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

Abstract

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.