An assay to measure avidity index (AI) was developed to diagnose incident hepatitis C virus (HCV) infections. The assay demonstrated an AI value statistically significantly lower in primary HCV infections than in chronic infections. When the assay was applied to past resolved infections, the difference in AI values was not as significant as the difference between incident and chronic infections. Lower AI values obtained in past resolved infections may be directly related to lower levels of immunoglobulin G anti-HCV in past resolved infections than in either new infections or chronic infections.
The new HEV EIA developed in the present study is a highly specific diagnostic assay for the detection of anti-HEV activity in serum specimens obtained from different epidemiologic settings.
In spite of extensive research, no effective vaccine against hepatitis C virus (HCV) has been devel oped so far. DNA immunization is a potent technique of vaccine design strongly promoting the cellular arm of immune response. The genes encoding nonstructural HCV proteins (NS2-NS5B) are promising candi dates for vaccine development. NS5A is a protein involved in viral pathogenesis, in the induction of immune response, and probably in viral resistance to interferon treatment. The objective of this study was to construct a DNA vaccine encoding NS5A protein and evaluate its immunogenicity. A plasmid encoding a full size NS5A protein was produced using the pcDNA3.1 (+) vector for eukaryotic expression system. The expression of the NS5A gene was confirmed by immunoperoxidase staining of the transfected eukaryotic cells with anti NS5A monoclonal antibodies. Triple immunization of mice with the plasmid vaccine induced a pronounced cellular immune response against a broad spectrum of NS5A epitopes as assessed by T cell proliferation and secretion of antiviral cytokines IFN γ and IL 2. In T cell stimulation in vitro experiments, NS5A derived antigens were modeled by synthetic peptides, recombinant proteins of various genotypes, and phages carrying exposed NS5A peptides. A novel immunomodulator Immunomax showed high adjuvant activity in DNA immunization. The data obtained indicate that the suggested DNA construct has a strong potential in the development of the gene vaccines against hepatitis C.
An artificial antigen composed of 12 small antigenic regions derived from the ORF2 and ORF3 HEV proteins was designed. The gene encoding for this artificial antigen was assembled from synthetic oligonucleotides by a new method called Restriction Enzyme-Assisted Ligation (REAL). The diagnostic relevance of this second generation HEV mosaic protein (HEV MA-II) was demonstrated by testing this antigen against a panel of 142 well defined anti-HEV positive and anti-HEV negative serum samples. The data obtained in this study support the substantial diagnostic potential of this HEV mosaic antigen.
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