Enzyme-linked immunosorbent assay for antibodies against the capsid protein of hepatitis C virus with a synthetic oligopeptide.
An enzyme-linked immunosorbent assay was developed for the determination of antibodies against the putative capsid protein of hepatitis C virus (HCV). A 36-mer oligopeptide with a sequence of RRGPRLGVRATRKTSERSQPRGRRQPIPKVRRPEGR (CP9) was synthesized; it was selected on the translation product of the presumptive HCV core gene, because of a high local hydrophilicity and excellent conservation by different HCV strains. The synthetic peptide was immobilized on a solid-support to capture antibodies directed to CP9 (anti-CP9) in test sera, which were detected by Fab' fragments of monoclonal anti-human IgG/gamma labeled with horseradish peroxidase. The specificity of anti-CP9 was confirmed by absorption tests. Anti-CP9 was detected in 13 (68%) of 19 patients with sporadic acute non-A, non-B (NANB) hepatitis and in 15 (83%) of 18 patients with post-transfusion acute NANB hepatitis. In 7 cases of acute NANB hepatitis who were followed, anti-CP9 developed earlier than antibodies against HCV (anti-HCV) detectable by a commercial assay kit. Among patients with chronic NANB liver diseases, anti-CP9 was detected in 103 (77%) of 133 with chronic hepatitis, 70 (62%) of 113 with liver cirrhosis and 31 (76%) of 41 with hepatocellular carcinoma. Anti-CP9 and anti-HCV overlapped in 175 (54%) among 324 cases of acute or chronic NANB liver diseases; 58 (18%) were positive only for anti-CP9 while 49 (15%) were positive only for anti-HCV. HCV RNA was detected, by amplifying HCV cDNA with polymerase chain reaction, in 10 of 11 sera positive only for anti-CP9. Among sera from 606 blood donors, 21 were positive only for anti-CP9. HCV RNA was detected in 5 (24%) of them, all of which had A492 values greater than 0.600 in ELISA for anti-CP9. Based on these results, anti-CP9 would complement anti-HCV for the diagnosis of HCV infection and contribute toward further decreasing posttransfusion NANB hepatitis.
Okamoto
H
H
Immunology Division, Jichi Medical School, Tochigi, Japan.
Munekata
E
E
Tsuda
F
F
Takahashi
K
K
Yotsumoto
S
S
Tanaka
T
T
Tachibana
K
K
Akahane
Y
Y
Sugai
Y
Y
Miyakawa
Y
Y
D000595:Amino Acid Sequence; D001782:Blood Donors; D002213:Capsid / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D016174:Hepacivirus / Q000235:genetics / Q000276:immunology*; D006508:Hepatitis Antibodies / Q000097:blood*; D006526:Hepatitis C / Q000276:immunology* / Q000382:microbiology; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012367:RNA, Viral / Q000097:blood
D006508:Hepatitis Antibodies; D012367:RNA, Viral