Production of Transgenic Birds Using Lentiviral Vectors

The generation of transgenic birds using lentiviral vectors is an efficient procedure that is relatively simple compared to the production of transgenic mice and other mammals. Most tools and reagents required are available in a typical molecular biology laboratory, and the procedure can be performed on a laboratory bench without special concerns for sterility. The method for avian transgenesis described here is similar to previous methods used to produce transgenic chickens by the microinjection of recombinant oncoretroviruses into the early embryo of freshly laid eggs (Bosselman et al. 1989). However, lentiviral transgenesis has a number of important advantages over previous methods. The primary advantage of using lentiviral vectors is that they are not subject to the silencing that oncoretroviral-based vectors undergo in the developing embryo. Previous studies of transgenic chickens and quails produced with oncoretroviral vectors reported low or undetectable levels of transgene expression (Mozdziak and Petitte 2004). In contrast, we and others have demonstrated that lentiviral vectors allow for high levels of transgene expression in quails and chickens (Scott BB, Lois C: Tissue-specific expression in transgenetic birds. PNAS in press). Additionally, we have shown that lentiviral vectors allow for tissue-specific expression in transgenic birds. Transgenesis using lentiviruses has been shown to be a versatile and powerful genetic tool in mice (Lois et al. 2002). In this chapter we describe the application of this tool to birds. Although this system has only been tested in chickens and quails, we anticipate that lentiviral transgenesis will be possible in a wide variety of avian species