International Health and Tropical Medicine Articles

Application of real-time PCR to quantify hepatitis B virus DNA in chronic carriers in The Gambia.

Maimuna E. Mendy et al. — Thu, 15 Dec 2011 04:43:12 PST

BACKGROUND/AIM: The study aimed at developing a real-time quantitative PCR assay to monitor HBV serum virus load of chronic carriers enrolled in therapeutic trials.

METHOD: Quantitative real-time PCR assay was carried out using SYBR-Green signal detection and primers specific to the S gene. Thermal cycling was performed in an ABi 5700 sequence detection system. The assay was calibrated against an international HBV DNA standard and inter- and intra-assay reproducibility determined. Levels of viral load were monitored for 1-year in lamivudine treated carriers. Correlation between HBV DNA levels and HBeAg sero-status was determined in untreated carriers.

RESULTS: The qPCR assay showed good intra- and inter-assay reproducibility over a wide dynamic range (1.5 x 103 to 1.5 x 108 copies/mL) and correlated well with those from a commercial assay (r = 0.91, (p < 0.001). Viral load levels dropped dramatically but temporarily during and after a short course of lamivudine therapy. HBV DNA was a more reliable indicator of the presence of virus than HBe antigen and was detected in 77.0% (161/209) of HBeAg negative and in all HBeAg positive carriers.

CONCLUSION: This method is reliable, accurate, and reproducible. HBV DNA Quantification by qPCR can be used to monitor the efficacy of HBV therapy and useful in understanding the natural history of HBV in an endemic area.

Changes in viral load and HBsAg and HBeAg status with age in HBV chronic carriers in The Gambia.

Maimuna E. Mendy et al. — Mon, 05 Dec 2011 06:35:41 PST

BACKGROUND: Little is known about changes in hepatitis B viral load (HBV DNA) in relation to age in Africa. The aim of this study is to determine the natural course of HBV chronic infection, particularly in relation to sequential changes in serum HBV DNA levels and hepatitis B surface (HBsAg) antigen/hepatitis e antigen (HBeAg) status by age.

METHODS: The study was conducted on 190 HBV chronic carriers, aged 1-19 years who were followed for 19 years. 160, 99 and 123 were traced at 5, 9 and 19 years later. All available samples were tested for HBsAg and HBeAg, whilst 170, 61, 63 and 81 were tested for HBV DNA at the baseline, and at 5, 9 and 19 years following recruitment.

RESULTS: In general HBeAg which correlated with high levels of HBV DNA was lost at a much faster rate than HBsAg. 86% of the carriers who were recruited at the age of 1-4 yrs lost HBeAg by the age of 19 years compared to 30% who lost HBsAg. HBeAg negative carriers had serum HBV DNA levels of < 105 copies per mL, HBV DNA positivity declined from 100% in 1-4 yrs old carriers at recruitment to 62.5%,60% and 88% at 5, 9 and 19 years respectively following recruitment.

CONCLUSION: After 19 years of follow up, the majority of HBV surface antigen carriers had lost HBeAg positivity and had low levels of viral replication. However small proportions (10-20%) retained HBeAg and continue to have high levels of viral replication.