Consecutive Challenges with Geneticaly Modified H7N7 LPAIV and H7N7 HPAIV in layer hens. Issue 1 (January 2017) - Vidaña, A.; Seekings, A.H.; Núñez, A.; Slomka, M.J.; Howard, W.A.; Banks, J.; Brookes, S.M.; Brown, I.H.