Persistence of visna virus in cultured ferret brain cortex and fibroblasts.

Cerebral cortex tissue fragments from newborn ferrets have been cultured in vitro and, when exposed to visna virus, failed to exhibit a cytopathic effect but retained the genome of the virus in a quiescent state for 46 d before synthesizing plaque-forming virus for the subsequent 26 d. In contrast, infection of an established line of cells derived from a ferret's brain with visna virus resulted in the formation of the polykaryocytes typically produced by this virus and a limited synthesis of plaque-forming virus. Ferret cerebral cortex cultures may be suitable in vitro hosts for studies to define the virus-host interactions that result in virus-induced demyelination.