Tj. Pilotmatias et al., EXPRESSION OF THE GB VIRUS-C E2 GLYCOPROTEIN USING THE SEMLIKI-FOREST-VIRUS VECTOR SYSTEM AND ITS UTILITY AS A SEROLOGIC MARKER, Virology, 225(2), 1996, pp. 282-292
A 336-amino-acid segment of the GB virus C second envelope protein (E2
) has been produced in BHK-21 cells using the Semliki Forest virus vec
tor system. Secretion of this protein was facilitated by deletion of a
hydrophobic region at the C-terminus that may represent the membrane
anchoring domain. The E2 protein recovered from the culture supernatan
t exhibited a molecular mass of approximately 52 kDa, with the increas
e in size relative to the polyprotein backbone being contributed by N-
linked glycosylation. A radioimmunoprecipitation assay using GBV-C E2
was developed to test for the presence of antibodies against this prot
ein in human sera. The prevalence of antibodies to E2 was high among i
njection drug users and other individuals at risk for acquiring parent
erally transmitted agents. There was a much higher percentage of anti-
E2 seropositivity in GBV-C RT-PCR negative compared to GBV-C RT-PCR po
sitive samples from these populations. In addition, serial samples fro
m patients transfused with blood containing GBV-C showed seroconversio
n to anti-E2 positivity and loss of GBV-C viremia as measured by RT-PC
R within 11 months of transfusion in five of seven individuals. Thus,
this system provided a rapid means to identify GBV-C E2 as a useful an
tigen for the study of GBV-C exposure. (C) 1996 academic Press, Inc.