Use of Phage Displayed Peptides Libraries for Epitope Mapping of Bovine Viral Diarrhea Virus E2 Protein

In this study, it was attempted to map immunogenic epitopes contained within the E2 glycoprotein of Bovine Viral Diarrhea Virus (BVDV) using a random phage display peptide library and serum against a recombinant BVDV carrying the glycoprotein E2 of a close relative virus, Border disease was used. This approach was hypothesized to favor the later selection of BVDV E2 specific mimotopes after positive pannings with serum from a bovine infected with wild type BVDV. Phage clones obtained after three rounds of selection were sequenced and analyzed by informatics tools. Four sequences were chosen to synthesize peptides with different modifications to be utilized in a peptide ELISA test and as immunogens in guinea pigs and bovines. Moreover, groups of mice were immunized directly with phages displaying the selected four mimotopes. Mice and guinea pigs produced antibodies against the immunogenic peptides as seen by the ELISA test, but these antibodies failed to neutralize the virus. However, serum with high neutralizing titer from an infected calf recognized some of the selected peptides in an ELISA test. Present results suggest that the use of a recombinant virus does not help in the selection of mimotopes from a random phage display peptide library and that all selected sequences need to be tested for their immunogenic potential.