Significance of hepatitis B virus DNA quantity in transmission between mothers and infants

Objective In order to investigate the influence of serum HBV-DNA quantity in pregnant women on HBV transmission between mothers and infants. Methods Serum HBV-DNA quantity was performed by fluorescence quantitative PCR in 69 paired mothers and infants. Different groups were divided according to the concentration of serum HBV-DNA. Results The average maternal serum HBV-DNA was(6.3±1.9) copies/ml, while the average infant serum HBV-DNA was (4.8±2.0) copies/ml. There was a positive correlation of serum HBV-DNA between paired mothers and infants (r=0.310, P<0.01). Of 69 infants, 45 were positive in HBV-DNA qualitative PCR test and (or) abnormal in HBV serological tests. The mother-infant transmission rate of HBV was 65%. The transmission rate increased when the serum HBV-DNA concentration increased in pregnant women. The cumulative calculation of different groups of maternal serum HBV-DNA showed that the mother-infant transmission rates were significantly different at the levels of 5.0, 6.0 and 7.0 copies/ml. The differences were 32%, 34% and 28%, respectively. In this study, 19 pregnant women were HBeAg positive, 17 were HBsAb positive. The HBV-DNA [(7.6±1.3) copies/ml] and mother-infant transmission rate (90%) in HBeAg positive group were significantly higher than those in HBeAg negative group [(5.8±1.9) copies/ml and 56.0% respectively]. HBV-DNA concentration [(5.3±1.6) copies/ml] and transmission rate (29%) in HBsAb positive group were significantly lower than those in HBsAb negative group [(6.6±1.9) copies/ml, and 76.9%]. Meanwhile HBeAg positive cases were mainly among those pregnant women with higher maternal serum HBV-DNA concentration, and HBsAb positive cases were mainly among the pregnant women with lower maternal serum HBV-DNA concentration. Conclusion HBV transmission rate was influenced by maternal serum HBV-DNA concentration. It seems that the maternal serum critical HBV-DNA levels may influence the mother-infant HBV transmission rate. Key words: Hepatitis B virus; DNA viruses; Disease transmission, vertical; Quantitative detection; Serum concentration interface