Figure 2.

Induction of humoral and cellular immune responses against SARS-CoV-N. (A) Identification of SARS-CoV nucleocapsid-specific antibodies in sera of MV-N immunised mice by immunoblots. Lysates from S2 Drosophila cells expressing SARS-CoV-N or from wild type S2 cells were separated by SDS-PAGE and proteins were blotted onto Immobilon-P membranes. Pieces of identical membranes were incubated with the monoclonal anti-V5 antibody, with human convalescent anti-SARS serum, with rabbit anti-SARS N (548) or with sera from immunised mice (as indicated). (B) Characterisation of SARS-CoV-N specific T cells from mice immunised with MV-N by IFN-γ ELISPOT assays. Splenocytes were taken from mice 3 weeks after a single immunisation with 10⁵ pfu MV-N, MV-HIV-p17/24 (as a recombinant negative control) or MV (as standard control). Splenocytes were stimulated either with purified nucleocapsid fusion protein (S2-N/V5-His), a similar extract from wild type S2 cells (S2) or with medium only. All experiments were done in triplicates.