Mean levels of serum neutralizing antibody to SARS-CoV.

<p>Neutralizing antibody levels in serum were determined as outlined in the materials and methods section. Inverse neutralization titre is represented on the y-axis vs. day of study on the x-axis. Note that ferrets were infected on study day 1 and reinfected ferrets were also innoculated on study day 30. Mock infected animals received an intranasal instillation of serum-free media on study day 1 and had undetectable titres. Values shown represent group mean of 3–4 ferrets per group, and error bars show standard deviation.