[Real-time polymerase chain reaction assay for hepatitis B virus DNA quantification].

INTRODUCTION viral DNA levels in serum samples are a useful marker to monitor the disease progression and the treatment response in patients with chronic hepatitis B. Commercial kits for this purpose are available, but they are considerably expensive. OBJECTIVES to evaluate the analytical performance of a real-time polymerase chain reaction (RT-PCR) assay for Hepatitis B virus DNA quantification. METHODS specific primers to the gene C and TaqMan chemistry in a LightCycler 1.5 equipment was used. A standard curve was made and evaluated. Two hundred and seventy-two serum samples were used to assess the clinical and analytical specificity, the genotypic accuracy and specificity, the intra-assay and interassay coefficients of variation and the comparison with a commercial assay and with the qualitative PCR. RESULTS the standard curve showed a strong linear correlation (r= -1) and low error values in the tested target DNA concentration. Analytical and clinical specificities were 100 %. Genotype accuracy and specificity showed that the differences between the results obtained by RT-PCR assay and those of the reference assay were less than 0.5 Log10. The 95% HBV DNA detection end-point assessed by Probit analysis was 16.41 IU/microL with a dynamic range of quantification of 10(8) IU/mL. Intra-assay and interassay coefficients of variation ranged from 0.16 to 1.45 % and 0.9 to 2.62 % respectively. The RT-PCR assay correlated well with those from a commercial assay (r= 0.964 and r2= 0.929) and with the HBV qualitative PCR, thus confirming its better sensitivity and advantages. CONCLUSIONS the RT-PCR assay is well suited to monitoring HBV DNA levels showing to be sensitive, specific and reproducible. Its application in the clinical practice ensures a better diagnosis and management of patients with chronic hepatitis B in Cuba.