More than 400 scientists representing 30 countries and all levels of government, academia, and industry came together to address major issues in vaccinology at the Second Annual Conference on Vaccine Research, held March 28-30, 1999, in Bethesda, Maryland. Jointly-sponsored by the National Foundation for Infectious Diseases (NFID) and several other major health organizations (see list), topics ranged from vaccines against major global diseases, such as malaria, tuberculosis, and AIDS, to protecting against more recent threats, including biological weapons of mass destruction.

"This is an exciting time in vaccine research," said William J. Martone, MD, senior executive director of NFID and co-chair of the three-day conference. "We are discovering new vaccines, new methods for administering them, and new ways to use them. We are also gaining greater insight into immune response. All of these things are setting the stage for more and better vaccines in the future."

The conference featured innovative topic areas such as antigen presentation and processing, tumor vaccines, vaccines against candidate bioterrorist agents, and needle-free vaccination.

Alternative vaccine delivery methods are being developed as a way to make the act of immunization faster, easier, and less intrusive. Several presentations at the conference described many of the alternatives currently in development, including patches from which the skin can absorb vaccines, jet injectors which force powdered vaccines into the skin, engineered potatoes and other vegetables which contain vaccines, and nasal sprays.

Tanya M. Scharton-Kersten, PhD, senior scientist of the IOMAI Corporation in Washington, DC, discussed the results of her research in transcutaneous immunization, a method by which a vaccine is applied to the skin surface. "Transcutaneous immunization technology appears to be broadly applicable to current vaccine development," said Dr. Scharton-Kersten. This method "will be so easy to use that mass vaccination should be possible without highly trained medical professionals."

Phase I trials have already begun in healthy humans, and she is hopeful that vaccines based upon this technique will be available to the public in patch form within three to five years.

Vaccines, which have been traditionally used as a preventive measure against disease, may be broadening their scope, according to some researchers who spoke at the conference. An entire symposium was devoted to vaccines being developed specifically to treat diseases rather than prevent them. One such vaccine under development is for cancer. Jacques Banchereau, PhD, director of the Baylor Institute for Immunology Research in Dallas, and his colleagues are currently conducting preliminary trials with cancer patients trying to study the cells that are able to enhance immune response.

"We hope results of these studies will demonstrate that dendritic cells are a potentially valuable therapeutic approach in cancer and, eventually, in other conditions that affect the immune system," Dr. Banchereau said.

Dendritic cells, which are found throughout the body, are able to induce and enhance the body's natural immune response. Researchers theorize that loading these cells with tumor-derived antigens might produce rejection immune responses and cure the disease.

Researchers from the Walter Reed Army Institute of Research and the US Army Medical Research Institute of Infectious Diseases (USAMRIID) were on hand to update attendees about the military's efforts to develop vaccines against potential bioterrorist agents.

After the deadly Sarin nerve-gas incident in the Japanese subway system four years ago, the United States is well aware of the potential for terrorist use. The US Department of Defense has been developing vaccines to counteract biological threats for many years. Due to the complex nature of the countless infectious agents that could be used, government scientists have determined that identifying a generic method of vaccine delivery (or vaccine vector system) will help simplify the problem.

Jonathan F. Smith, PhD, chief of the Department of Viral Biology at USAMRIID, reported on the development of an RNA replicon vector based on an attenuated Venezuelan equine encephalitis virus (VEE). Genes from pathologic viruses are inserted into this "safe" virus to produce a vaccine. As the VEE RNA self-replicates, it expresses the genes from the other viruses.

"The hard part is identifying the most appropriate genes from the various disease-causing viruses, that is, the genes that induce a protective immune response," said Dr. Smith.

Dr. Smith explained that the altered RNA of VEE is inserted into virus particles which are then administered as a vaccine. When genes of Ebola, Lassa, Marburg, influenza, and Rift Valley fever virus were inserted into the VEE RNA vector and the resulting vaccine was given to rodents, the animals promptly demonstrated an immune response and were protected from infection with these viruses. He also noted that researchers at the University of North Carolina are using the same vector system to develop a vaccine for HIV.

"The VEE RNA replicon vector is suitable for repeated immunization against multiple agents in the same recipient," Dr. Smith said. Genes from several organisms can be inserted into a single replicon vector or multiple vectors can be mixed to produce a single vaccine.

Serving as a major international, non-commercial forum encouraging communication among the diverse disciplines of vaccinology, the conference welcomed both new and established researchers representing such specialties as infectious diseases, immunology, microbiology, pediatrics, and virology. More than 120 presentations covering basic science, product development, and clinical and field studies provided attendees with ample ground for discussion and debate.

This conference was supported, in part, by unrestricted educational grants from Aviron, Chiron Corporation, Merck Vaccine Division, Pasteur Mérieux Connaught, SmithKline Beecham Pharmaceuticals, and Wyeth-Lederle Vaccines.

• See photos from the conference