Hepatitis C Virus-specific immune response among needle-stuck Egyptian healthcare workers at high risk of infection without viremia or seroconversion

Abstract Hepatitis C Virus (HCV)-specific cell-mediated immunity (CMI) was reported in exposed individuals e.g. IV drug users without seroconversion or viremia. We investigated the HCV-specific CMI response in seronegative, aviremic healthcare workers (HCWs) at the National Liver Institute who are at high risk of becoming infected with HCV after occupational exposure as more than 70% of their patients are HCV-infected. We quantified the CMI responses in 15 Egyptian HCWs with a recent history of a needle stick injury and who remained seronegative and aviremic for at least four months. We used ex vivo enzyme-linked immunospot (ELISPOT) assay to quantify interferon gamma (IFNγ) production in response to 7 HCV genotype 4 overlapping 15mer peptide pools and phenotyped the responding cells by flow cytometry. A positive HCV-specific IFN-γ responses (>55 spot forming cells (SFCs)/million PBMC) was elicited for 2-6 HCV pools in 8 (53%) of the HCW while 7 (47%) subjects responded to one or none of the pools tested with a total mean of 1069 (SEM ±239) and 118 (±17) IFNγ SFC, respectively. In summary, the majority of HCW demonstrated HCV-specific T cell responses for multiple HCV peptides and remained uninfected despite their high-risk of exposure. These responses suggest that the percentage of subjects clearing the infection is much higher than reported and their potential role in protection from HCV infection is important for understanding HCV pathogenesis and vaccine development.