Heterologous prime-boost regimens using rAd35 and rMVA vectors elicit stronger cellular immune responses to HIV proteins than homologous regimens

PLoS One. 2012;7(9):e45840. doi: 10.1371/journal.pone.0045840. Epub 2012 Sep 26.

Abstract

We characterized prime-boost vaccine regimens using heterologous and homologous vector and gene inserts. Heterologous regimens offer a promising approach that focuses the cell-mediated immune response on the insert and away from vector-dominated responses. Ad35-GRIN/ENV (Ad35-GE) vaccine is comprised of two vectors containing sequences from HIV-1 subtype A gag, rt, int, nef (Ad35-GRIN) and env (Ad35-ENV). MVA-CMDR (MVA-C), MVA-KEA (MVA-K) and MVA-TZC (MVA-T) vaccines contain gag, env and pol genes from HIV-1 subtypes CRF01_AE, A and C, respectively. Balb/c mice were immunized with different heterologous and homologous vector and insert prime-boost combinations. HIV and vector-specific immune responses were quantified post-boost vaccination. Gag-specific IFN-γ ELISPOT, intracellular cytokine staining (ICS) (CD107a, IFN-γ, TNF-α and IL-2), pentamer staining and T-cell phenotyping were used to differentiate responses to inserts and vectors. Ad35-GE prime followed by boost with any of the recombinant MVA constructs (rMVA) induced CD8+ Gag-specific responses superior to Ad35-GE-Ad35-GE or rMVA-rMVA prime-boost combinations. Notably, there was a shift toward insert-focus responses using heterologous vector prime-boost regimens. Gag-specific central and effector memory T cells were generated more rapidly and in greater numbers in the heterologous compared to the homologous prime-boost regimens. These results suggest that heterologous prime-boost vaccination regimens enhance immunity by increasing the magnitude, onset and multifunctionality of the insert-specific cell-mediated immune response compared to homologous vaccination regimens. This study supports the rationale for testing heterologous prime-boost regimens in humans.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenoviridae / genetics
  • Animals
  • CD8-Positive T-Lymphocytes / cytology
  • Cytokines / metabolism
  • Enzyme-Linked Immunosorbent Assay / methods
  • Female
  • Flow Cytometry / methods
  • HIV / metabolism*
  • Histocompatibility Antigens Class I / metabolism
  • Humans
  • Immune System / physiology*
  • Immunity, Cellular
  • Immunologic Memory
  • Interferon-gamma / metabolism
  • Lysosomal-Associated Membrane Protein 1 / biosynthesis
  • Mice
  • Mice, Inbred BALB C
  • Spleen / cytology
  • Spleen / metabolism
  • T-Lymphocytes / cytology
  • Viral Proteins / metabolism*

Substances

  • Cytokines
  • Histocompatibility Antigens Class I
  • Lysosomal-Associated Membrane Protein 1
  • Viral Proteins
  • Interferon-gamma