title: Enhanced immune response against HIV-1 induced by a heterologous DNA prime-adenovirus boost vaccination using mannosylated polyethyleneimine as DNA vaccine adjuvant.
abstract: BACKGROUND
  The heterologous deoxyribonucleic acid (DNA) prime-adenovirus (AdV) boost vaccination approach has been widely applied as a promising strategy against human immunodeficiency virus (HIV)-1. However, the problem of inefficient delivery and lack of specificity of DNA vaccine remains a major issue. In this paper, to improve the transfection of DNA vaccine and realize dendritic cell targeting, we used mannosylated polyethyleneimine (man-PEI) as a DNA vector carrier.
  
  
  METHODS
  The DNA plasmid encoding antigen HIV gag fragment was constructed by polymerase chain reaction. Then the DNA plasmid was complexed with man-PEI. The in vitro transfection efficiency of man-PEI/DNA was analyzed on DC 2.4 cells. Mice were primed with 25 μg pVAX1-HIV gag plasmid complexed with man-PEI, 100 μg naked pVAX1-HIV gag plasmid, or empty pVAX1 vector and boosted by AdV encoding the same antigen. The antibody titer, CD4(+) and CD8(+) T-cell response, as well as interferon-γ and interleukin-4 levels in serum and in splenocytes culture were analyzed using flow cytometry or enzyme-linked immunosorbent assay to evaluate the immune response. To test a long-term effect of the vaccination regimen, CD8(+) memory T-cell was also detected by flow cytometry.
  
  
  RESULTS
  The pVAX1-HIV gag was constructed successfully. The in vitro transfection efficiency in dendritic cells was significantly higher than naked DNA plasmid. Compared with 100 μg naked DNA/AdV group, the immunoglobulin G2a antibody titer, T-cell response percentage, and cytokine production level induced by man-PEI/DNA/AdV group were significantly higher at a lower DNA dose. Also, the man-PEI/DNA could stimulate a memory CD8(+) T-cell response.
  
  
  CONCLUSIONS
  Owing to the adjuvant effect of man-PEI, the man-PEI/pVAX1-HIV gag priming plus AdV boosting strategy proved to be a potent vaccine candidate against HIV, which could induce a stronger immune response with a lower DNA dose.
authors.affiliation: Key Laboratory of Drug Targeting, Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu, People's Republic of China.
authors.forename: Man
authors.initials: M
authors.lastname: Li
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Jiang
authors.forename: Chaoqun
authors.initials: C
authors.lastname: Xu
authors.forename: Zhirong
authors.initials: Z
authors.lastname: Zhang
authors.forename: Xun
authors.initials: X
authors.lastname: Sun
mesh_terms: D016915:AIDS Vaccines / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D000256:Adenoviridae / Q000235:genetics; D000276:Adjuvants, Immunologic / Q000737:chemistry*; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D005260:Female; D015497:HIV-1 / Q000276:immunology*; D007371:Interferon-gamma / Q000032:analysis / Q000378:metabolism; D015847:Interleukin-4 / Q000032:analysis / Q000378:metabolism; D008358:Mannose / Q000737:chemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D011094:Polyethyleneimine / Q000737:chemistry; D013601:T-Lymphocytes / Q000276:immunology; D014162:Transfection / Q000379:methods*; D019444:Vaccines, DNA / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000276:immunology
chemical_list: D016915:AIDS Vaccines; D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D019444:Vaccines, DNA; D054301:gag Gene Products, Human Immunodeficiency Virus; D015847:Interleukin-4; D007371:Interferon-gamma; D011094:Polyethyleneimine; D008358:Mannose
keywords: DNA delivery; heterologous vaccination; human immunodeficiency virus; immune response; mannosylated polyethyleneimine