Immune Protection of Retroviral Vectors Upon Molecular Painting with the Complement Regulatory Protein CD59

Abstract

Glycosylphosphatidylinositol anchoring is a type of post-translational modification that allows proteins to be presented on the exterior side of the cell membrane. Purified glycosylphosphatidylinositol-anchored protein can spontaneously re-insert into lipid bilayer membranes in a process termed Molecular Painting. Here, we demonstrate the possibility of inserting purified, recombinant CD59 into virus particles produced from a murine retroviral producer cell line. CD59 is a regulator of the complement system that helps protect healthy cells from the lytic activity of the complement cascade. In this study, we could show that Molecular Painting confers protection from complement activity upon murine retroviral vector particles. Indeed, increased infectivity of CD59-modified virus particles was observed upon challenge with human serum, indicating that Molecular Painting is suitable for modulating the immune system in gene therapy or vaccination applications.Electronic supplementary materialThe online version of this article (doi:10.1007/s12033-016-9944-z) contains supplementary material, which is available to authorized users.

Biomedical applications of glycosylphosphatidylinositol-anchored proteins

“…The ability of the virus or virus vector to infect is not necessarily hindered as a consequence of insertion ( 28 ). However, caution is advised because reductions in infectivity due to the presence of additional proteins on the envelope are possible under certain circumstances ( 29 ). The process is strictly dependent on the presence of the GPI anchor lipid parts, insertion increases with increasing amounts of virus and GPI-APs, and more than one protein may be inserted at the same time ( 18 ).…”

“…The process is strictly dependent on the presence of the GPI anchor lipid parts, insertion increases with increasing amounts of virus and GPI-APs, and more than one protein may be inserted at the same time ( 18 ). Also membrane vesicles were shown to be modified by PE with GPI-APs ( 29 , 35 , 52 ). More information about recent studies will be provided in the following sections.…”

“…HR makes use of ligand-receptor interactions to trigger desired cellular responses. In most cases, this will involve a manipulation of the immune system ( 51 ), either to stimulate ( 15 , 19 , 21 , 31 ), i.e., by cytokines, or to inhibit ( 22 , 29 , 58 ), i.e., by delivery of complement regulatory factors such as CD55 or CD59.…”

“…In 2008, the first attempt at MP for the modification of V/DPs was published ( 28 ). CD59 was delivered to retro- and lentiviral vectors ( 28 ) and later shown to confer partial resistance to complement activity ( 29 ). Variants of GFP were used to modify lenti-, herpes-, and orthomyxovirus particles in a dose-dependent manner.…”

“…Also, two independent GPI-APs (CD59 and GFP) could be associated with a lentiviral vector simultaneously ( 18 ). While these approaches were mostly targeted at facilitating gene therapy using VVs ( 18 , 29 , 55 , 89 , 90 ), recently strategies for the use in vaccination were suggested ( 19 , 36 , 51 , 91 , 92 ). In these studies, influenza VLPs were generated in a recombinant baculovirus system ( 93 , 94 ) and modified, on one hand, with either GPI-anchored IL12, GM-CSF, or ICAM-1 (collectively termed GPI immunostimulatory molecules) as adjuvant agents in anti-viral immune responses ( 19 ) and, on the other hand, with GPI-HER2 as a model for protein transfer of a tumor-associated antigen for tumor vaccination ( 36 ).…”