The influence of T cell cross-reactivity on HCV-peptide specific human T cell response

Detection of hepatitis C virus (HCV)-specific T cell response after exposure to hepatitis C in anti-HCV-positive or anti-HCV-negative patients has been associated with an ability to successfully control the infection. However, cross-reactivity between common human pathogens and HCV sequences has been demonstrated. The aim of this study was to investigate the impact of T cell cross-reactivity on HCV-specific T cell responses and their detection in HCV infected and non-infected subjects. The magnitude, function, and cross-reactivity of HCV peptide reactive T cells were studied in non-HCV-infected newborns and adults using a broad array of HCV peptides (601 peptides) spanning the entire HCV sequence. Comparisons were made with responses present in recovered and in chronically HCV-infected patients. HCV peptide reactive T cells are detectable in adults irrespective of previous HCV exposure and cross-reactivity between HCV peptides, and sequences of common pathogens, such as human herpes virus 1, can be demonstrated. Furthermore, the comprehensive magnitude of HCV-peptide reactive T cells present in chronically HCV-infected patients is similar and in some cases even lower than that of HCV-peptide reactive T cell response found in HCV-negative adults. In conclusion, the presence of oligo-specific HCV-peptide reactive T cells in humans does not always reflect a demonstration of previous HCV contact, whereas cross-reactivity with other common pathogens can potentially influence the HCV-specific T cell profile. The conspicuous deficit of HCV-peptide-specific T cells found in chronically HCV-infected patients confirms the profound collapse of virus-specific T cell response caused by HCV persistence.