Hepatitis C virus serological and polymerase chain reactions in human immunodeficiency virus-positive and -negative patients

Rapid changes in hepatitis C virus quasispecies produced by a single dose of IFN-alpha in chronically infected patients

The effects of a single dose of 3 international megaunits of interferon-alpha2b (IFN-alpha2b) on hepatitis C virus (HCV) load and quasispecies were examined 24 h after administration in 12 previously untreated, chronically infected patients. All patients had viremia loads appreciably reduced relative to baseline values, thus confirming that the viral load is rapidly affected by IFN-alpha2b. Five patients also exhibited changes in plasma HCV quasispecies composition that were clearly evident by single-strand conformation polymorphism, analysis, thus indicating that one dose of IFN-alpha2b may suffice to produce rapid perturbations in the genetic heterogeneity of circulating HCV. Prior to IFN-alpha2b administration, 3 patients exhibited viral quasispecies differences between plasma and peripheral blood mononuclear cells (PBMC). Interestingly, in 2 such patients, the viral quasispecies found in the 24-h plasma resembled that in the pre-IFN PBMC. The latter finding raises the possibility that in these patients, the differences in quasispecies composition between pre-IFN and post-IFN plasma resulted from increased representation of lymphoid tissue-originated variants in the latter sample, possibly because of poor sensitivity to IFN-alpha2b of HCV replication in the lymphoid compartment.

Susceptibility of human and non-human cell lines to HCV infection as determined by the centrifugation-facilitated method

The centrifugation-facilitated inoculation method was used to test 51 human and non-human cell lines for ability to support HCV replication. As determined by nested RT-PCR, one fifth of the cell lines tested were virus positive 15 days post inoculation suggesting that the centrifugation-facilitated inoculation is an efficient method for cell infection with HCV. However, virus production by infected cultures remained of low grade, thus showing that the unknown factors which limit HCV replication in vitro are not overcome by the procedure.

Comparative evaluation of five rapid methods for identifying subtype 1b and 2c hepatitis C virus isolates

A panel of 61 HCV isolates belonging to five different subtypes were used to evaluate five methods for rapid typing of HCV RNA: an in-house type-specific polymerase chain reaction based on the core region (type-specific PCR), a commercial amplification of the core region followed by hybridisation to probe coated wells (DEIA), a commercial amplification of the 5'-UTR region followed by hybridisation to probes immobilised on strips (LiPA), an in-house restriction fragment polymorphism analysis of the 5'UTR (RFLP), and a commercial serological method using synthetic peptides from the NS4 region (serotyping). The correct viral type was identified in 90% of cases by DEIA, in 82% of cases by type-specific PCR, in 80% of cases by LiPA and RFLP, and in 67% of cases by serotyping. Correct identification of the virus subtype was much less frequent and was beyond the performance characteristics of some assays. Major problems were found in the identification of isolates belonging to type 2. This was probably at least partly due to the fact that all type 2 isolates in the viral panel were of subtype 2c, which has been considered rare until recently.

Subtype 2c of hepatitis C virus is highly prevalent in Italy and is heterogeneous in the NS5A region

Hepatitis C virus (HCV) isolates, obtained from 50 Italian patients with community-acquired infection, that had previously been classified as subtype 2a or 2b by current rapid genotyping methods were further characterized by partial sequence analysis. All the isolates were reclassified: 45 within subtype 2c and the other 5 as subtype 1b, 3a, or 4d. Thus, subtype 2c is much more prevalent than previously recognized, with about 30% of all HCV strains detected in Italy being subtype 2c. In contrast, isolates of subtypes 2a and 2b appear to be infrequent, if not absent. Further studies showed that subtype 2c isolates are heterogeneous in the NS5A region, in that they may or may not contain a 57-nucleotide (nt) segment spanning from nt 7533 to nt 7589 of the viral genome. Partial nucleotide sequencing of the NS5B region of four 2c subtypes excluded the possibility that the isolates possessing or not possessing the 57-nt segment in the NS5A region may have resulted from recombination phenomena.

Partial nucleotide sequencing of six subtype 2c hepatitis C viruses detected in Italy

The great majority of 121 hepatitis C virus (HCV) isolates obtained from 117 Italian patients with community-acquired infection could readily be typed by genotype-specific PCR. Subtype 1b was dominant (74 isolates); subtypes 2b, 2a, and 1a followed, with 19, 14, and 8 isolates, respectively. The six isolates that remained untyped by this method were classified as subtype 2c on the basis of sequence analysis of PCR amplicors obtained from the core and NS5 genes. These findings indicate that HCV subtype 2c has a relatively high prevalence in Italy. Sequencing the core region from positions 160 to 259 is sufficient to distinguish subtype 2c from other known HCV genotypes.

Serological reactivity and viral genotypes in hepatitis C virus infection

Patients infected with hepatitis C virus (HCV) were examined with four commercial HCV immunoblotting assays and for anti-GOR antibody to ascertain whether serological findings varied with the genotype of the infecting virus. The results indicate that patients infected with different HCV genotypes tend to show different immunoblotting profiles, mainly due to a low prevalence of antibodies to the viral region NS4 in patients infected with genotypes III and IV. Differences were more evident with second- than with third-generation assays. Patients infected with genotype IV exhibited a lower prevalence of anti-GOR antibody than patients infected with other genotypes.