The present invention is directed to a vector and its use to generate genetically modified animals and cells. One aspect of this invention involves a vector that comprises a sperm cell and one or more polynucleotide molecules bound to a sperm cell through one or more sperm antibody linker. The sperm cell can be any animal sperm cell, preferably non-human animal such as a mouse, pig, sheep, goat, or chicken. In one preferred embodiment of this invention, the one or more polynucleotide molecules encode for a gene product that confers desired characteristics in the cells or the animals. In another preferred embodiment of this invention, the genetically modified cells are able to produce desired therapeutic proteins. The association of the sperm, linker, and the one or more polynucleotide can also occur in vitro or in vivo. In another embodiment, the genetically modified cells are transgenic chicken eggs in which one or more desired recombinant protein is expressed. In another aspect of the present invention, genetically modified cells or animals are derived from the fertilization of an animal egg cell with the vector described above. Fertilization can occur in vitro or in vivo. In one preferred embodiment, genetic modification occurs with the polynucleotide molecule integrating, wholly or partially, into the cell or animal's genome. Another aspect of the present invention includes cells, such as sperm cells or egg cells, and cell lines that are derived from these genetically modified animals or their descendants.