Evaluation of hepatitis C virus envelope proteins expressed in E. coli and insect cells for use as tools for antibody screening.
METHODS
The two envelope proteins of hepatitis C virus, E1 and E2, were expressed in E. coli and, as secretory proteins, in Sf9 insect cells using recombinant baculoviruses. Co-infection of insect cells with E1 and E2-recombinant baculoviruses was performed, which has been shown to result in formation of E1-E2 dimers. All envelope proteins were purified by Ni2+-NTA chromatography and used for screening of serum samples in a HCV EIA assay. Serum samples of normal blood donors, chronically HCV-infected patients, a mixed titer panel and several seroconversion panels were screened and compared to test results with Cobas Core Anti-HCV EIA.


RESULTS
Screening of the sera of chronically HCV-infected patients (100% positive in Cobas Core Anti-HCV EIA) revealed 10-40% anti-E1 positive sera using different Sf9-expressed, glycosylated proteins and 93% using E. coli-expressed, non-glycosylated E1 protein. When the same sera were tested with different E2 proteins expressed in Sf9 cells and in E. coli, about 70-73% showed anti-E2 reactivity. When the proteins from Sf9 cells co-infected with E1- and E2-recombinant baculoviruses were tested, 70-80% of the same sera showed anti-envelope reactivity.


CONCLUSIONS
Testing of these patient antisera, and those from the well-characterized mixed titer panel BBI-PHV203, showed that recombinant E1 expressed in E. coli and co-expressed E1 and E2 proteins from Sf9 cells could be used as additional tools for anti-HCV antibody screening.
Hüssy
P
P
PRP/Gene Technology, F. Hoffmann-La Roche Ltd, Basel, Switzerland.
Faust
H
H
Wagner
J C
JC
Schmid
G
G
Mous
J
J
Jacobsen
H
H
D000818:Animals; D002460:Cell Line; D003001:Cloning, Molecular; D019281:Dimerization; D004926:Escherichia coli; D016174:Hepacivirus / Q000276:immunology*; D006526:Hepatitis C / Q000175:diagnosis* / Q000517:prevention & control; D018937:Hepatitis C Antibodies / Q000097:blood*; D006801:Humans; D007124:Immunoenzyme Techniques; D008403:Mass Screening; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000276:immunology / Q000302:isolation & purification; D012016:Reference Values; D015203:Reproducibility of Results; D018411:Spodoptera; D014162:Transfection; D014759:Viral Envelope Proteins / Q000096:biosynthesis / Q000276:immunology* / Q000302:isolation & purification
C087035:E1 protein, Hepatitis C virus; D018937:Hepatitis C Antibodies; D011994:Recombinant Proteins; D014759:Viral Envelope Proteins; C091015:glycoprotein E2, Hepatitis C virus