THU-208
Characterization of a novel chemiluminescent enzyme
immunoassay for the quantitation of antibodies to hepatitis B
core antigen class IgG and correlation with intrahepatic HBV
covalently-closed-circular DNA
Gian Paolo Caviglia1, Francesco Tandoi2, Giulia Troshina1,
Lucio Boglione1, Chiara Rosso1, Elisabetta Bugianesi1, Alessia Ciancio1,
Renato Romagnoli2, Mario Rizzetto1, Giorgio Maria Saracco1,
Antonina Smedile1, Antonella Olivero1. 1University of Turin,
Department of Medical Sciences, Turin, Italy; 2University of Turin,
Department of Surgical Sciences, Turin, Italy
Email: [email protected]
Background and aims: Non-invasive biomarkers for the cure and the
management of chronic hepatitis B (CHB) infection are an unmet
need. Our aim was to characterize a novel HBV assay for the
quantitation of anti-HBc IgG and to assess the correlation betweenserum anti-HBc IgG and intrahepatic HBV cccDNA, in comparison to
quantitative hepatitis B surface antigen (qHBsAg) and hepatitis B
core-related antigen (HBcrAg) in patients with CHB infection.
Method: Serum samples and liver specimens were collected from 35
CHB patients (26M/9F; median age 52 [20-70] years; 25 chronic
hepatitis and 10 cirrhosis). Intrahepatic HBV cccDNA was measured
by digital-droplet PCR (Bio-Rad, USA) following total DNA digestion
with plasmid safe ATP-dependent DNase. Serum qHBsAg and HBcrAg
were measured by CLEIA on Lumipulse® G600 II analyzer (Fujirebio,
Japan). qHBsAg limit of sensitivitywas 0.005 IU/ml. The lower limit of
detection (LLoD) and the measurement range of HBcrAg were 2 Log
U/ml and 3-7 Log U/ml, respectively. The WHO 1st International
Standard for anti-HBc (NIBSC code 95/522) was used for the
calibration of anti-HBc IgG assay (Lumipulse® G HBcAb-N, Fujirebio).
Results: The newassay for anti-HBc IgG quantitation showed a linear
dynamic range (R2 = 0.997, p < 0.001); lower limit of detection (LLoD)
and quantitation (LLoQ) were estimated at 0.5 IU/ml and 0.8 IU/ml,
respectively. The coefficient of variation (CV) for repeatability was
3.1% whereas the CV for reproducibility was 4.0%. In liver specimens,
mean HBV cccDNA levels were 3.11 ± 1.14 Log copies/105 cells; in
serum samples, mean qHBsAg, HBcrAg and anti-HBc IgG values were
3.13 ± 1.31 Log IU/ml, 3.8 ± 1.9 Log U/ml and 3.68 ± 0.83 Log IU/ml,
respectively. In 18/35 (51%) patients, HBcrAg was below the
measurement limit of the assay (<3 Log U/ml). HBV cccDNA
correlated significantly with qHBsAg (r = 0.624, p < 0.001), HBcrAg
(r = 0.734, p < 0.001) and anti-HBc IgG (r = 0.553, p < 0.001). In
patients with HBcrAg values <3.0 Log U/ml, intrahepatic HBV cccDNA
correlated significantly with anti-HBc IgG (r = 0.752, p < 0.001) but
not with qHBsAg (r = 0.384, p = 0.116).
Conclusion: Anti-HBc IgG quantitation by CLEIA was a sensitive
and accurate assay. Among the investigated biomarkers, HBcrAg
was confirmed as reliable surrogate marker of intrahepatic HBV
cccDNA. In patients with low HBcrAg levels (<3.0 log), anti-HBc IgG
quantitation by CLEIA may be proposed as alternative marker for
intrahepatic HBV cccDNA measurement. 作者: StephenW 时间: 2019-4-2 13:00