ABSTRACT
Vaccination as a means o f preventing infectious diseases arguably has had the greatest impact on human health o f any medical intervention.1 Since the pioneer work o f Jenner and Pasteur, the development o f vaccines has been the consequence o f the uninterrupted introduction o f a series o f new technologies. The discovery o f toxoids, purification o f polysaccharides, cell culture enabling virus culture, controlled methods for attenuation o f viruses, conjugation o f polysaccharides to proteins, production o f protein vaccines in genetically-engineered cells and reassortment o f viruses have been among the basic technologies used so far in the development o f vaccines.1,2 Application o f the tools o f modern biotechnology has resulted in an array o f vaccine candidates coming from many sources and created the promise o f prevention or treatment for many more infectious and chronic diseases.3,4 It has also revolutionized the capability to engineer and produce vaccines that are potentially safer, more effective, easier to produce and less costly.5 The forthcoming new technologies form a continuum in the innovative process that has always been characteristic o f vaccine develop ment. Different new technologies are currently considered with more attention, such as
1. genetically-engineered vaccines, 2 . live vectors, 3 . nucleic acid vaccines, 4. new delivery systems or 5 . new adjuvants.1,2
This biotechnology revolution poses a tremendous challenge for traditional vaccine develop ment to provide adeauate and timely assessments so that maximal benefits might be reaped from these advances. Indeed, successful development o f vaccines is a time-intensive process requiring years o f commitment from a network o f scientists and a continuum o f regulatory and manufacturing entities.7
