Samant went on to warn that vaccine development is a difficult and time-consuming process, exacerbated in this case by HIV's biological complexity, and that expectations must be held in check. Vaccine candidates in testing by a number of investigators employ prime-boost strategies using Vical's naked DNA delivery to prime the immune system and a range of secondary approaches to boost the immune response. Dr. Gary Nabel, Director of the Vaccine Research Center at the National Institutes of Health, is exploring the development of a prime-boost approach for an Ebola vaccine. The naked DNA technology has demonstrated the ability to induce a cellular immune response. This cellular immune response is considered a crucial element in vaccines for challenging infectious disease targets.
Conventional vaccine approaches induce only an antibody immune response.
Merck holds the exclusive worldwide license to Vical's naked DNA vaccine technology for HIV and selected other infectious disease targets. Merck is developing vaccines based on Vical's naked DNA vaccine technology to prevent and treat HIV infections. Merck is testing naked DNA vaccines for HIV in two human trials, one for uninfected volunteers and one for volunteers already infected with HIV and receiving highly active anti-retroviral therapy. The human testing began in December 1999. Vaccines are generally recognized as the most cost-effective approach for infectious disease health care.