Abstracts (complete list) - Wissenschaft Online

Hans KUENG, Victoria LEB, Daniela HAIDERER, Graca RAPOSO, Clotilde THERY, Klaus
SCHMETTERER, Alina NEUNKIRCHNER, Christian SILLABER, Brian SEED, Winfried PICKL
A General Strategy for Decoration of Enveloped Viruses with
Functionally Active Lipid-Modified Cytokines
Viral particles preferentially incorporate extra- and intracellular constituents of host cell
lipid-rafts, a phenomenon central to pseudotyping. Based on this mechanism we have
developed a system for the predictable decoration of enveloped viruses with functionally
active cytokines that circumvents the need to modify viral proteins themselves. Human
interleukin(hIL)-2, hIL-4, hGM-CSF and murine (m)IL-2 were used as model cytokines
and fused at their C-terminus to the glycosyl phosphatidyl inositol (GPI) acceptor
sequence of the human Fc gamma receptor III (CD16b). We here show that genetically
modified cytokines are all well expressed on 293 producer cells. However, only
molecules equipped with GPI-anchors but not those linked to transmembrane/
intracellular regions of type I membrane proteins are efficiently targeted to lipid-rafts
and consequently to virus-like particles (VLP) induced by MoMLV Gag-Pol. Human IL-4::
GPI and hGM-CSF::GPI co-expressed on VLP were found to differentiate monocytes
towards dendritic cells. Apart from myeloid committed cell types, VLP-bound cytokines
also act efficiently on lymphocytes. Human IL-2::GPI strongly co-stimulated TCR/CD3
dependent T cell activation in vitro and mIL-2::GPI co-activated antigen-specific T cells
in vivo. On a molar basis, the functional activity of VLP bound hIL-2::GPI was found to
be comparable to soluble hIL-2. VLP decorated with hIL-2::GPI and co-expressing a
TCR/CD3 ligand have an IL-2 specific activity of 5 x 10 4 units/mg protein. Virus particles
decorated with lipid-modified cytokines might help to improve viral strains for
vaccination purposes, propagation of factor-dependent cell types, as well as gene
transfer by viral systems in the future.