In a collaborative study, researchers at the Yerkes National Primate Research Center and Emory Vaccine Center, Emory University, have developed a new strategy to predict the immunity of a vaccine without having to expose individuals to infection.
The multidisciplinary approach, which involves immunology, genomics and bioinformatics, is a breakthrough in the development of vaccines.
Earlier, it was only possible to determine immunity or effectiveness long after vaccination, and, often, only after being exposed to infection.
YF-17D is one of the most successful vaccines ever developed and has been administered to nearly half a billion people over the last 70 years.
"A single shot of the vaccine induces immunity in many people for nearly 30 years. Despite the great success of the yellow fever vaccine, little has been known about the immunological mechanisms that make it effective," said Dr. Bali Pulendran, lead Yerkes researcher of the study and professor in the Department of Pathology and Laboratory Medicine at Emory University School of Medicine.
The researchers aimed to find out what makes such a vaccine effective so as to design new vaccines against global pandemics and emerging infections that repeat the success of this model vaccine.
YF-17D was used to predict the body's ability shortly after immunization to stimulate a strong and enduring immunity.
For the study, 15 healthy individuals with YF-17D were vaccinated and then researchers studied the T cell and antibody responses in their blood. The researchers noticed a striking variation in the responses between individuals.
Analysis of gene expression patterns in white blood cells revealed in the majority of the individuals the vaccine induced a network of genes involved in the early innate immune response against viruses.
"Using a bioinformatics approach, we were able to identify distinct gene signatures that correlated with the T cell response and the antibody response induced by the vaccine. To determine whether these gene signatures could predict immune response, we vaccinated a second group of individuals and were able to predict with up to 90 percent accuracy which of the vaccinated individuals would develop a strong T or B cell immunity to yellow fever," said Pulendran.
The researchers are now working to determine how the approach can be used to predict the effectiveness of other vaccines, including flu vaccines.
The findings could lead to the rapid evaluation of new and emerging vaccines, and the identification of individuals who are unlikely to be protected by a vaccine.
"This type of research is essential to answer fundamental questions that can lead to better vaccinations and prevention of disease. Yerkes, as one of only eight National Institutes of Health-designated national primate research centers, is uniquely positioned to carry out such diverse research," said Stuart Zola, PhD, director, Yerkes Research Center.
The study has been published in the online edition of the journal Nature Immunology.