Comparative virulence of wild-type H1N1pdm09 influenza A isolates in swine.

•Three swine H1N1pdm09 viruses were compared with a human strain in pigs.•All viruses caused mild disease and resulted in viral shedding.•One swine sequence variant had lower lung and nasal swab viral titers and fewer lung lesions.•The other swine viruses caused lesions and replicated similar to the human CA/09.•Oral fluid samples were tested for viral detection in infected animals.