Expression of hepatitis C virus hypervariable region 1 and its clinical significance.
OBJECTIVE
To explore the properties of hypervariable region 1 (HVR1) in the envelope 2 gene of hepatitis C virus by analyzing the reactivity of HVR1 fusion proteins from different Chinese HCV strains with sera of patients with chronic hepatitis C and by comparing their reactivity between interferon therapy responders and non-responders.


METHODS
Gene fragments of HVR1 of four HCV strains (three genotype 1b and one genotype 2a) were amplified from pGEMT-E2 plasmids and sub-cloned into pQE40 vectors respectively to construct recombinant expression plasmids which expressed HVR1 fused downstream to DHFR in Escherichia coli strain TG1. The purified DHFR- HVR1 proteins were then used to detect the anti-HVR1 antibodies in 70 serum samples of patients with chronic hepatitis C.


RESULTS
Four DHFR- HVR1 fusion proteins were successfully expressed in E.coli (320-800 ug fusion proteins per 100 ml culture). Each fusion protein (SH1b, BJ1b, SD1b and SD2a) reacted with 72.8 % (51/70), 60 % (42/70), 48.6 % (34/70), and 58.6 % (41/30) of the anti-HCV positive patients' sera respectively by ELISA. 57 % (4/7) of non responders reacted with all four HVR1 fusion proteins, while only 15.3 % (2/13) of responders reacted with all of them. The O.D. values of sera from IFN therapy responders were significantly higher than those of non responders (P<0.05).


CONCLUSIONS
The selected HVR1 fusion proteins expressed in E. coli can broadly react with HCV-infected patients' sera. The intensity and/or quality of the immune response against HCV may be a critical factor determining the response to interferon treatment. With the evolution of virus strains, anti-HVR1 antibodies can not neutralize all the quasispecies. A polyvalent and high immunogenic vaccine comprising a mixture of several HVR1 sequences that cover the reactivity of most HCV isolates may be useful.
Zhang
Xin-Xin
XX
State Key Laboratory of Molecular Biology, Shanghai, China.
Zhang
Shen-Ying
SY
Liu
Jing
J
Lu
Zhi-Meng
ZM
Wang
Yuan
Y
D000328:Adult; D001483:Base Sequence; D002681:China; D004279:DNA, Viral / Q000235:genetics; D005260:Female; D005814:Genes, Viral; D014644:Genetic Variation; D016174:Hepacivirus / Q000235:genetics* / Q000276:immunology; D018937:Hepatitis C Antibodies / Q000097:blood; D019698:Hepatitis C, Chronic / Q000188:drug therapy / Q000276:immunology / Q000821:virology*; D006801:Humans; D007372:Interferons / Q000627:therapeutic use; D008297:Male; D010957:Plasmids / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D011995:Recombination, Genetic; D014764:Viral Proteins / Q000235:genetics* / Q000302:isolation & purification
D004279:DNA, Viral; C400562:HVR1 protein, Hepatitis C virus; D018937:Hepatitis C Antibodies; D011993:Recombinant Fusion Proteins; D014764:Viral Proteins; D007372:Interferons