Neonatal Exposure to Hepatitis C Virus Antigens in Uninfected Children Born to Infected Mothers

Afrodite Psaros Einberg, Erwin Daniel Brenndörfer, Lars Frelin, Lena Hallberg, Matti Sällberg, Björn Fischler

Vertical transmission of hepatitis C virus (HCV) infection is uncommon and occurs in around 5% of births from HCV infected mothers. The reason for the low transmission rate is unclear. We aimed to investigate if there is evidence of HCV exposure also in the non-infected children born to HCV infected mothers by the presence of a detectable immune response. Serum and peripheral blood mononuclear cells from 9 HCV vertically infected children, 32 uninfected children born to HCV infected mothers, and 15 HCV chronically infected mothers, were analyzed. HCV-RNA negative adults and children were used as controls. HCV specific T cell responses were analyzed by interferon gamma (IFN-γ) using an enzyme-linked immunospot (ELISpot) assay and 3H-thymidine incorporation assay. HCV antibodies were also analyzed. An HCV specific T cell response was detected in 73% (11/15) of the HCV infected mothers, 67% (6/9) of the vertically infected children, 56% (18/32) of the exposed but uninfected children and in 10% and 20% of the control groups, respectively. The two groups of HCV exposed children both had a significantly higher proportion of HCV specific T cell responders compared to pediatric controls (p = 0.01 and p = 0.02). HCV specific immune responses were more common in children born to HCV infected mothers, regardless of the presence of HCV RNA. We conclude that non-infected children born to HCV infected mothers may have been exposed to HCV antigens.