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A long-term study of hepatitis C virus replication in non-A, non-B hepatitis
1Hepatitis Viruses Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892.
Background:
Although antibodies to the hepatitis C virus (HCV) are known to be associated with non-A, non-B hepatitis, little is known about the pattern of HCV replication, its relation to antibody levels, and the clinical course of non-A, non-B hepatitis.
Methods:
We measured HCV RNA in serial serum samples from five patients with post-transfusion non-A, non-B hepatitis who were followed for 10 to 14 years after transfusion. We also studied four chimpanzees that were experimentally infected with serum from four of these patients. Serum HCV RNA was detected by a "nested" polymerase-chain-reaction (PCR) assay that used two sets of primers derived from the third (NS3) and fourth (NS4) non-structural gene regions of the HCV genome.
Results:
HCV sequences were detected by PCR in only two of the five patients and two of the four chimpanzees with the set of primers corresponding to the NS3 region, but in all five patients (and in all four chimpanzees) with the primers from the NS4 region. Serum HCV RNA was first detected within three weeks of transfusion in all five patients and within one week in three patients. The viremia lasted less than 4 months in the patient (and two chimpanzees) with acute, self-limited hepatitis, whereas it persisted for 10 to 14 years in the four patients (and for 1 and 3 years in two chimpanzees) with chronic non-A, non-B hepatitis. Antibodies to HCV were first detected at week 12 to 14; they disappeared after nine years in the patient with self-limited disease and became borderline after five years in one of the patients with chronic disease.
Conclusions:
During the early phase of primary HCV infection, there is a period of several months of sero-negativity during which HCV RNA is the only diagnostic marker of infection. The disappearance of HCV RNA from serum appears to correlate with the resolution of non-A, non-B hepatitis, whereas viremia persists in patients whose disease progresses to chronic hepatitis. In contrast, antibody levels do not necessarily remain elevated in patients with chronic disease.