©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 12 (3): 3675-3688 (2013) Breeding of transgenic cattle for human coagulation factor IX by a combination of lentiviral system and cloning P.S. Monzani 1,3 , J.R. Sangalli 1 , T.H.C. De Bem 1,4 , F.F. Bressan 1 , P. Fantinato-Neto 1 , J.R.V. Pimentel 1 , E.H. Birgel-Junior 1 , A.M. Fontes 2 , D.T. Covas 2 and F.V. Meirelles 1 1 Departamento de Ciências Básicas, Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Pirassununga, SP, Brasil 2 Hemocentro, Universidade de São Paulo, Ribeirão Preto, SP, Brasil 3 Central Avançada em Biotecnologia da Reprodução Animal, Universidade Norte do Paraná, Londrina, PR, Brasil 4 Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil Corresponding author: P.S. Monzani E-mail: monzani.paulo@gmail.com Genet. Mol. Res. 12 (3): 3675-3688 (2013) Received July 18, 2012 Accepted November 22, 2012 Published February 28, 2013 DOI http://dx.doi.org/10.4238/2013.February.28.25 ABSTRACT. Recombinant coagulation factor IX must be produced in mammalian cells because FIX synthesis involves translational modifcations. Human cell culture-based expression of human coagulation factor IX (hFIX) is expensive, and large-scale production capacity is limited. Transgenic animals may greatly increase the yield of therapeutic proteins and reduce costs. In this study, we used a lentiviral system to obtain transgenic cells and somatic cell nuclear transfer (SCNT) to produce transgenic animals. Lentiviral vectors carrying hFIX driven by 3 bovine β-casein promoters were constructed. Bovine epithelial mammary cells were transduced by lentivirus, selected with blasticidin, plated on extracellular matrix, and