Division 3

If a cytopathic effect develops, the supernatant fluid must be harvested from positive cultures when the effect is complete and used in the ELISA for virus identification. Negative cultures must be inoculated on fresh tissue cultures at 48 or 72 hours and this blind passage examined up to 72 hours later. In the absence of cytopathic effect after a further blind passage the sample can be declared negative for the presence of live virus.