Volume 16, Number 18,
Issue of September 15, 1996
pp. 5644-5653
Copyright ©1996 Society for Neuroscience
Selective Vulnerability of Mouse CNS Neurons to Latent Infection
with a Neuroattenuated Herpes Simplex Virus-1
Received June 7, 1996; revised June 28, 1996; accepted July 2, 1996.
Santosh Kesari1, 2,
Virginia M.-Y. Lee2,
S.
Moira Brown3,
John Q. Trojanowski2, and
Nigel W. Fraser1
1 The Wistar Institute and 2 Department of
Pathology and Laboratory Medicine, University of Pennsylvania School of
Medicine, Philadelphia, Pennsylvania 19104, and 3 Medical
Research Council Virology Institute, Glasgow, Scotland G115JR
Herpes simplex viruses that lack ICP34.5 are neuroattenuated and
are presently being considered for cancer and gene therapy in the
nervous system. Previously, we documented the focal presence of the
latency-associated transcripts (LATs) in the hippocampi of
immunocompromised mice after intracranial (IC) inoculation of an
ICP34.5-deficient virus called strain 1716. To characterize further the
biological properties of strain 1716 in the CNS of immunocompetent
mice, we determined the extent of viral gene expression in different
cell types and regions of the CNS after stereotactic IC inoculation of
this virus. At survival times of >30 d after inoculation, we found
that (1) infectious virus was not detectable by titration and
immunohistochemical studies; (2) neurons harbored virus as demonstrated
by the detection of the LATs by in situ hybridization
(ISH); (3) transcripts expressed during the lytic cycle of infection
were not detected by ISH; and (4) subsets of neurons were selectively
vulnerable to latent infection, depending on the site of inoculation.
These results suggest that the absence of ICP34.5 does not abrogate
latent infection of the CNS by strain 1716. Additional studies of
strain 1716 in the model system described here will facilitate the
elucidation of the mechanisms that regulate the selective vulnerability
of CNS cells to latent viral infection and lead to the development of
ICP34.5 mutant viruses as therapeutic vectors for CNS diseases.
Key words:
herpes simplex virus;
ICP34.5;
latency;
neuron-specific
gene expression;
gene transfer;
viral vectors