A new HCV core antigen assay based on disassociation of immune complexes: an alternative to molecular biology in the diagnosis of early HCV infection.
BACKGROUND
An EIA based on immune complex disassociation of nucleocapsid proteins of HCV has been developed to detect and quantify HCV core antigen.


METHODS
To evaluate whether this new assay (trak-C, Ortho Clinical Diagnostics) could be an alternative to NAT during the window period, its sensitivity in this context was assessed, and its performance was compared with that of a first-generation HCV core antigen assay dedicated to the blood screening (HCV core antigen ELISA). Studied populations included nine HCV RNA-positive, HCV antibody-negative blood donors and 23 hemodialysis patients who underwent an HCV seroconversion. From these individuals, 81 samples (23 HCV RNA-negative and 58 HCV RNA-positive) sequentially collected during the phase before seroconversion were tested.


RESULTS
The nine blood donor samples were positive for the presence of HCV core antigen by the trak-C, and 6 of 8 tested were positive for the presence of HCV core antigen by blood screening ELISA. In the hemodialysis cohort, the 23 HCV RNA-negative samples were negative with the two HCV core antigen assays. Among the 58 HCV RNA-positive samples, 46 of 57 (80.7%) tested were positive for the presence of HCV core antigen with the blood screening assay, and 57 of 58 (98.2%) were positive for the presence of HCV core antigen with the trak-C. The mean delays in detecting HCV infection between trak-C and the appearance of HCV antibodies, between HCV RNA testing and trak-C, and between trak-C and HCV core antigen ELISA were 58.2, 0.24, and 3.33 days, respectively.


CONCLUSIONS
Trak-C was more sensitive than the blood screening assay and had similar performance to HCV RNA assay in the window period. Trak-C could constitute an alternative to NAT for the diagnosis of HCV infection during the window period, especially when molecular biology procedures cannot be implemented.
Laperche
Syria
S
Department of Blood Transmissible Agents, National Institute of Blood Transfusion, Paris, France. slaperche@ints.fr
Le Marrec
Nadine
N
Simon
Nicole
N
Bouchardeau
Françoise
F
Defer
Christine
C
Maniez-Montreuil
Michèle
M
Levayer
Thierry
T
Zappitelli
Jean-Pierre
JP
Lefrère
Jean-Jacques
JJ
D000936:Antigen-Antibody Complex; D001782:Blood Donors; D004797:Enzyme-Linked Immunosorbent Assay; D016174:Hepacivirus / Q000235:genetics; D006526:Hepatitis C / Q000175:diagnosis*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D012367:RNA, Viral / Q000097:blood; D006435:Renal Dialysis; D012680:Sensitivity and Specificity; D014758:Viral Core Proteins / Q000097:blood*
D000936:Antigen-Antibody Complex; D012367:RNA, Viral; D014758:Viral Core Proteins; C069130:nucleocapsid protein, Hepatitis C virus