Induction of hepatitis C virus (HCV)-specific T cells by needle stick injury in the absence of HCV-viraemia

Background The risk of hepatitis C virus (HCV) infection after occupational exposure is low with seroconversion rates between 0 and 5%. However, factors associated with natural resistance against HCV after needle stick injury are poorly defined. HCV‐specific T‐cell responses have been described in cross‐sectional studies of exposed HCV‐seronegative individuals. Materials and methods In this study, we prospectively followed 10 healthcare professionals who experienced an injury with an HCV‐contaminated needle. Blood samples were taken on the day or the day after the event and at different time points during follow‐up for up to 32 months. HCV‐specific T‐cell responses were investigated directly ex vivo and in T‐cell lines. Results None of the individuals became positive for HCV‐RNA in serum tested with the highly sensitive transcription‐mediated amplification (TMA)‐assay or in peripheral blood mononuclear cells (PBMC). All of them remained anti‐HCV negative throughout follow‐up. At the time of injury, HCV‐specific CD4+ T‐cell responses were already detectable in two individuals and became detectable thereafter in three additional persons. Transient HCV‐specific CD8+ T‐cell responses developed in two HLA‐A2 positive patients, which became negative until the most recent follow‐up after 5 and 17 months, respectively. Conclusion We demonstrate the development of HCV‐specific T cells in HCV‐exposed individuals after needle stick injury indicating subinfectious exposure to HCV. T‐cell immunity against HCV may contribute to the low prevalence of HCV in medical healthcare professionals in Western countries.