title: Augmented replicative capacity of the boosting antigen improves the protective efficacy of heterologous prime-boost vaccine regimens.
abstract: Prime-boost immunization regimens have proven efficacious at generating robust immune responses. However, whether the level of replication of the boosting antigen impacts the magnitude and protective efficacy of vaccine-elicited immune responses remains unclear. To evaluate this, we primed mice with replication-defective adenovirus vectors expressing the lymphocytic choriomeningitis virus (LCMV) glycoprotein (GP), followed by boosting with either LCMV Armstrong, which is rapidly controlled, or LCMV CL-13, which leads to a more prolonged exposure to the boosting antigen. Although priming of naive mice with LCMV CL-13 normally results in T cell exhaustion and establishment of chronic infection, boosting with CL-13 resulted in potent recall CD8 T cell responses that were greater than those following boosting with LCMV Armstrong. Furthermore, following the CL-13 boost, a greater number of anamnestic CD8 T cells localized to the lymph nodes, exhibited granzyme B expression, and conferred improved protection against Listeria and vaccinia virus challenges compared with the Armstrong boost. Overall, our findings suggest that the replicative capacity of the boosting antigen influences the protective efficacy afforded by prime-boost vaccine regimens. These findings are relevant for optimizing vaccine candidates and suggest a benefit of robustly replicating vaccine vectors.
  
  
  OBJECTIVE
  The development of optimal prime-boost vaccine regimens is a high priority for the vaccine development field. In this study, we compared two boosting antigens with different replicative capacities. Boosting with a more highly replicative vector resulted in augmented immune responses and improved protective efficacy.
authors.affiliation: Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: Pablo
authors.initials: P
authors.lastname: Penaloza-MacMaster
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Teigler
authors.forename: Rebecca C
authors.initials: RC
authors.lastname: Obeng
authors.forename: Zi H
authors.initials: ZH
authors.lastname: Kang
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Provine
authors.forename: Lily
authors.initials: L
authors.lastname: Parenteau
authors.forename: Stephen
authors.initials: S
authors.lastname: Blackmore
authors.forename: Joshua
authors.initials: J
authors.lastname: Ra
authors.forename: Erica N
authors.initials: EN
authors.lastname: Borducchi
authors.forename: Dan H
authors.initials: DH
authors.lastname: Barouch
mesh_terms: D000256:Adenoviridae; D000818:Animals; D015478:Antigens, Heterophile / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D005822:Genetic Vectors; D006023:Glycoproteins / Q000378:metabolism; D064789:Immunity, Heterologous / Q000276:immunology*; D007117:Immunization, Secondary / Q000379:methods*; D053208:Kaplan-Meier Estimate; D008087:Listeria / Q000276:immunology; D008217:Lymphocytic choriomeningitis virus / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018709:Statistics, Nonparametric; D014616:Vaccinia virus / Q000276:immunology; D014765:Viral Vaccines / Q000276:immunology*; D014779:Virus Replication / Q000502:physiology*
chemical_list: D015478:Antigens, Heterophile; D006023:Glycoproteins; D014765:Viral Vaccines