While not exactly a "book", have you seen the May 2004 issue of Biopharm magazine? It carried an article on the science behind the world's first licensed gene therapy drug being manufactured by SiBiono -- one of China's leading gene therapy companies. The same issue also published the first English translation of guidelines for production of human gene therapy drugs -- which the Chinese govenment have now adopted as their official standard. If you can not obtain the publication readily, there is a PDF of the article on the website address shown below: http://www.nbsc.com/products/bioreactors/CelliGenPlus.asp