Bernstein A. AIDS and the next 25 years. Science. 2008 ; 320(5877):717.
Since HIV was discovered as the cause of AIDS a quarter century ago, over 60 million people have been infected with the virus and over 25 million people have died. These numbers make the result of two “proof of concept” vaccine efficacy trials—the STEP and Phambili trials—extremely disappointing. These results reflect our still-limited knowledge of HIV, its interactions with the human immune system, and the formidable, unprecedented challenges that it poses. But evidence of immunological protection in certain experimental models of HIV in nonhuman primates, and the intriguing observation that a small proportion of HIV-infected individuals (“elite controllers”) can completely suppress the virus for years, suggest that a vaccine may be achievable. More, not less, basic and early-stage clinical research is needed. We need to understand the role of both the innate and adaptive immune responses during HIV infection. We need to make it much more attractive for young researchers, including those from other fields, to enter the HIV vaccine field. And the continued engagement of industry is essential if we are ever to have a vaccine. We know from experience with other pathogens that a vaccine is the best way to stop a virus. The only end for a journey that began 25 years ago should be the development of a safe and effective HIV vaccine.
Editors’ Notes: Disappointment can lead to sober reflection and taking stock of what should remain a firm foundation and what can and should be challenged and changed. HIV has a high degree of sequence diversity and is a phenomenal foe, striking the very cells needed for an effective immune response. The stakes are high- this is not the time to walk away.
Walker BD, Burton DR. Toward an AIDS vaccine. Science. 2008; 320(5877):760-4.
A quarter century of scientific discovery has been applied to developing an AIDS vaccine, yet this goal remains elusive. Specific characteristics of the virus, including the extreme genetic variability in circulating viral isolates worldwide, biological properties of HIV that impede immune attack, and a high mutation rate that allows for rapid escape from adaptive immune responses, render this a huge challenge. However, evidence of protection against AIDS viruses in animal models and control of HIV in humans under certain circumstances, together with scientific advances in understanding disease pathogenesis, provide a strong rationale and objective paths to continue the pursuit of an effective AIDS vaccine to stem the global epidemic.
Editors’ Notes: This review explains how the vaccines that work do so, before address ing the unique challenges for the development of an HIV vaccine. These include failure thus far to generate an immunogen to elicit effective neutralising antibodies and to identify the nature of T cell responses that could best contribute to vaccine protection against HIV. Nine critical issues and recommendations for immediate attention are laid out along with a call to pursue an HIV vaccine with greater passion than ever.
Rossi JJ, June CH, Kohn DB. Genetic therapies against HIV. Nat Biotechnol. 2007; 25(12):1444-54.
Highly active antiretroviral therapy prolongs the life of HIV-infected individuals, but it requires lifelong treatment and results in cumulative toxicities and viral-escape mutants. Gene therapy offers the promise of preventing progressive HIV infection by sustained interference with viral replication in the absence of chronic chemotherapy. Gene-targeting strategies are being developed with RNA-based agents, such as ribozymes, antisense, RNA aptamers and small interfering RNA, and protein-based agents, such as the mutant HIV Rev protein M10, fusion inhibitors and zinc-finger nucleases. Recent advances in T-cell-based strategies include gene-modified HIV-resistant T cells, lentiviral gene delivery, CD8(+) T cells, T bodies and engineered T-cell receptors. HIV-resistant hematopoietic stem cells have the potential to protect all cell types susceptible to HIV infection. The emergence of viral resistance can be addressed by therapies that use combinations of genetic agents and that inhibit both viral and host targets. Many of these strategies are being tested in ongoing and planned clinical trials.
Editors’ note: The plot thickens! Gene therapy could be a stand-alone approach or an adjuvant to drug regimens. However, most people living with HIV today are in settings with insufficient infrastructure to support such technology and viral escape will confound even gene therapy approaches. Several clinical trials testing gene transfer strategies are underway, but don’t hold your breath- this will take some time.