title: Active vaccination with vaccinia virus A33 protects mice against lethal vaccinia and ectromelia viruses but not against cowpoxvirus; elucidation of the specific adaptive immune response.
abstract: Vaccinia virus protein A33 (A33VACV) plays an important role in protection against orthopoxviruses, and hence is included in experimental multi-subunit smallpox vaccines. In this study we show that single-dose vaccination with recombinant Sindbis virus expressing A33VACV, is sufficient to protect mice against lethal challenge with vaccinia virus WR (VACV-WR) and ectromelia virus (ECTV) but not against cowpox virus (CPXV), a closely related orthopoxvirus. Moreover, a subunit vaccine based on the cowpox virus A33 ortholog (A33CPXV) failed to protect against cowpox and only partially protected mice against VACV-WR challenge. We mapped regions of sequence variation between A33VACV and A33CPXVand analyzed the role of such variations in protection. We identified a single protective region located between residues 104-120 that harbors a putative H-2Kd T cell epitope as well as a B cell epitope - a target for the neutralizing antibody MAb-1G10 that blocks spreading of extracellular virions. Both epitopes in A33CPXV are mutated and predicted to be non-functional. Whereas vaccination with A33VACV did not induce in-vivo CTL activity to the predicted epitope, inhibition of virus spread in-vitro, and protection from lethal VACV challenge pointed to the B cell epitope highlighting the critical role of residue L118 and of adjacent compensatory residues in protection. This epitope's critical role in protection, as well as its modifications within the orthopoxvirus genus should be taken in context with the failure of A33 to protect against CPXV as demonstrated here. These findings should be considered when developing new subunit vaccines and monoclonal antibody based therapeutics against orthopoxviruses, especially variola virus, the etiologic agent of smallpox.
authors.affiliation: Department of Infectious Diseases, Israel Institute for Biological Research, P.O. box 19, Ness-Ziona 74100, Israel. nirp@iibr.gov.il
authors.forename: Nir
authors.initials: N
authors.lastname: Paran
authors.forename: Shlomo
authors.initials: S
authors.lastname: Lustig
authors.forename: Anat
authors.initials: A
authors.lastname: Zvi
authors.forename: Noam
authors.initials: N
authors.lastname: Erez
authors.forename: Tomer
authors.initials: T
authors.lastname: Israely
authors.forename: Sharon
authors.initials: S
authors.lastname: Melamed
authors.forename: Boaz
authors.initials: B
authors.lastname: Politi
authors.forename: David
authors.initials: D
authors.lastname: Ben-Nathan
authors.forename: Paula
authors.initials: P
authors.lastname: Schneider
authors.forename: Batel
authors.initials: B
authors.lastname: Lachmi
authors.forename: Ofir
authors.initials: O
authors.lastname: Israeli
authors.forename: Dana
authors.initials: D
authors.lastname: Stein
authors.forename: Reuven
authors.initials: R
authors.lastname: Levin
authors.forename: Udy
authors.initials: U
authors.lastname: Olshevsky
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D015608:Cowpox virus / Q000276:immunology*; D004195:Disease Models, Animal; D004337:Drug Carriers; D004481:Ectromelia virus / Q000276:immunology*; D004482:Ectromelia, Infectious / Q000517:prevention & control*; D018985:Epitopes, B-Lymphocyte / Q000235:genetics / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000235:genetics / Q000276:immunology; D005260:Female; D014644:Genetic Variation; D005822:Genetic Vectors; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D012845:Sindbis Virus / Q000235:genetics; D014615:Vaccinia / Q000517:prevention & control*; D014616:Vaccinia virus / Q000276:immunology*; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology*; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology*
chemical_list: C446940:A33R protein, Vaccinia virus; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D004337:Drug Carriers; D018985:Epitopes, B-Lymphocyte; D018984:Epitopes, T-Lymphocyte; D008562:Membrane Glycoproteins; D014759:Viral Envelope Proteins; D014765:Viral Vaccines