Detection of antibody to hepatitis C virus E2 recombinant antigen among samples indeterminate for anti-HCV after wide serological testing and correlation with viremia. The Spanish Study Group for Blood Donors at Risk of Transmission of HCV.

The detection of antibody to the second envelope protein (E2) of the hepatitis C virus (HCV) has been hampered by the lack of suitable antigens. A previously described E2 recombinant antigen (CHO-E2) expressed as a non-fused, highly glycosylated protein in mammalian cells was used to detect specific antibody (anti-E2) in samples from blood donors and viraemic patients showing positive or indeterminate results for anti-HCV after a wide serological study. Anti-E2 was detected in 50-75% of the donors positive for anti-HCV, 80% of viraemic immunocompetent patients with anti-NS3 alone and 28% of non-viraemic donors with anticore alone. In donors with anti-NS3 (15 samples) or anti-NS4 (51 samples) alone, anti-E2 was found occasionally (3 cases). Moreover, two anti-E2-positive samples from viraemic patients were misidentified by some commercial assays for screening anti-HCV. These results suggest that testing for anti-E2 may be useful for improving the performance of the current assays for anti-HCV screening and confirmation.

[Comparative sensitivity of different solid-phase immunoassays for detecting HBsAg and anti-HCV in blood]. / Sensibilidad comparativa de distintos inmunoensayos en fase sólida para detección de HBsAg y anti-VHC en suero.

The sensitivities of seven methods of enzyme-immunoassay for HBsAg detection, as well as of twelve immunoassays for detecting antibody to HCV, were compared, in an attempt to evaluate the need for an official technical validation of such methods prior to its commercialization in Spain. Significant differences were seen for the sensitivities of these methods, which may influence the proficiency of blood bank screening for HBsAg and anti-HCV for preventing cases of post-transfusional viral hepatitis. As a conclusion, it is recommended to establish legal regulations for pre-marketing validation of such assays in Spain, as well as to take the results obtained in these evaluation studies as the basis for selecting those tests which may be more convenient for screening purposes at the blood banks.

Screening of antibodies to varicella-zoster virus in leukemic patients: comparison of commercial methods of enzyme-immunoassay and fluoroimmunoassay.

Commercial methods of enzyme immunoassay and fluoroimmunoassay for the detection of varicella-zoster antibodies were compared using serum samples from individuals in a program of bone marrow transplantation. The correlation was 93.4%. Enzyme immunoassay showed to be more sensitive. Both methods are applicable to the detection of varicella-zoster antibodies. However, when fluoroimmunoassay is used, we recommend the confirmation of negative results by a sensitive enzyme immunoassay.