Integrase deficient lentiviral vector: prospects for safe clinical applications

Abstract

HIV-1 derived lentiviral vector is an efficient transporter for delivering desired genetic materials into the targeted cells among many viral vectors. Genetic material transduced by lentiviral vector is integrated into the cell genome to introduce new functions, repair defective cell metabolism, and stimulate certain cell functions. Various measures have been administered in different generations of lentiviral vector systems to reduce the vector's replicating capabilities. Despite numerous demonstrations of an excellent safety profile of integrative lentiviral vectors, the precautionary approach has prompted the development of integrase-deficient versions of these vectors. The generation of integrase-deficient lentiviral vectors by abrogating integrase activity in lentiviral vector systems reduces the rate of transgenes integration into host genomes. With this feature, the integrase-deficient lentiviral vector is advantageous for therapeutic implementation and widens its clinical applications. This short review delineates the biology of HIV-1-erived lentiviral vector, generation of integrase-deficient lentiviral vector, recent studies involving integrase-deficient lentiviral vectors, limitations, and prospects for neoteric clinical use.

Keywords: Cell Reprogramming; Cell death; Gene therapy; Immunization; Integrase-deficient lentiviral vector.

Figure 1. Survey/search methodology.

Figure 2. HIV-1 genome contains nine genes.

The genes of HIV are in the central region of the pro-viral DNA. These proteins are divided into three classes: the major structural proteins (Gag, Pol, and Env); the regulatory proteins (Tat and Rev) and the accessory proteins (Vpu, Vpr, Vif, and Nef).

Figure 3. The mechanism of lentiviral transduction.

Stages of lentiviral transduction. Schematically shown are seven stages of lentiviral transduction including: (1) viral fusion to a receptor/coreceptor, (2) endocytosis of the vector & uncoating of capsid proteins, (3) release of RNA genome, (4) the positive sense RNA is converted by RT into double-stranded DNA in the cytoplasm, (5) the viral vector entry to the nucleus and & integration into the host genome, (6) fully spliced viral mRNAs can be exported from the nucleus to the cytoplasm, (7) translation.

Figure 4. A schematic representation of HIV-1 integrase (IN) and mutated amino acids to produce IDLV.

Structure of HIV-1 IN comprises three functional domains: N-terminal domain containing zinc-binding site that binds viral DNA, the catalytic core domain containing the D-D35E amino acids, and C-terminal domain containing DNA-binding site that binds non-specific target DNA-binding sites. Sites of IDLV mutations are indicated by arrows showing amino acids that give rise to mutations. Class I integrase mutations present at catalytic IN-core domain (middle) are in blue bold. Mutations affecting DNA binding and strand transfer are in black and italicized. Mutations at W235 and N120 blocks genomic binding while Q168 mutations impair vector DNA binding. H12 mutation at N-terminal domain affects IN-multimerization.

Figure 5. Possible applications of IDLV for clinical settings.

The five current applications possible for implementations in clinical settings, include gene therapy, cell reprogramming, gene editing, cell death and vaccination or immunization.