Development of a Recombinant Based ELISA using Specific Antibodies to F Protein in HCV Chronically Infected Patients-A Seroprevalence Study

Antibody Development to HCV Alternate Reading Frame Protein in Liver Transplant Candidate and its Computational Analysis

Background::

HCV Alternate Reading Frame Protein (ARFP) is a frameshift product of HCV-core encoding. Here, we characterized specific anti-ARFP antibodies in Liver Transplant Candidate (LTC) and chronic HCV-infected patients.

Methods::

The ARFP gene was cloned and the recombinant protein was purified using Nickel chromatography and confirmed by western blotting. ELISA was developed using recombinant core-1a, core- 1b, ARFP-1a protein, and 99-residue synthetic ARFP 1b peptide. By several Bioinformatics tools, general properties, immunogenic epitopes, and structures of these proteins were obtained.

Results::

The seroprevalence of anti-core and anti-ARFP antibodies was 100% in LTC patients, but only 75.2% and 94.3% of chronic patients had evidence of anti-ARFP and anti-core antibodies, respectively. In-silico results demonstrated physicochemical features, antigen properties and potential interactors that could describe progression toward advanced liver disease.

Conclusion::

As the first report, the prevalence of anti-ARFP antibodies in LTC patients is of the order of 100% and titer of anti-ARFP antibody was significantly higher in LTC patients compared to chronic individuals, suggesting the possible role of ARFP in the progression toward advanced liver disease. In addition, docking analysis determined several interactor proteins such as prefoldin 2, cathepsin B, vitronectin, and angiotensinogen that have an important role in progression to chronic infection and liver disease development.

F protein increases CD4+CD25+ T cell population in patients with chronic hepatitis C

HCV is a global health problem with an estimated 230 million chronically infected people worldwide. It has been reported that a 17-kd protein translated from core-encoding genomic region can contribute to immune-mediated mechanisms associated with the development of the chronic disease. Also, Treg cells can be contributed to an inadequate response against the viruses, leading to chronic infection. Here we evaluated the ability of protein F to modulate the frequency of CD4+CD25+FoxP3+T and IL-10+T cells in patients with chronic HCV infection. F gene was amplified and cloned in the expression vector. The protein was purified and used for stimulation of PBMCs in the HCV chronic patients and the control groups. The frequency of CD4+CD25+FoxP3+ T cell-like populations and IL-10-producing CD4+CD25+ T cells was assessed in the HCV-infected patients and in the healthy controls by flow cytometry, which showed an increase of both CD4+CD25+FoxP3+ T cell-like population and IL-10-producing CD4+CD25+ T cells in the HCV-infected patients positive for anti-F antibody. Our results suggest the potential involvement of F and core antigens in increasing the frequency of CD4+CD25+FoxP3+ T cell-like population and IL-10-producing CD4+CD25+ T cells which may be associated with HCV-persistent infection.