Journal Article

Semliki Forest Virus A7(74) Transduces Hippocampal Neurons and Glial Cells in a Temperature-Dependent Dual Manner

Raineteau, Olivier, Ehrengruber, Markus U, Hinkkanen, Ari E, Vähä-Koskela, Markus JV, Renggli, Martin, Lundstrom, Kenneth, Hennou, Sonia

2003

Overview

In central nervous system (CNS) tissue preparations, wild-type Semliki Forest virus (SFV) mainly infects neurons, and in vivo it causes lethal encephalitis in neonatal and adult rodents. The SFV strain A7(74), by contrast, is avirulent in adult rodents, triggering only limited CNS infection. To examine A7(74) infection in hippocampal tissue, the authors constructed a replicon, termed SFV(A774nsP)-GFP, expressing green fluorescent protein. The results were compared to replication-proficient recombinant A7(74) encoding GFP, named VA7-EGFP. As nonstructural gene mutations can confer temperature sensitivity, the authors also tested whether infection was temperature-dependent. Indeed, at 31°C both viral recombinants transduced significantly more baby hamster kidney cells than at 37°C. When rat hippocampal slices and dissociated cells were incubated at 37°C, SFV(A774nsP)-GFP transduced glial cells but virtually no neurons--the opposite of conventional SFV. For VA7-EGFP at 37°C, the preferred GFP-positive cells in hippocampal slices were also non-neuronal cells. At 31°C, however, a more wild-type phenotype was found, with 33% and 94% of the GFP-positive cells being neurons for SFV(A774nsP)-GFP in slices and dissociated cells, respectively, and 94% neurons for VA7-EGFP in slices. Immunochemical and electrophysiological analyses confirmed that at 37°C virtually all cells transduced by SFV(A774nsP)-GFP in slices were astrocytes, while at 31°C they also contained neurons. These results show that in addition to the developmental age, the temperature determines which cell type becomes infected by A7(74). Our data suggest that A7(74) is avirulent in adult animals because it does not readily replicate in mature neurons at body temperature, whereas it still does so at lower temperatures.

• Publisher: Informa UK Ltd,Taylor & Francis,Nature Publishing Group
• Subject: Animals / Arboviroses / Astrocytes / Astrocytes - cytology / Astrocytes - virology / Biological and medical sciences / Body temperature / Cells, Cultured / Central nervous system / Cricetinae / Encephalitis / Genetic Vectors / Genome, Viral / Glial cells / Green fluorescent protein / Green Fluorescent Proteins / Hippocampus / Hippocampus - cytology / Hippocampus - virology / Human viral diseases / Indicators and Reagents - metabolism / Infections / Infectious diseases / Interneurons - cytology / Interneurons - virology / Kidney - cytology / Luminescent Proteins - genetics / Medical sciences / Membrane Potentials / Miscellaneous / Neonates / Neuronal-glial interactions / Neurons / Organ Culture Techniques / Patch-Clamp Techniques / Phenotype / Phenotypes / Point mutation / Pyramidal Cells - cytology / Pyramidal Cells - physiology / Pyramidal Cells - virology / Recombinants / Semliki forest virus - genetics / Semliki forest virus - growth & development / Semliki forest virus - pathogenicity / Temperature / Transduction, Genetic / Tropical viral diseases / Viral diseases / Virulence / Virus Replication