Abstract
During the course of an investigation into changes in host-coded enzymes of chick embryo cells (CEC) following infection with Semliki Forest virus (SFV) (Cassells & Burke, 1973) it was observed that, after an initial increase, there was a decrease in the activity of cellular lactate dehydrogenase (LDH: EC 1.1.1.27[EC] ) which coincided with an increase in LDH activity in the growth medium. Further investigation showed that the release of LDH by the cells was an indicator of SFV growth. It was also found that treatment of CE cells with actinomycin D (AMD) resulted in LDH release.
The time course of LDH release is compared in Fig. 1 with other indicators of SFV growth, namely virus RNA synthesis as measured by [3H]-uridine incorporation, virus haemagglutinin production and the release of infective virus.