Use of the piggyBac transposon to create HIV-1 gag transgenic insect cell lines for continuous VLP production.
BACKGROUND
Insect baculovirus-produced Human immunodeficiency virus type 1 (HIV-1) Gag virus-like-particles (VLPs) stimulate good humoral and cell-mediated immune responses in animals and are thought to be suitable as a vaccine candidate. Drawbacks to this production system include contamination of VLP preparations with baculovirus and the necessity for routine maintenance of infectious baculovirus stock. We used piggyBac transposition as a novel method to create transgenic insect cell lines for continuous VLP production as an alternative to the baculovirus system.


RESULTS
Transgenic cell lines maintained stable gag transgene integration and expression up to 100 cell passages, and although the level of VLPs produced was low compared to baculovirus-produced VLPs, they appeared similar in size and morphology to baculovirus-expressed VLPs. In a murine immunogenicity study, whereas baculovirus-produced VLPs elicited good CD4 immune responses in mice when used to boost a prime with a DNA vaccine, no boost response was elicited by transgenically produced VLPs.


CONCLUSIONS
Transgenic insect cells are stable and can produce HIV Pr55 Gag VLPs for over 100 passages: this novel result may simplify strategies aimed at making protein subunit vaccines for HIV. Immunogenicity of the Gag VLPs in mice was less than that of baculovirus-produced VLPs, which may be due to lack of baculovirus glycoprotein incorporation in the transgenic cell VLPs. Improved yield and immunogenicity of transgenic cell-produced VLPs may be achieved with the addition of further genetic elements into the piggyBac integron.
Lynch
Alisson G
AG
Department of Molecular and Cell Biology, Faculty of Science, University of Cape Town, Rondebosch, Cape Town, South Africa.
Tanzer
Fiona
F
Fraser
Malcolm J
MJ
Shephard
Enid G
EG
Williamson
Anna-Lise
AL
Rybicki
Edward P
EP
D016915:AIDS Vaccines / Q000276:immunology; D000818:Animals; D030801:Animals, Genetically Modified; D016367:Baculoviridae; D002460:Cell Line; D005260:Female; D015497:HIV-1 / Q000276:immunology; D032023:Integrons; D051379:Mice; D008807:Mice, Inbred BALB C; D010957:Plasmids; D011498:Protein Precursors / Q000276:immunology*; D018411:Spodoptera / Q000166:cytology* / Q000235:genetics; D014162:Transfection; D019076:Transgenes; D019444:Vaccines, DNA / Q000276:immunology; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000276:immunology*
D016915:AIDS Vaccines; D011498:Protein Precursors; D019444:Vaccines, DNA; D054301:gag Gene Products, Human Immunodeficiency Virus; C059767:p55 gag precursor protein, Human immunodeficiency virus 1