Epstein–Barr virus (EBV) typing of normal individuals and patients with systemic lupus erythematosus (SLE) in mouthwash samples. (a) PCR/Southern blot of the EBV nuclear antigen (EBNA)-3C encoding region for the cell lines carrying type 1 (ES-1, B95-8, LCL2, and Namalwa) and type 2 (SNU-99 and AG876) EBV. DNA extracted from each EBV infected cell line (5 ng) was subjected to EBNA-3C-specific PCR/Southern blot. PCR amplified products were transferred to a membrane and hybridized with an EBNA-3C probe common to both type 1 and type 2 EBV. The expected PCR product sizes were 153 bp for type 1 EBV and 246 bp for type 2 EBV. The EBV negative cell line BJAB and distilled water served as negative controls. (b,c) PCR/Southern blot of the EBNA-3C encoding region for the DNA from mouthwash samples. One 20th of the DNA isolated from mouthwash samples was used for each PCR reaction. Representative results obtained from normal controls (panel b) and SLE patients (panel c) are shown. Namalwa and AG876 were used as positive controls for type 1 and type 2 EBV, respectively. Distilled water (dH20) and DNA isolated from BJAB were used as negative controls.