Birth and Weaning Weights of Beef Calves A Study of Some of the Factors Influencing the

Disclosed are compositions and methods comprising vectors and a reverse genetics competent unit comprising one or more recombinant influenza viruses. Recombinant influenza viruses comprising swine RNA polymerase I promoter are disclosed. Constructs comprising swine RNA polymerase I promoter nucleic acid sequences are also provided. Methods of inducing protecting immunity with the recombinant influenza viruses are disclosed. In certain embodiments, the reverse genetics competent unit comprises pathogenic units necessary for producing pathogens de novo from a nucleotide-based vector for influenza virus in swine.