Demyelinating, non-demyelinating and attenuated canine distemper virus strains induce oligodendroglial cytolysis in vitro.

A virulent canine distemper virus (CDV) strain that causes demyelination in vivo has been shown to induce oligodendroglial degeneration in vitro. In order to investigate if this effect on oligodendrocytes is specific for demyelinating strains only, primary brain cell cultures were infected with either virulent demyelinating strains (A75/17 and CH84-CDV), a virulent non-demyelinating strain (SH-CDV) or a non-virulent strain (OP-CDV). All virulent viruses caused a persistent type infection with moderate cytolysis whereas the non-virulent strain was highly cytolytic. All strains induced a similar pattern of oligodendroglial degeneration. It was concluded that the ability to induce oligodendroglial degeneration, which is thought to be the in vitro correlate of demyelination in vivo, is inherent to CDV irrespective of the strain. The discrepancy between biological behaviour of CDV strains in brain cell cultures and in vivo can be explained by the more complex virus-cell interactions in vivo than in vitro.