Detection of Divergent Hepatitis C Virus Envelope Sequences

Superinfection by homotypic virus in hepatitis C virus carriers: studies on patients with post-transfusion hepatitis

Although heterotypic superinfection and mixed infections of hepatitis C virus (HCV) may be possible for hepatitis flares in chronic hepatitis C, the possibility of homotypic HCV superinfection in HCV carriers with post-transfusion hepatitis has not been explored. Six HCV carriers with post-transfusion non-A, non-B hepatitis found in a prospective study of post-transfusion hepatitis were included. Serum samples before transfusion and during hepatitis were selected to determine genotypes of HCV and nucleotide sequences of the hypervariable region (HVR). The genotypes identified before and after transfusion were concordant in all. There were four with type 1b and one each with type 2a and type 2b. Amplified nucleotide sequences of the HVR before transfusion and during hepatitis were compared in four patients, and a > 95% homology was observed in three, suggesting persistence of original viruses. In contrast, only a 51% homogeneity was seen in a given patient, suggesting a homotypic HCV superinfection. Phylogenetic tree analysis validated further these findings. This study implies that HCV carriers can be reinfected by homotypic HCV, and this may contribute to hepatitis flares in chronic hepatitis C. These findings also confirm a weak or inadequate protective immunity in HCV infection and justify protection from reinfection of HCV of patients with chronic hepatitis C.

Serotyping of hepatitis C virus in chronic type C hepatitis in Taiwan: correlation with genotypes

To evaluate the usefulness of a new serologic assay to group hepatitis C virus (HCV), genotypes identified by this serotyping method were compared to those identified by a polymerase chain reaction (PCR) assay with type-specific primers in 71 Taiwanese patients with chronic type C hepatitis. The group-specific antibodies against different HCV genotypes were detected by using an enzyme-linked immunosorbent assay (ELISA) based on group-specific recombinant peptides (C14-1 and C14-2) within the NS4 region. Among 71 patients positive for current second-generation HCV antibodies, HCV RNA was detected in 55 patients by PCR with primers from the 5' untranslating region, and in 52 by genotype-specific PCR. In 49 (89%) of 55 viremic patients, the results of serotyping by ELISA showed complete agreement with those determined by PCR genotyping, and none of the patients showed a group opposite to that of HCV genotype. The positive rate of group-specific antibodies (69/71;97%) was even better than that of the PCR (55/71;78%). We conclude that this new serotyping assay is highly sensitive and specific for the determination of HCV genotypes, and will be useful in future epidemiologic studies, as well for clinical application.

Prevalence, genotypes and antibody titer of hepatitis C virus in pregnant women in Taiwan

OBJECTIVES

To investigate the prevalence and genotypes of hepatitis C virus (HCV) in pregnant women in Taiwan, as well as to examine whether any correlation occurs between HCV genotype and anti-HCV titer.

METHODS

Forty-three pregnant women with positive anti-HCV and HCV-RNA were selected among 3,400 cases screened from January 1992 to March 1994. Each blood specimen was assayed for HCV genotypes by PCR method to detect HCV I, II, III and IV. Anti-HCV titer was determined by a second-generation EIA kit with serial dilutions.

RESULTS

Twenty-eight cases (65%) belonged to HCV II, 11 (26%) HCV III, 3 (7%) HCV IV and 1 (2%) HCV II+III. Besides, the anti-HCV titers in HCV II and HCV III groups were similar, ranging from 8x to 40,000x and revealing no statistical significance (p = 0.75).

CONCLUSIONS

Our data have verified that the prevalence rate of HCV infection in pregnant women is around 1.3% and no significant difference of anti-HCV titer occurs between HCV II and HCV III pregnant women.