PostexitSurface Engineering of Retroviral/Lentiviral Vectors

Abstract

Gene delivery vectors based on retroviral or lentiviral particles are considered powerful tools for biomedicine and biotechnology applications. Such vectors require modification at the genomic level in the form of rearrangements to allow introduction of desired genes and regulatory elements (genotypic modification) as well as engineering of the physical virus particle (phenotypic modification) in order to mediate efficient and safe delivery of the genetic information to the target cell nucleus. Phenotypic modifications are typically introduced at the genomic level through genetic manipulation of the virus producing cells. However, this paper focuses on methods which allow modification of viral particle surfaces after they have exited the cell, that is, directly on the viral particles in suspension. These methods fall into three categories: (i) direct covalent chemical modification, (ii) membrane-topic reagents, and (iii) adaptor systems. Current applications of such techniques will be introduced and their advantages and disadvantages will be discussed.

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

“…In this study, we could demonstrate that modification of retroviral vector particles with a regulator of the complement system using MP leaves them less susceptible to complement attack. On a more general note, this provides further evidence for the usefulness of MP in a range of biomedical applications, from labelling of virus particles for research purposes [ 26 ] and vaccination strategies using VLPs [ 32 , 34 ] to fine-tuning vector properties for gene therapy applications [ 25 , 27 , 28 , 30 ].…”

“…Infectivity of the virus is not necessarily inhibited by the modification itself [ 26 , 29 ]; however, all post-exit incubation steps will reduce the viral half-life as a simple consequence of handling and exposure to ambient or elevated temperatures. Proteins may be converted into recombinant GPI-anchored proteins by introducing a C-terminal GPI signalling sequence (GSS) in addition to an N-terminal signal peptide (SP) [ 15 , 16 , 27 , 28 ]. While the SP directs the nascent protein towards the ER, the GSS is recognized by the TA complex and transfer of the preformed GPI anchor can occur [ 28 , 30 ].…”

Biomedical applications of glycosylphosphatidylinositol-anchored proteins

“…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 ).…”

Pros and Cons of Antigen-Presenting Cell Targeted Tumor Vaccines

“…Advantages are the flexibility, speed, and controllable modification conditions [106][107][108]. Unfortunately, the effectiveness of the chemically modified particles strongly depended on the reaction conditions of the applied modifications [109,110]. A final strategy to generate APC targeted LVs is based on the fact that binding and fusion functions of LVs can be separated over two distinct glycoproteins.…”