Deep sequencing of hepatitis B surface antigen gene in the preserved umbilical cords in immunoprophylaxis failure against mother-to-child HBV transmission

Abstract

BackgroundVaccine escape mutants (VEMs) are one of the causes of breakthrough infections in the mother-to-child transmission of hepatitis B virus (HBV). We hypothesized that VEMs existing as minor populations in the maternal blood are associated with breakthrough infections in children. We sought to determine whether VEMs exist as minor populations in the preserved umbilical cords of children with breakthrough infections.Case presentationTwo families (Family 1: three children, Family 2: two children) were enrolled. Despite immunoprophylaxis, a breakthrough infection occurred in two Family 1 children and two Family 2 children. Preserved umbilical cords, serum, and nails were used for the HBV DNA analysis. To detect VEMs, we performed direct and deep sequencing of hepatitis B surface antigen gene. The direct sequencing showed that there were no VEMs in the serum of the children or mother of Family 1 and family 2, but it identified a G145A mutant in the nails of the mother of Family 2. In Family 1, deep sequencing detected a T143S mutant as a minor population (1.7–2.0%) in the umbilical cords and serum of all three children and in the serum of the mother. A T126A mutant was also detected in the umbilical cord (9.2%) and serum (7.0%) of the first-born child of Family 1. In Family 2, the deep sequencing showed no VEMs in the umbilical cords, but it detected D144A (2.5%) and G145A (11.2%) mutants in the serum of the 2nd-born child.ConclusionsVEMs were present as minor populations in the preserved umbilical cords of children with breakthrough infections. The VEMs did not become major populations after the breakthrough infections. The evolution of VEMs from a minor form to a major form might not be a prerequisite for breakthrough infections in mother-to-child transmission.

Signature of chronic hepatitis B virus infection in nails and hair

“…On the basis of the growth rate, nail clippings could retain HBV DNA at least several months after the disappearance of serum HBV DNA. Previously, we reported a mother-to-child transmission case in which a past time frame of nails contributed to the detection of vaccine scape mutant [ 37 ]. In the report, a 2-year-old boy was chronically infected through breakthrough infection and G145R vaccine escape mutant was detected in his serum.…”

Signature of chronic hepatitis B virus infection in nails and hair

“…On the basis of the growth rate, nail clippings could retain HBV DNA at least several months after the disappearance of serum HBV DNA. Previously, we reported a mother-tochild transmission case in which a past time frame of nails contributed to the detection of vaccine scape mutant [39]. In the report, a 2-year-old boy was chronically infected through breakthrough infection and G145R vaccine escape mutant was detected in his serum.…”

Integration of Viral Genome to Human Genomic DNA in Nails of Patients with Chronic Hepatitis B Virus Infection

“…Moreover, the integration of HBV DNA into host genomic DNA is observed in peripheral blood cells (6) , (7) . Recent studies have shown that HBV DNA can be detected in the nails and hair of patients with acute and chronic HBV infection (8) , (9) , (10) . In addition to HBV, cytomegalovirus (CMV) DNA was detected in the nails of a child with congenital CMV infection (11) .…”