From brain passage to cell adaptation: the road of human rabies vaccine development.

A major challenge for global rabies prevention and control is the lack of sufficient and affordable high quality vaccines. Such candidates should be pure, potent, safe, effective and economical to produce, with broad cross-reactivity against viral variants of public health and veterinary importance. The history of licensed human vaccines reviewed herein demonstrates clearly how the field has evolved to the current state of more passive development and postexposure management. Modern cell culture techniques provide adequate viral substrates for production of representative verified virus seeds. In contrast to outdated nervous tissue-based rabies vaccines, once a suitable substrate is identified, production of high titer virus results in a major qualitative and quantitative difference. Given the current scenario of only inactivated vaccines for humans, highly cell-adapted and stable, attenuated rabies viruses are ideal candidates for consideration to meet the need for seed viruses in the future.