title: Enhancement of antigen acquisition by dendritic cells and MHC class II-restricted epitope presentation to CD4+ T cells using VP22 DNA vaccine vectors that promote intercellular spreading following initial transfection.
abstract: Induction of immune responses against microbial antigens using DNA is an attractive strategy to mimic the immunity induced by live vaccines. Although DNA vaccines are efficacious in murine models, the requirement for multiple immunizations using high doses in outbred animals and humans has hindered deployment. This requirement is, in part, a result of poor vaccine spreading and suboptimal DC transfection efficiency. Incorporation of a signal that directs intercellular spreading of a DNA-encoded antigen is proposed to mimic live vaccine spreading and increase dendritic cell (DC) presentation. Bovine herpes virus 1 tegument protein, BVP22, is capable of trafficking to surrounding cells. To test the hypothesis that BVP22 enhances spreading and antigen presentation to CD4+ T cells, a DNA construct containing BVP22, fused in-frame to a sequence encoding a T cell epitope of Anaplasma marginale, was generated. A construct with reversed BVP22 sequence served as a negative control. Immunocytometric analysis of transfected primary keratinocytes, human embryonic kidney 293, COS-7, and Chinese hamster ovary cells showed that BVP22 enhanced intercellular spreading by > or = 150-fold. Flow cytometric analysis of antigen-presenting cells (APCs) positively selected from cocultures of transfected cells and APCs showed that 5% of test APCs were antigen-positive, compared with 0.6% of control APCs. Antigen-specific CD4+ T cell proliferation demonstrated that BVP22 enhanced DC antigen presentation by > or = 20-fold. This first report of the ability of BVP22 to increase DNA-encoded antigen acquisition by DCs and macrophages, with subsequent enhancement of major histocompatibility complex class II-restricted CD4+ T cell responses, supports incorporating a spreading motif in a DNA vaccine to target CD4+ T cell-dependent immunity in outbred animals.
authors.affiliation: Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040, USA. waitham@vetmed.wsu.edu
authors.forename: Waithaka
authors.initials: W
authors.lastname: Mwangi
authors.forename: Wendy C
authors.initials: WC
authors.lastname: Brown
authors.forename: Gary A
authors.initials: GA
authors.lastname: Splitter
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhuang
authors.forename: Kimberly
authors.initials: K
authors.lastname: Kegerreis
authors.forename: Guy H
authors.initials: GH
authors.lastname: Palmer
mesh_terms: D042322:Anaplasma marginale / Q000276:immunology*; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D001428:Bacterial Vaccines / Q000235:genetics / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D016466:CHO Cells; D019556:COS Cells; D002417:Cattle; D002522:Chlorocebus aethiops; D018920:Coculture Techniques; D006224:Cricetinae; D003412:Cricetulus; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology*; D018984:Epitopes, T-Lymphocyte / Q000235:genetics / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000276:immunology; D008264:Macrophages / Q000166:cytology / Q000276:immunology; D051379:Mice; D021381:Protein Transport / Q000235:genetics / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology*; D015678:Viral Structural Proteins / Q000235:genetics / Q000276:immunology*
chemical_list: D001428:Bacterial Vaccines; D018984:Epitopes, T-Lymphocyte; D000949:Histocompatibility Antigens Class II; D011993:Recombinant Fusion Proteins; D019444:Vaccines, DNA; D015678:Viral Structural Proteins; C434023:tegument protein VP22, bovine herpesvirus 1