XXXX A7(74) transduces hippocampal neurons and glial cells in a temperature-dependent dual manner.

@entity198 @entity3598 @entity281 @entity35 @entity3597
In central nervous system (CNS) tissue preparations, wild-type @entity3597 ( @entity3598 ) mainly infects neurons, and in vivo it causes lethal @entity198 in neonatal and adult rodents. The @entity3598 A7(74), by contrast, is avirulent in adult rodents, triggering only limited CNS @entity281 . To examine A7(74) @entity281 in hippocampal tissue, the authors constructed a replicon, termed @entity3598 (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 @entity281 was temperature-dependent. Indeed, at 31 degrees C both viral recombinants transduced significantly more baby hamster kidney cells than at 37 degrees C. When @entity35 hippocampal slices and dissociated cells were incubated at 37 degrees C, @entity3598 (A774nsP)-GFP transduced glial cells but virtually no neurons-the opposite of conventional @entity3598 . For VA7-EGFP at 37 degrees C, the preferred GFP-positive cells in hippocampal slices were also non-neuronal cells. At 31 degrees C, however, a more wild-type phenotype was found, with 33% and 94% of the GFP-positive cells being neurons for @entity3598 (A774nsP)-GFP in slices and dissociated cells, respectively, and 94% neurons for VA7-EGFP in slices. Immunochemical and electrophysiological analyses confirmed that at 37 degrees C virtually all cells transduced by @entity3598 (A774nsP)-GFP in slices were astrocytes, while at 31 degrees 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.
