T. Fujisawa et al., Influence of RNA titre and amino acid changes in the NS5A region of GB virus C hepatitis G virus on the effectiveness of interferon therapy, J GASTR HEP, 15(6), 2000, pp. 632-639
Background: A relationship between the pretreatment RNA titre of GB virus C
/hepatitis G virus (GBV-C/HGV) and the effectiveness of interferon (IFN) th
erapy has been reported previously. However, the influence of changes in th
e amino acid sequence of the NS5A region of GBV-C/HGV on the effectiveness
of IFN therapy has not been examined, although this influence has been expl
ored in patients with chronic hepatitis caused by hepatitis C virus. We exa
mined the relationship between changes in the amino-acid sequence of the NS
5A region and the effectiveness of IFN therapy.
Methods: The subjects were 10 patients with chronic hepatitis C coinfected
with GBV-C/HGV and treated with IFN. The pretreatment level of GBV-C/HGV-RN
A (copies/mL) in their sera was measured by real-time detection polymerase
chain reaction (PCR) assay. At 6 months after cessation of therapy, four of
10 patients had become negative for GBV-C/HGV-RNA (CR, complete response)
and six patients were still positive for GBV-C/HGV-RNA (NR, non-response).
We determined the nucleotide sequence of the NS5A region (amino acid residu
es 1865-2279; NS5A(1865-2279)) of pretreatment GBV-C/HGV-RNA by direct sequ
encing.
Results: The pretreatment GBV-C/HGV-RNA level of CR patients (7.8 x 10(4)-6
.2 x 10(5), mean 3.30 x 10(5)) was significantly lower than that of NR pati
ents (6.3 x 10(7)-7.2 x 10(8), mean 3.55 x 10(8); P < 0.01). The number of
amino acid substitutions in NS5A(1865-2279) was five to seven (mean 5.8 +/-
1.0) in CR patients, and four to eight (mean 6.8 +/- 1.6) in NR patients,
a difference that is not significant. Moreover, there were no amino acid su
bstitutions or sites of substitution in NS5A(1865-2279) that were specific
to either group.
Conclusions: The effectiveness of IFN therapy for GBV-C/HGV is strongly rel
ated to the pretreatment GBV-C/HGV-RNA level, but is not related to changes
in NS5A(1865-2279). (C) 2000 Blackwell Science Asia Pty Ltd.