Induction of cytotoxic T-cell response against hepatitis C virus structural antigens using a defective recombinant adenovirus

✍ Scribed by O Bruña-Romero; J J Lasarte; G Wilkinson; K Grace; B Clarke; F Borrás-Cuesta; J Prieto

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 390 KB
• Volume: 25
• Category: Article
• ISSN: 0270-9139
• DOI: 10.1002/hep.510250236

✦ Synopsis

the development of new therapeutic methods are important A replication-defective recombinant adenovirus (RAd), goals for the future. RAdCMV-CE1, containing core and E1 genes of hepatitis Cytotoxic T lymphocytes (CTL) have been shown to play a C virus (HCV) was constructed. RAdCMV-CE1 was able major role in the control of many viral diseases. [8][9][10][11][12][13][14][15] HCV infecto express core and E1 proteins both in mice and human tion has a strong tendency to chronicity suggesting that the cells. Immunization of BALB/c mice with RAdCMV-CE1

CTL reaction against HCV antigens is poor or ineffective. induced a specific cytotoxic T-cell response against the Thus, the characterization of CTL epitopes from HCV protwo HCV proteins. This response was characterized usteins as well as the development of efficient ways of inducing ing a panel of 60 synthetic 14-or 15-mer overlapping pep-CTL in vivo are important steps toward prevention and/or tides (10 amino-acid overlap) spanning the entire setreatment of HCV infection. quence of these proteins. Five main epitopes were found

To induce in vivo CTL against viral antigens, the use of in the core protein, four of which had been previously recombinant viral vectors constitutes an attractive strategy. described either in mice or humans. One single novel

These vectors express recombinant proteins inside the cell, epitope was found in E1. Fine mapping of this E1 deterallowing endogenously synthesized antigens to be processed minant, showed that octamer GHRMAWDM is the miniin a nonendosomal compartment and the derived peptides of mal epitope recognized by cytotoxic T lymphocytes 8-10 residues to be transported to the lumen of endoplasmic (CTL). The cytotoxic T-cell response was H-2 d restricted, reticulum where they bind to class-I major histocompatibility lasted for at least 100 days, and was mediated by T cells complex molecules for presentation to CD8 / CTL at the cell with the classic CD4 0 CD8 / phenotype. This work demonmembrane. In fact, previous studies have shown that the strates that replication-defective recombinant adenoviexpression of HCV antigens, using recombinant vaccinia ruses can efficiently express HCV proteins and are able virus, is an efficient means to induce specific CTL in to induce an in vivo cytotoxic T-cell response against a mice. 16-18 While replication-competent vaccinia recombinants diversity of epitopes from HCV antigens. These vectors entail substantial risks in men, 19 replication-deficient adenoshould be taken into consideration in the design of vacviruses do not appear to be hazardous for humans. 20 These cines and also as a means to stimulate specific T-cell rerecombinant viruses are able to express foreign antigens very sponses in chronic HCV carriers. (HEPATOLOGY 1997;25: efficiently inside nonpermissive cells without spreading the 470-477.) infection. 21, Based on these principles, we constructed a recombinant adenovirus containing core and E1 genes of HCV; we then studied its ability to express these proteins in mice Hepatitis C virus (HCV) is one of the major agents of chronic hepatitis and liver diseases worldwide. 1 Infection and human cells and to induce a cytotoxic immune response in mice. As discussed in later paragraphs, our adenovirus with HCV leads to chronic hepatitis in about 80% of cases. [2][4][5] Chronic hepatitis C frequently evolves to cirrhosis, and a was very effective both in expressing HCV transgenes and in stimulating specific CTL in mice against HCV antigens. significant proportion of patients with liver cirrhosis will develop hepatocellular carcinoma (HCC). 6 Treatment of chronic Fine mapping of CTL epitopes using overlapping peptides allowed us to identify 6 peptides from core and one from E1 hepatitis C with interferon alfa is effective in less than 50% of patients, and a high proportion of those who respond to containing cytotoxic T cell determinants. the treatment relapse soon after interferon withdrawal. 7 It

Methods

is clear that the elaboration of a vaccine against HCV and Mice. Female BALB/c mice (range, 4-6 weeks old) were purchased from IFFA Credo (Barcelona, Spain). They were hosted in appropriated animal care facilities during the experimental period and Abbreviations: RAd, recombinant adenovirus; HCV, hepatitis C virus; CTL, cytotoxic T were handled following the international guidelines required for exlymphocyte. perimentation with animals.