Circulating hepatitis B virus RNA in newborns from carrier mothers

Objective: Despite intermittent flares, progression of chronic infection with hepatitis B virus has generally been related to a decrease in replication levels. In our laboratory, this decrease has been found to be associated with a decline in circulating full-length transcripts (fRNA) and to a shift to truncated transcripts (trRNA). Monitoring fRNA and trRNA as markers allows a more detailed analysis of high or low or non-replicative HBV infection stages. Methods: Here, we determined circulating HBV RNA in newborns from a total of 69 HBsAg-positive carrier mothers with and without immunotherapy administered during the last 3 months of pregnancy. Results: In line with previous observations, serum HBV DNA in newborns was only found when their mothers had not been treated (7/23). HBV RNA measured as trRNA was detected both in the presence and in apparent absence of serum HBV DNA. fRNA ( coexisting with HBV DNA and HBeAg) was detected only in newborns from untreated mothers (8/23) and was always combined with trRNA. In contrast, trRNA was found in newborns from both untreated (20/23) and treated mothers (26/46). Conclusions: Our data strongly suggest a direct intrauterine transmission of a low-replicative (unapparent) HBV infection stage. However, a feto-maternal transfer of trRNA (transfer of a marker) rather than transmission of the infectious virus cannot be excluded.