In vitro and in vivo transport and delivery of phosphorothioate oligonucleotides with cationic liposomes

Review: Liposomes in the prophylaxis and treatment of infectious diseases

Infectious diseases remain as one of the major burdens among health communities as well as in the general public despite the advances in prevention and treatment. Although vaccination and vector eliminations have greatly prevented the transmission of these diseases, the effectiveness of these strategies is no longer guaranteed as new challenges such as drug resistance and toxicity as well as the missing effective therapeutics arise. Hence, the development of new tools to manage these challenges is anticipated, in which nano technology using liposomes as effective nanostructure is highly considered. In this review, we concentrate on the advantages of liposomes in the drug delivery system and the development of vaccine in the treatment of three major infectious diseases; tuberculosis (TB), malaria and HIV.

Specific transgene expression in HIV-infected cells using protease-cleavable transcription regulator

Gene therapy is a promising strategy for the treatment of HIV infection, but cell specificity remains an issue. Recently we have developed a new concept for a drug or gene delivery system responding to cellular signals (D-RECS) to achieve cell-specific transgene expression using a non-viral polymer-based vehicle. According to this concept, intracellular signaling enzymes, which are activated specifically in target cells, are used to trigger transgene expression. We previously applied this concept to HIV-1 protease and showed that the recombinant protease could act as a suitable signal. Here we further developed this system to achieve highly specific transgene expression in HIV-infected cells. We prepared a polymeric gene regulator grafted with a cationic peptide containing the HIV-Tat peptide via a specific substrate for HIV-1 protease. The regulator formed a stable polyplex with the transgene, suppressing its transcription. HIV-1 protease cleaved the peptide and released the transgene, which was consequently expressed specifically in activated HIV-infected cells, but remained unreleased and inactive in uninfected cells. The validity of this approach was further confirmed by applying it to the CVB1 2A protease of coxsackievirus (Picornaviridae family). This strategy should be widely applicable for specific expression of a variety of therapeutic genes in virus-infected cells.

Recent advances in delivery systems for anti-HIV1 therapy

In the last years, different non-biological and biological carrier systems have been developed for anti-HIV1 therapy. Liposomes are excellent potential anti-HIV1 carriers that have been tested with drugs, antisense oligonucleotides, ribozymes and therapeutic genes. Nanoparticles and low-density lipoproteins (LDLs) are cell-specific transporters of drugs against macrophage-specific infections such as HIV1. Through a process of protein transduction, cell-permeable peptides of natural origin or designed artificially allow the delivery of drugs and genetic material inside the cell. Erythrocyte ghosts and bacterial ghosts are a promising delivery system for therapeutic peptides and HIV vaccines. Of interest are the advances made in the field of HIV gene therapy by the use of autologous haematopoietic stem cells and viral vectors for HIV vaccines. Although important milestones have been reached in the development of carrier systems for the treatment of HIV, especially in the field of gene therapy, further clinical trials are required so that the efficiency and safety of these new systems can be guaranteed in HIV patients.

Newly designed six-membered azasugar nucleotide-containing phosphorothioate oligonucleotides as potent human immunodeficiency virus type 1 inhibitors

A series of modified oligonucleotides (ONs), characterized by a phosphorothioate (P S) backbone and a six-membered azasugar (6-AZS) as a sugar substitute in a nucleotide, were newly synthesized and assessed for their ability to inhibit human immunodeficiency virus type 1 (HIV-1) via simple treatment of HIV-1-infected cultures, without any transfection process. While unmodified P S ONs exhibited only minor anti-HIV-1 activity, the six-membered azasugar nucleotide (6-AZN)-containing P S oligonucleotides (AZPSONs) exhibited remarkable antiviral activity against HIV-1/simian-human immunodeficiency virus (SHIV) replication and syncytium formation (50% effective concentration = 0.02 to 0.2 microM). The AZPSONs exhibited little cytotoxicity at concentrations of up to 100 microM. DBM 2198, one of the most effective AZPSONs, exhibited antiviral activity against a broad spectrum of HIV-1, including T-cell-tropic, monotropic, and even drug-resistant HIV-1 variants. The anti-HIV-1 activities of DBM 2198 were similarly maintained in HIV-1-infected cultures of peripheral blood mononuclear cells. When we treated severely infected cultures with DBM 2198, syncytia disappeared completely within 2 days. Taken together, our results indicate that DBM 2198 and other AZPSONs may prove useful in the further development of safe and effective AIDS-therapeutic drugs against a broad spectrum of HIV-1 variants.

Oligonucleotides and polyribonucleotides: a review of antiviral activity

Current antiviral therapies are insufficient for treating emerging, re-emerging and established viral diseases. In an effort to find new therapeutics, oligo- and polyribonucleotides are being studied for their antiviral capabilities. Studies have shown that uniquely modified single- and double-stranded nucleic acid constructs are effective in inhibiting viral proliferation by various mechanisms. This review gives a brief history and highlights the development of oligo- and polyribonucleotides as antiviral agents primarily in the fields of interferon induction, mRNA complementation and reverse transcriptase inhibition.