title: Murine responses to recombinant MVA versus ALVAC vaccines against tumor-associated antigens, gp100 and 5T4.
abstract: Virally vectored cancer vaccines comprise a new form of immunotherapy that aim to generate anti-tumor immune responses with potential for tumor clearance and enhanced patient survival. Here, we compared 2 replication-deficient poxviruses modified vaccinia Ankara (MVA) and ALVAC(2) in their ability to induce antigen expression and immunogenicity of the tumor-associated antigens (TAAs) 5T4 and gp100. To facilitate the comparison, recombinant MVA-gp100M and ALVAC(2)-5T4 were constructed to complement existing ALVAC(2)-gp100M and MVA-5T4 vectors. Recombinant TAA expression in chicken embryo fibroblast cells was confirmed by Western blot analysis. 5T4 expression was approximately equal for both viruses, whereas ALVAC-derived gp100 was quickly degraded, at a time point when MVA-derived gp100 was still stable and expressed at high levels. Human leukocyte antigen-A2 transgenic mice were vaccinated with recombinant viruses and the CD8 T-cell responses elicited against each TAA were monitored by interferon-γ enzyme-linked immunospot. No 5T4 peptide responses were detected using splenocytes from mice vaccinated with either vector, whereas vaccination with MVA elicited a significantly higher gp100-specific response than ALVAC(2) at 10 PFU (P<0.001). In CD-1 mice, each vector elicited similar 5T4 antibody responses, whereas MVA was more potent and induced gp100 antibody responses at a lower immunization dose than ALVAC (P<0.001). In this study, immunogenicity varied depending on the viral vector used and reflected vector-associated differences in in vitro TAA expression and stability. These findings suggest that novel vector-transgene combinations must be assessed individually when designing vaccines, and that stability of vector-encoded proteins produced in vitro may be useful as a predictor for in vitro immunogenicity.
authors.affiliation: Department of Pathobiology, University of Guelph, Guelph, Toronto, ON.
authors.forename: David G
authors.initials: DG
authors.lastname: Hanwell
authors.forename: Bryan
authors.initials: B
authors.lastname: McNeil
authors.forename: Lucian
authors.initials: L
authors.lastname: Visan
authors.forename: Lauren
authors.initials: L
authors.lastname: Rodrigues
authors.forename: Pamela
authors.initials: P
authors.lastname: Dunn
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Shewen
authors.forename: Grace E
authors.initials: GE
authors.lastname: Macallum
authors.forename: Patricia V
authors.initials: PV
authors.lastname: Turner
authors.forename: Thorsten U
authors.initials: TU
authors.lastname: Vogel
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D000951:Antigens, Neoplasm / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D019496:Cancer Vaccines / Q000008:administration & dosage / Q000276:immunology*; D002642:Chick Embryo; D005260:Female; D015870:Gene Expression; D023061:Gene Order; D005822:Genetic Vectors / Q000235:genetics / Q000276:immunology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology*; D051379:Mice; D009369:Neoplasms / Q000276:immunology / Q000628:therapy; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000276:immunology; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology*; D058951:gp100 Melanoma Antigen / Q000235:genetics / Q000276:immunology*
chemical_list: C078788:ALVAC vaccine; D000906:Antibodies; D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; C560489:MVA vaccine; D008562:Membrane Glycoproteins; D019444:Vaccines, DNA; D014765:Viral Vaccines; D058951:gp100 Melanoma Antigen; C063709:trophoblastic glycoprotein 5T4, human