We developed a series of oligonucleotide primers capable of detecting, typing, and subtyping influenza virus type A (H1 and H3) and type B and respiratory syncytial viruses types A and B. RNAs were isolated from culture fluid or clinical specimens, and cDNA synthesis and PCR were carried out with mixtures of primers specific to each virus. Amplified products were detected by ethidium bromide staining of amplified products after agarose gel electrophoresis. For each virus, five amplified products of different sizes could be distinguished on agarose gels. Multiplex RT-PCR can also be used to detect more than one viral template in the same reaction mixture, allowing identification of multiple strains in the same specimen.

The prevalence of anti‐HCV antibodies in Chinese patients with HBsAg‐negative chronic liver diseases was studied retrospectively. Anti‐HCV was detected by two different ELISAs. In 97 pa‐ tients with HBsAg‐negative chronic liver disease, 26 (27%) were anti‐HCV positive. Of 157 control subjects, only 1 (0.6%) was anti‐HCV positive (P < 0.001). Anti‐HCV was detected in 18 of 27 (67%) patients with post‐transfusion non‐A, non‐B (PTNANB) chronic hepatitis or cirrhosis, 5 of 25 (20%) patients with cryptogenic chronic hepatitis or cirrhosis, 2 of 33 (6%) patients with alcoholic liver disease, 1 of 5 (20%) patients with autoimmune chronic active hepatitis (AICAH), none of 4 patients with primary biliary cirrhosis (PBC), and none of 3 patients with fatty liver. The prevalence in this group of patients was lower when compared to reports from other countries. The addition of a urea washing step reduced false‐positivity in alcoholic and AICAH groups. The ELISA that employs three recombinant HCV antigens confirmed all positive results by an‐ other ELISA with the exception of one weakly positive result in the AICAH group and one in the alcoholic group. One patient in the PTNANB group was detected in addition by the second generation assay. In conclusion, ELISA with a urea wash proved to be useful in reducing falsepositivity, and the second generation assay proved to be a sensitive and specific test for anti‐HCV antibody. © 1992 Wiley‐Liss, Inc.