Unlike attenuated or killed vaccines, subunit vaccines are often more effective vaccine alternatives that can be produced at lower cost. These subunits are comprised of single or multi-epitope peptides that can increase immunity against the specific virus following vaccination. A complication to this approach is that these peptide sequences need to first be identified, which can be challenging with viruses that undergo antigenic changes as a result of antigenic shift or drift, such as the influenza virus or HIV.
To simplify the vaccine design process, epitope discovery is utilized to span the entire sequences of known viral protein antigens. These peptide sequences are used to predict the B- and T-cell epitopes to stimulate passive immunity. Examples of studies that have used peptide libraries for vaccine development against viral diseases are:
Severe Acute Respiratory Syndrome (SARS): peptide libraries were used to screen for B-cell epitopes that recognize the SARS virus for developing a diagnostic tool
Herpes simplex virus: libraries containing sequences of a specific glycoprotein on Herpes simplex was screened with monoclonal antibodies to find the peptide with the highest binding affinity
Japanese encephalitis virus (JEV): the envelope protein of JEV was screened to identify functional epitopes that can be targeted with neutralizing antibodies