109 Chapter 8 The Use of Lentiviral Vectors to Obtain Transgenic Rats Séverine Remy, Tuan Huy Nguyen, Séverine Ménoret, Laurent Tesson, Claire Usal, and Ignacio Anegon Abstract Lentiviral vectors are now well recognized as good vehicles for gene delivery. This is because they can efficiently transduce both dividing and post-mitotic cells, and stably integrate into the host genome allowing for long-term expression of the transgene. Their potential utility for the generation of transgenic animals has been recognized as an attractive and promising alternative to the conventional DNA- microinjection method which lacks efficiency. The initial success of lentiviral transgenesis in mice considerably broadened its use in other species, in which classical transgenic techniques are difficult, such as in the rat. In this chapter, we describe detailed procedures for both the production of human immunodeficiency virus-1 (HIV-1)-derived lentiviral vectors and for the generation of transgenic rats by injection of these vectors into the perivitelline space of fertilized one-cell eggs. Key words: Lentiviral vectors, Transgenic rat, Lentiviral transgenesis The growing interest in developing new tools and approaches to modify the genome of animals has led to the emergence of trans- genic technologies. The first transgenic mice were generated in 1976 by Jaenish, after the infection of mouse embryos with Moloney leukemia retroviruses (1). Despite the successful integra- tion and germ line transmission of exogenous DNA of retroviral origin, the absence of transgene expression in the founder animals due to retroviral DNA methylation considerably hampered the use of oncoretroviruses in animal transgenesis. Subsequently, alterna- tive methods were developed to generate transgenic animals, with particular focus on the pronuclear microinjection of DNA. Since its development by Gordon et al. in 1980 (2), this is the 1. Introduction I. Anegon (ed.), Rat Genomics: Methods and Protocols, Methods in Molecular Biology, vol. 597 DOI 10.1007/978-1-60327-389-3_8, © Humana Press, a part of Springer Science+Business Media, LLC 2010