FIG. 4.
IFN-α-inducing activity of recombinant pseudoparticles and TGEV virions. Purified recombinant particles and virions were obtained as described in Materials and Methods. Based on the results of an ELISA, the suspensions were adjusted to have approximately the same M antigen content and then incubated with PBM cells at the indicated dilutions. The blocking effect of anti-M MAb 25.22 on IFN induction is shown on the right. The ratio of virions to PBM cells was estimated to be 100 ng per 2 × 105 cells at the 1/100 dilution.