Fig. 4.

Viral replication levels in the respiratory tracts of SARS-CoV-infected African green monkeys and macaques. (A and B) SARS-CoV replication in the throats (A) and noses (B) of SARS-CoV-infected African green monkeys (black bars) and macaques (white bars) at days 2 and 4 postinfection as determined by real-time RT-PCR. Viral-RNA levels are displayed as TCID₅₀ equivalents (eq.)/ml swab medium (plus SEM). (C) Average fold change in SARS-CoV mRNA levels (plus SEM) in the lungs of African green monkeys and macaques compared to PBS-infected animals as determined by real-time RT-PCR and depicted on a log scale. In addition, SARS-CoV titration of lung homogenates is shown in TCID₅₀ per gram lung tissue. (D) Quantitative assessment of SARS-CoV-infected cells in the lungs of African green monkeys and macaques depicted as a percentage of SARS-CoV-positive fields (plus SEM).