Antigenic relevance of F protein in chronic hepatitis C virus infection.
The hepatitis C virus (HCV) F protein is a recently described, frameshift product of HCV core encoding sequence of genotype 1a. Its function and antigenic properties are unknown. Using enzyme-linked immunosorbent assay, we assessed the prevalence of anti-F antibodies in 154 patients chronically infected with HCV, 65 patients with other liver diseases, and 121 healthy controls. For this purpose, we expressed a highly purified HCV F recombinant protein from HCV genotype 1a in Escherichia coli. Because the F protein shares the 10 first amino acids with the core protein, the anti-HCV F response was also assessed by a F recombinant protein deleted of its 10 first amino acids [Delta(1-10)-F]. Ninety-six (62%) of the 154 HCV serum samples reacted with the complete F recombinant protein, whereas 39 (25%) showed a weaker anti-Delta(1-10)F reactivity and 150 (97%) had anti-core antibodies. No reactivity against F, Delta(1-10)F, or core was detected in any of the controls. To exclude a potential cross-reaction of anti-F antibodies with anti-core antibodies, a specific enzyme-linked immunosorbent assay was performed for anti-core antibodies. The specificity of anti-F antibodies was confirmed using an F synthetic peptide. The prevalence of anti-F antibodies did not correlate with HCV RNA serum level, genotype, or stage of liver disease. Sequence analysis from 8 anti-F-positive and 5 anti-F-negative serum samples did not reveal any particular difference potentially accounting for their respective anti-F responses. In conclusion, the F protein elicits specific antibodies in 62% of individuals chronically infected with HCV; such anti-F response does not seem to be affected by the F sequence heterogeneity.
Komurian-Pradel
Florence
F
UMR2142 CNRS-bioMérieux, IFR 128 BioSciences Lyon-Gerland, Lyon, France.
Rajoharison
Alain
A
Berland
Jean-Luc
JL
Khouri
Valérie
V
Perret
Magali
M
Van Roosmalen
Mark
M
Pol
Stanislas
S
Negro
Francesco
F
Paranhos-Baccalà
Glaucia
G
D000328:Adult; D000368:Aged; D000939:Epitopes; D005260:Female; D016368:Frameshift Mutation; D005838:Genotype; D016174:Hepacivirus / Q000235:genetics* / Q000276:immunology; D018937:Hepatitis C Antibodies / Q000097:blood; D019698:Hepatitis C, Chronic / Q000453:epidemiology / Q000276:immunology* / Q000821:virology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D016036:Seroepidemiologic Studies; D014758:Viral Core Proteins / Q000235:genetics* / Q000276:immunology*
D000939:Epitopes; D018937:Hepatitis C Antibodies; D011994:Recombinant Proteins; D014758:Viral Core Proteins; C433031:hepatitis C protein F, Hepatitis C virus