Genotype switching in hepatitis B virus as a potential risk for vertical transmission from mother-to-child was first reported

Objective

Hepatitis B virus (HBV) infection represents a significant global public health concern and is endemic in numerous populations. In China, mother-to-child transmission (MTCT) remains the predominant route of HBV infection. The administration of the Hepatitis B vaccine and Hepatitis B immunoglobulin (HBIG) to neonates born to mothers with chronic HBV infection constitutes the primary strategy to mitigate the risk of perinatal transmission. Nevertheless, elevated maternal viral loads are a critical risk factor for vertical transmission of HBV, even when infants are immunized at birth and treated with HBIG.

Methods

In this study, we enrolled 32 mother-child pairs with confirmed vertical transmission of HBV. Despite antiviral therapy administered to three pregnant women, which successfully reduced their viral loads below the threshold (HBV DNA <5.3 log10 IU/mL) within 24 weeks of pregnancy, their infants still contracted HBV despite receiving immunization and HBIG at birth.

Results

Utilizing next-generation sequencing (NGS) and comprehensive HBV genomic analysis, we identified that 28 pairs (87.5 %) were infected with HBV genotype B2, three pairs (9.3 %) with genotype C1, and three pairs (9.3 %) exhibited genotype switching.

Conclusion

This study is the first to report the phenomenon of HBV genotype switching during MTCT, with the underlying mechanisms explored through the analysis of HBV quasispecies haplotypes.