Production of Antibodies against Hepatitis C Virus Envelope Glycoprotein E2-A Potential Vaccine Against HCV Infection

Currently a number of vaccines are under development against hepatitis C, though an effective hepatitis C vaccine is yet to come. The present study is focused on the development of recombinant vaccine against HCV by utilizing HCV3a envelope glycoprotein E2. HCV3a E2 gene was amplified and cloned first in cloning vector pTG19 and subcloned in expression vector pET21a. E2 protein, expressed in insoluble form, was purified by repeated sonications, followed by denaturation and refolding through fractional dialysis with urea. Multiple alignment with other sequences showed nucleotide variations of HCV3a E2 compared with already reported sequences. A total of 140 (11%) point mutations were found in Pakistan's gene sequence, out of which general and specific differences were 93 (9%) and 47 (4%), respectively. The general differences usually occur in common population while the specific differences are present only in some cases. The 3D structure of E2 was determined. Protein docking with appropriate ligand revealed that V342 and L349 residues were involved in the ligand binding. Interaction of HCV3a infected human sera with HCV3a E2 purified protein was carried out through Enzyme Linked Immunosorbant Assay (ELISA) using HCV antihuman conjugated protein. It was confirmed that the HCV3a E2 purified protein bound with the human serum almost three times more efficiently than the positive control. For raising antibodies against the antigenic protein HCV3a E2, the purified protein E2 was injected subcutaneously into the rabbit (Oryctolagus cuniculus). The antibodies titer in rabbit after immunization in 100% pure serum sample was 0.736 which was 15 times more than that of pre immune control sera (0.049). It is concluded from the current study that purified HCV3a envelope glycoprotein E2 has significant antigenic activity and can potentially be used as recombinant vaccines against HCV infection.