Analysis of HCV-IG isotype complexes by a novel immuno-capture RT-PCR method

HCV can be present in the circulating blood either as a free virus or as a virion-immunoglobulin (Ig) complex. All isotypes of Igs may form the virus complexes, but it remains unclear what specific role of each Ig plays in the clearance of HCV. In the present study, we have combined immuno-capture and RT-PCR, and developed a quick double-specificity method for detecting and distinguishing different HCV-Ig complexes. We compared our new method, the immuno-capture RT-PCR (iRT-PCR), with the conventional RT-PCR (cRT-PCR) for the sensitivity of detecting HCV in 35 clinically diagnosed patients with HCV infection. The results showed that 31 patients were detected to be positive by using iRT-PCR, whereas 16 patients were positive with the use of cRT-PCR. HCV-IgM, HCV-IgG, HCV-IgA could separately be detected by iRT-PCR and their positive rates were 66.7%, 51.0%, 62.7%, respectively. HCV bound to antibody was a common feature of hepatitis C (HC) and 86.3% of patients were positive at least by one of the HCV-Ig tests. The patterns of HCV RNA constituents varied according to disease categories. In summary, iRT-PCR is a valuable method for analysis of the composition of the immune complexes, which may provide new and valuable insights into HCV pathogenesis.