title: Enhancement of antibody responses to an HIV-2 DNA envelope vaccine using an expression vector containing a constitutive transport element.
abstract: Because immune responses to DNA vaccines in humans remains suboptimal, strategies need to be devised to facilitate expression of the vaccine in vivo. One method to improve response to a DNA vaccine is to construct plasmid vectors with leader sequences and post-transcriptional elements that facilitate export of transcribed RNA. In this study, we sought to determine if a mammalian expression vector (pND-14) containing a tissue plasminogen activator (TPA) leader sequence and a constitutive transport element (CTE) from simian retrovirus was superior to other mammalian expression vectors containing a post-transcriptional regulatory element (PRE) from hepatitis B virus (pCMV-link) or a minimal mammalian expression vector (pVAX1). Toward this objective, we evaluated protein expression of the HIV-2 envelope gene (gp140) in vitro and immune responses in immunized mice. We found that pVAX1 produced three- to fourfold lower levels of gp140 in vitro (5 ng/ml) in contrast to the pCMV-link and pND-14 vectors. When we immunized groups of mice intradermally with two of the HIV-2 gp140 DNA vaccine constructs, we found that pND-14 induced higher levels of envelope-specific systemic and mucosal antibodies than pCMV-link. We conclude that expression vectors for DNA vaccines should contain TPA and CTE sequences to facilitate immune responses.
authors.affiliation: Department of Medicine, Division of Hematology and Oncology, University of California, San Francisco, USA. Christopher.locher@maxygen.com
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Locher
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Witt
authors.forename: Brittany M
authors.initials: BM
authors.lastname: Ashlock
authors.forename: Jay A
authors.initials: JA
authors.lastname: Levy
mesh_terms: D016915:AIDS Vaccines / Q000235:genetics* / Q000276:immunology*; D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis*; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D001692:Biological Transport; D002460:Cell Line; D005260:Female; D015686:Gene Products, env / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D005822:Genetic Vectors; D015498:HIV-2 / Q000276:immunology*; D018928:Immunity, Mucosal; D051379:Mice; D008807:Mice, Inbred BALB C; D011498:Protein Precursors / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology; D054299:env Gene Products, Human Immunodeficiency Virus
chemical_list: D016915:AIDS Vaccines; D000914:Antibodies, Viral; D000956:Antigens, Viral; D015686:Gene Products, env; D011498:Protein Precursors; D019444:Vaccines, DNA; D054299:env Gene Products, Human Immunodeficiency Virus; C066315:gp140 envelope protein, Human immunodeficiency virus 2