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Characterization of hepatitis C virus structural proteins with a recombinant baculovirus expression system
Author(s) -
Hsu Henry H.,
Donets Mikhail,
Greenberg Harry B.,
Feinstone Stephen M.
Publication year - 1993
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.1840170503
Subject(s) - capsid , virology , recombinant dna , microbiology and biotechnology , biology , hepatitis c virus , virus , antibody , hepatitis b virus dna polymerase , viral envelope , gene , biochemistry , immunology
We cloned and expressed the sequences encoding the structural proteins of the hepatitis C virus in a baculovirus eukaryotic expression system. Four recombinant constructs expressed sufficient hepatitis C virus–specific proteins in insect cell culture to allow analysis of protein cleavage, glycosylation and immunoreactivity. Using immunoblot analysis, we detected a 22‐kD protein corresponding to the hepatitis C virus capsid protein cleaved from a larger precursor. Recombinant constructs encoding the presumptive envelope (E1) protein produced products ranging from 30 to 35 kD, whereas constructs encoding the presumptive E2/NS1 protein expressed products ranging in size from 68 to 73 kD. The recombinant envelope proteins were glycosylated, as shown by sensitivity to endoglycosidase F digestion, whereas the capsid was not. We examined the immunoreactivity of these recombinant proteins using sera from 50 patients chronically infected with HCV. Forty‐seven of 50 of these sera contained antibodies against the capsid, 14 (28%) also had antibodies against E1 and at least 5 (10%) had antibody against E2/NS1. Forty‐seven of 50 sera (94%) were viremic, as determined on hepatitis C virus polymerase chain reaction. The three sera that were hepatitis C virus polymerase chain reaction negative did not have envelope antibodies, whereas all sera that had envelope antibodies were also hepatitis C virus polymerase chain reaction positive. Thus antibodies to baculovirus‐expressed hepatitis C virus structural proteins, including E1 and E2/NS1, are found in the presence of viremia. (H EPATOLOGY 1993;17:763–771.)