Peptide vaccination is superior to genetic vaccination using a recombineered bacteriophage λ subunit vaccine

Genetic immunization holds promise as a vaccination method, but has so far proven ineffective in large primate and human trials. Herein, we examined the relative merits of genetic immunization and peptide immunization using bacteriophage X. Bacteriophage X has proven effective in immune challenge models using both immunization methods, but there has never been a direct comparison of efficacy and of the quality of immune response. In the current study, this vector was produced using a combination of cis and trans phage display. When antibody titers were measured from immunized animals together with IL-2, IL-4 and IFN gamma production from splenocytes in vitro, we found that proteins displayed on X were superior at eliciting an immune response in comparison to genetic immunization with X. We also found that the antibodies produced in response to immunization with X displayed proteins bound more epitopes than those produced in response to genetic immunization. Finally, the general immune response to X inoculation, whether peptide or genetic, was dominated by a Th1 response, as determined by IFN gamma and IL-4 concentration, or by a higher concentration of IgG2a antibodies. (C) 2011 Elsevier Ltd. All rights reserved.