Fig. 3.

Expression of SARS-CoV proteins by BHPIV3 vectors. LLC-MK2 cells were infected with the individual BHPIV3 vectors (lanes 1-7) at an input multiplicity of infection of 5 TCID₅₀ per cell. In addition, Vero cells were mock-infected (lane 9) or infected with 5 TCID₅₀ per cell of SARS-CoV (lane 8). Cell lysates were prepared 42 h after infection, in the case of SARS-CoV, or 72 h after infection, in the case of the BHPIV3 vectors, denatured under reducing conditions, subjected to SDS/PAGE in 4-12% gradient gels, and transferred to nitrocellulose. SARS-CoV proteins were detected by using convalescent serum from an African green monkey that had been infected with SARS-CoV. The BHPIV3 F protein was detected in a parallel blot by using HPIV3-specific rabbit hyperimmune serum (Lower). Detection of bound antibodies was done with horseradish peroxidase-conjugated goat anti-human (in the case of the anti-SARS-CoV serum) or anti-rabbit (in the case of the anti-HPIV3 serum) antibody, respectively, and visualized by chemiluminescence.