SARS-CoV neutralizing activity of Sera. Mice were immunized three times with rADV-S 2 × 107 PFU by s.l., i.n., or i.m. route. Sera were tested to measure the Abs that would neutralize the infectivity of 100 TCID50 of SARS-CoV in Vero cell monolayers. Neutralization titers were determined by the CPE of SARS-CoV on Vero cell. The dotted line indicates the limitation of detection. The results are expressed as the means + SD.