected mice were scored for reactivation by cocultivating them with indicator cells in vitro, significantly more were found to be positive at 31 degrees than at 38.5 degrees. To assess a possible relationship between reactivation and replication in neurons, the replication of RI-1 in murine C1300 neuroblastoma cells was studied. In these cells, RI-1 was severely restricted, and viral replication was delayed at 38.5 degrees. Serial passage of RI-1 in neuroblastoma cells at the restrictive temperature resulted in selection of an agent which gained both the capacity to replicate efficiently in neuroblastoma cells and reactivate from the latent state at 38.5 degrees. However, the replication pattern of this neuron adapted virus in mouse embryo fibroblasts remained unchanged from the parental RI-1. Taken together, these results indicate that RI-1 possesses a neuron specific temperature sensitive replicative lesion which is also manifest during reactivation from the latent state.