Novel strategies for prevention and treatment of HIV infection

Novel strategies for prevention and treatment of HIV infection Prasit Faipenkhong Pairoaj Vonghathaipaisarn Rodjana Chunhabundit Zhang Jianjun

Outline • Introduction • Interleukin-2 • Gene therapy • Vaccines • Summary

Introduction • Problems with currently available • antiretroviral therapy • only control not cure • viral resistance • drug-drug interactions • adverse effects

Introduction • Promising strategies for treatment or • prevention • Interleukin-2 • gene therapy • vaccines

Interleukin-2

Interleukin-2 (IL-2) • cytokine • helper T cells (CD4+ T cells), cytotoxic T • cells (Tc, CD8+ T cells), natural killer cells • (NK cells) • induce proliferation and differentiation of • CD4+ T cells and cytotoxic T cells • induce B cell proliferation, stimulate • macrophage activity, increase number and • toxicity of NK cells

Interleukin-2 (IL-2) • production is decreased in HIV infected • patients

Aldesleukin • a human IL-2 derivative • absence of a N-terminal alanine, • replacement of cysteine with serine at • position 125, absence of glycosylation • possess immunological activities similar to • those observed in native IL-2

Aldesleukin • has been approved by FDA for treating • metastatic renal cell carcinoma and • metastatic melanoma • phase III clinical trials in HIV infected • patients

Clinical aspect of aldesleukin • Immunological benefits in several clinical • trials • increase CD4+ cells without sustained • increase in viral load • Subcutaneous injection is similar to • intravenous infusion • improvement in immunological parameters • Lower dosage (3 MIU/day) is still effective • increase CD4+ counts

Clinical aspect of aldesleukin • duration of intermittent therapy appears to • be important • Adversely affects virtually every organ • system requiring aggressive supportive care Flu-like symptoms swelling, redness, or lumps capillary leak syndrome (CLS)

Gene therapy

Gene therapy in HIV Ribozymes: inhibit viral replication 10-1000 fold in T-cells, and CD34 stem cell progeny (Phase I) Transdominant mutant cells transduced with vector carrying rev M10 gene survived and expressed the gene for longer time periods Intracellular immunizations: against tat, rev, reverse transcriptase

Vaccines

Vaccines • The need for HIV vaccine high infection rate, high cost of symptomatic treatment and drug therapy to stop the global HIV pandemic • Types of HIV vaccine inactivated or killed vaccines, live attenuated vaccines,subunit vaccines, live vector-based vaccines, DNA vaccines

Subunit vaccines • Components of a pathogenic organism • Advantages: stable, safe, defined • chemically and free from contaminate • proteins and nucleic acids • Disadvantage: expensive, altered • conformation of antigenic determinants • gp120 induce Ab in > 99 % of the subjects phase III clinical trials

Subunit vaccines • gp160 broaden binding Ab response and boost cellular immune responses induce strong T cell responses against a variety of HIV Ag no evidence that gp160 has efficacy as therapeutic vaccine in early stage HIV infection

Live vector-based vaccines • Live virus or bacteria vectors carrying • HIV gene • Vaccinia-env, vaccinia-env/gag/pol, • canarypox-env,canarypox-env/gag • phase I or II • Sustained expression of large amount of • HIV Ag, neutralizing Ab, CTLs responses

DNA vaccines • Research Findings chimpanzees immunized with plasmids carrying four HIV genes (env, rev, gag, pol) can be protected against HIV infection rhesus monkey immunized with plasmids carrying only env gene can be protected against HIV infection • Human studies will be held in China at early • 2001

Summary • interleukin-2: phase III • gene therapy: phase I or II • vaccines: phase III

Novel strategies for prevention and treatment of HIV infection