Immune responses to two recombinant envelope 2 (E2) proteins, representing
genotypes 1 and 2 of the GB virus C, or the hepatitis G virus (GBV-C/HGV),
were studied in mice and in 48 individuals with, or without, chronic, or pa
st GBV-C/HGV infection. Immunised mice developed E2-specific antibodies (me
an titres, 1:1,167 to 1:9,360), recognising linear antigenic regions and pr
oliferative and IL-2, IL-6 and gamma IFN cytokine responses regardless of t
he viral genotype. Individuals with past GBV-C infection had E2 antibody ti
tres from 1:1,500 to 1:7,500 that did not recognise the E. coli derived E2
protein or linear antigenic regions. Proliferative E2-specific responses we
re detected in peripheral blood mononuclear cells from 6/22 (27%) persons w
ith, and in none without GBV-C markers (P < 0.05). Thus, E2-specific immune
responses are mainly crossreactive between different variants of GBV-C/HGV
, although proliferative responses appear to be rare. J. Med. Virol. 62:334
-344, 2000. (C) 2000 Wiley-Liss, Inc.