Human monoclonal antibodies for the immunological characterization of a highly conserved protein domain of the hepatitis C virus glycoprotein E1.

Although both envelope glycoproteins of the hepatitis C virus, E1 and E2/NS1, show a high degree of sequence variation, the E1 protein includes a well conserved domain, which may be functionally important. We have analysed the human B cell response to a peptide fragment from amino acid residues 314-330 (EP3) covering the central conserved sequence of this domain. Anti-hepatitis C virus-positive blood donors were screened for anti-EP3 antibodies with an ELISA based on immobilized peptide. Thirty out of 92 (32%) RIBA-confirmed donors displayed a significant antibody response to EP3. From three of these blood donors we established four anti-EP3-producing heterohybridoma cell lines: Ul/F30 and Ul/F31 produced IgM-kappa, whereas Ul/F32 and Ul/F33 secreted the isotypes IgG1-lambda and IgG1-kappa, respectively. Epitope analysis with overlapping nonapeptides suggests the existence of different antigenic determinants within the EP3 fragment. Although both IgG antibodies Ul/F32 and Ul/F33 have dissociation constants to the peptide of approximately 10(-9) M, binding to recombinant E1 protein expressed in COS-7 cells was different. Only Ul/F33 detected envelope protein of approximately 24-35 kD in Western blot. This human MoAb will be useful for further investigations on the hepatitis C virus glycoprotein E1.

Investigating the presence of HIV sequences and the distribution of virological markers in hemophiliacs and their sexual partners.

In this study, we report the investigation of a hemophiliac cohort, in which the last HIV-1 seroconversion occurred in 1985. We wanted to evaluate whether 5 years later the results of serological screening and polymerase chain reaction (PCR) technology would match. We examined 61 German patients with congenital deficiencies of factors VII, VIII-c, and IX, and 16 sexual partners (15 partners of anti-HIV-1-negative hemophiliacs). Patients' and partners' anti-HIV-1 status was determined by ELISA and Western blot. Further, we applied the PCR to investigate the possible presence of HIV sequences in anti-HIV-1-negative individuals. Four sets of primers were used in four separated reactions to avoid false-negative results due to genetic variation, as well as false-positive results due to DNA carryover. The data by PCR were not different from the data attained by conventional serological methods. The prevalence of serological markers for HBV and HCV was determined.