It is 100 years since Louis Pasteur carried out the first immunization of humans against rabies virus infection. Although great advances have been made in the development of more effective and purified vaccines, vaccines produced in adult or suckling animal nervous tissue are still in use in many countries. Cell culture systems now used for the production of human rabies vaccines include human diploid cell strain (HDCS), primary chick embryo fibroblasts, Vero cells, primary hamster, and dog or fetal bovine kidney cells.