title: Pre-existing immunity against vaccine vectors--friend or foe?
abstract: Over the last century, the successful attenuation of multiple bacterial and viral pathogens has led to an effective, robust and safe form of vaccination. Recently, these vaccines have been evaluated as delivery vectors for heterologous antigens, as a means of simultaneous vaccination against two pathogens. The general consensus from published studies is that these vaccine vectors have the potential to be both safe and efficacious. However, some of the commonly employed vectors, for example Salmonella and adenovirus, often have pre-existing immune responses in the host and this has the potential to modify the subsequent immune response to a vectored antigen. This review examines the literature on this topic, and concludes that for bacterial vectors there can in fact, in some cases, be an enhancement in immunogenicity, typically humoral, while for viral vectors pre-existing immunity is a hindrance for subsequent induction of cell-mediated responses.
authors.affiliation: Ludwig Institute for Cancer Research, Heidelberg, Victoria, Australia.
authors.forename: Manvendra
authors.initials: M
authors.lastname: Saxena
authors.affiliation: School of Applied Sciences, RMIT University, Bundoora, Victoria, Australia.
authors.forename: Thi Thu Hao
authors.initials: TTH
authors.lastname: Van
authors.affiliation: Comparative Genomics Centre, School of Pharmacy and Molecular Sciences, James Cook University, Townsville, Queensland, Australia.
authors.forename: Fiona J
authors.initials: FJ
authors.lastname: Baird
authors.affiliation: School of Applied Sciences, RMIT University, Bundoora, Victoria, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Coloe
authors.affiliation: School of Applied Sciences, RMIT University, Bundoora, Victoria, Australia.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Smooker
mesh_terms: D000818:Animals; D001428:Bacterial Vaccines / Q000235:genetics / Q000276:immunology*; D004337:Drug Carriers; D005822:Genetic Vectors / Q000276:immunology*; D006801:Humans; D014765:Viral Vaccines / Q000235:genetics / Q000276:immunology*
chemical_list: D001428:Bacterial Vaccines; D004337:Drug Carriers; D014765:Viral Vaccines