title: Enhanced immunogenicity of SIV Gag DNA vaccines encoding chimeric proteins containing a C-terminal segment of Listeriolysin O.
abstract: We investigated the potential of the C-terminal 59-amino acid segment of Listeriolysin O (LLO) in enhancing immune responses against the SIV Gag antigen in the context of DNA immunization. Genes with codons optimized for mammalian expression were synthesized for the SIVmac239 Gag, a secreted SIV Gag protein with the tissue plasminogen antigen (tPA) signal fused to its N-terminus (tPA/Gag), as well as their corresponding chimeric proteins Gag/LLO and tPA/Gag/LLO containing the C-terminal 59 amino acids of LLO. Analysis of immune responses to these DNA constructs in a Balb/c mouse model showed that the Gag/LLO construct induced higher levels of both CD4 and CD8 T cell responses against SIV Gag, whereas the tPA/Gag construct induced higher levels of CD4 T cell responses. Moreover, immunization with the tPA/Gag/LLO construct further enhanced both CD4 and CD8 T cell responses. DNA constructs encoding secreted Gag proteins (tPA/Gag and tPA/Gag/LLO) were also more effective in eliciting antibody responses against SIV Gag. Our results demonstrate that the C-terminal segment of LLO can be effectively employed to enhance both cellular and humoral immune responses in the context of a DNA vaccine.
authors.affiliation: Department of Microbiology & Immunology, Rollins Research Center, Emory University School of Medicine, Room 3086, 1510 Clifton Road, Atlanta, GA 30322, USA.
authors.forename: Ling
authors.initials: L
authors.lastname: Ye
authors.forename: Zhigao
authors.initials: Z
authors.lastname: Bu
authors.forename: Marianne J
authors.initials: MJ
authors.lastname: Skeen
authors.forename: H Kirk
authors.initials: HK
authors.lastname: Ziegler
authors.forename: Richard W
authors.initials: RW
authors.lastname: Compans
authors.forename: Chinglai
authors.initials: C
authors.lastname: Yang
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001426:Bacterial Proteins / Q000235:genetics; D001427:Bacterial Toxins; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D003062:Codon; D005260:Female; D015870:Gene Expression; D015683:Gene Products, gag / Q000235:genetics*; D005798:Genes, Bacterial; D005814:Genes, Viral; D006360:Heat-Shock Proteins / Q000235:genetics*; D006460:Hemolysin Proteins; D007371:Interferon-gamma / Q000032:analysis; D007376:Interleukin-2 / Q000032:analysis; D051379:Mice; D008807:Mice, Inbred BALB C; D010958:Plasminogen / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics* / Q000276:immunology; D018449:SAIDS Vaccines / Q000235:genetics / Q000276:immunology*; D015302:Simian Immunodeficiency Virus / Q000235:genetics; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003062:Codon; D015683:Gene Products, gag; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D007376:Interleukin-2; D011993:Recombinant Fusion Proteins; D018449:SAIDS Vaccines; D019444:Vaccines, DNA; D007371:Interferon-gamma; D010958:Plasminogen; C038705:hlyA protein, Listeria monocytogenes