Table 1.

Repertoire analysis of IgG memory B cells

Months after infection	Positive cultures/total cultures screened (%)a
	ELISA	Spike-staining
2	275/480 (57.3%)	ND
4	123/480 (25.6%)	12/576 (2.1%)
6	44/480 (9.2%)	21/768 (2.7%)
8	20/480 (4.1%)	94/3,102 (3%)

^aFraction of cultures screening positive in the SARS-CoV ELISA or staining SARS-CoV spike transfectants at different time points after infection. IgG⁺ memory B cells were cultured at 10 cells per well in the presence of EBV and CpG 2006. Culture supernatants were analyzed after 2 weeks. There was no overlap between cultures screening positive by either assay, indicating that the assays detect distinct antibody specificities. SARS-CoV was not detectable in culture supernatant or in EBV-B cells, as determined by cytopathic assay on Vero cells and by RT-PCR (data not shown). ND, not determined because the assay was not available at the time of the analysis.