RESUMEN
<p><b>OBJECTIVE</b>To determine the relationship between IgG antibody against the C-terminal region of the preS1 protein of hepatitis B virus and the early response to interferon therapy in chronic hepatitis B.</p><p><b>METHODS</b>69 patients with chronic hepatitis B virus (genotype B) infection were recruited in this study. 42 patients were treated with interferon-a-1b or a-2b, and 27 patients were treated with PEG interferon (a-2a). Peptide mimicking the C-terminal region of the preS1 protein (94-117aa) of genotype B HBV were synthesised, and the IgG antibody against this peptide was measured by ELISA, and the early response to IFN-alpha therapy was judged by the effect on the viral kinetics, transaminase and the status of HBeAg at 12th week after the treatment.</p><p><b>RESULTS</b>21 patients were positive for anti-preS1 antibody, and 48 patients were negative for anti-preS1 antibody. After 12 weeks of the treatment, the average decrease in viral levels was 3.37log10 copies/ml and 0.33log10 copies/ml in anti-PreS1 positive patients and anti-preS1 negative patients, respectively, the difference between the two groups was significant (Z = -3.658, P = 0.000); the average decrease in ALT levels was 92 U/L and 30.5 U/L in these two groups, respectively (Z = -2.132, P = 0.033). The rate of hepatitis B e antigen (HBeAg) loss was 41.2% (7/17) and the rate of anti-HBe seroconversion was 5.9% (1/17) in anti-PreS1 positive group, however, the rate of hepatitis B e antigen loss was only 12.8% (5/39), and none of the patients in anti-PreS1 negative group showed anti-HBe seroconversion, the difference between the two groups was significant (Z = -5.110, P = 0.000). The rates of response were 71.4% (15/21) and 16.7% (8/48), respectively, in anti-PreS1 positive group and anti-PreS1 negative group. The rates of complete response were 23.8% (5/21) and 6.25% (3/48), respectively, in these two groups. The positive predictive value (PPV) of anti-C-terminal region of preS1 (94-117aa) antibody in predicting early response was 71.6% and the negative predictive value (NPV) was 83.3%. CONCLUCIONS: Detection of anti-C-terminal region of preS1 (94-117aa) antibody may help to improve the efficacy of INF-alpha therapy for chronic hepatitis B (CHB).</p>