FIG 3.

Infectious virus production in BHK-21 cells. In vitro-transcribed genomic RNA of the WT and each mutant was transfected into BHK-21 cells. (A) The RNA-transfected cells were analyzed by IFA at 48 h posttransfection, and mouse anti-E monoclonal antibody and rabbit prM antiserum were used as primary antibodies. The viral titer and GCP number of the supernatants collected at each time point posttransfection were quantified by plaque assay (B) and qPCR (C), respectively. (D) The specific infectivities of the WT and the mutants that produced infectious particles were calculated by the ratio of GCPs to infectious particles (GCPs/PFU). Results from one representative experiment out of three independent experiments are shown.