Through infection of L-929 cells with the DA-strain of Theiler's Murine Encephalomyelitis Virus (TMEV) and incubation of the samples at different temperatures, we studied the effect of the temperature (30^C, 32^C, 34^C, 36^C and 37^C) on the assembly of this virus. The infected cells were lysed at different times and subjected to sucrose gradient ultracentrifugation and immunoprecipitation to study what kind of particles (qualitative effect) we obtained. When possible, we determined the amount of viral particles (quantitative effect). From these experiments we found that higher temperatures were more degenerative then lower temperatures, although too low temperatures were not productive either: at 30^C there were no virions detectable at all, no matter at what time post-infection we lysed the cells. Because in the literature most experiments on the TMEV are performed at 37^C, we expected to find the highest amount of virions at that temperature. Though it was at 34^C that the hightest amount of virions was generated. This means that replication is more efficient at 34^C then at 37^C. A second indication for this higher efficiency at lower temperatures can be found in the rapid decrease in virion production at 32^C. This also reflects the sensitivity of the replication of this virus to different temperatures.
Although the amount of virions was greater at 34^C then at 37^C, the 14S material generated at 34^C was less then the amount generated at 37^C. SDS-PAGE revealed that these 14S particles weren't intermediates of the viral assembly process but degradation particles formed at higher temperatures. We found more degradation material at 37^C compared to 34^C. To our surprise no peaks of 5S protomers and 14S pentamers were detectable at 7 h. post-infection. At 10 h. post-infection, only 5S protomers were detectable. We concluded that the absence of these 14S pentamers was due to faster assembly of 14S pentamers into mature virions, because we also detected virions at that time.