FIG. 2.

RT-PCR screening of clinical samples from suspected SARS patients. The upper bands in each row show a 745-bp DNA fragment amplified with actin F and actin R, while the lower bands are the amplicons by primers specific to the N gene of SARS-CoV (225 bp). cDNA samples synthesized from total RNAs extracted from NPA samples (A1 to H1) were used as templates in both N-gene-specific and β-actin-specific PCRs. The negative control (water) and positive control (cDNA from SARS-CoV-infected Vero cells) for the assay are indicated. Five-microliter samples of PCR products from two separate reactions, i.e., N-gene-specific PCR and β-actin-specific PCR, were mixed and loaded into the same well in a 2% agarose gel. M, 1 kb Plus molecular marker (Invitrogen).