sˈɛvɹəl stˈʌdiz dˈɛmənstɹˌeɪɾᵻd ðæt ˌɪnfluːˈɛnzə vˈaɪɹəsᵻz wɪð pˈɑːɹʃəl dᵻlˈiːʃənz ɪn ˌɛnˈɛs wˈʌn pɹˈoʊtiːnz ɑːɹ ɐtˈɛnjuːˌeɪɾᵻd ænd duːnˌɑːt kˈɔːz dɪzˈiːz, bˌʌt ɪndˈuːs ɐ pɹətˈɛktɪv ɪmjˈuːn ɹᵻspˈɑːns ɪn dˈɪfɹənt spˈiːsiːz ɪŋklˈuːdɪŋ mˈaɪs, pˈɪɡz, hˈɔːɹsᵻz, bˈɜːdz ænd mˈækæks.
Several studies demonstrated that influenza viruses with partial deletions in NS1 proteins are attenuated and do not cause disease, but induce a protective immune response in different species including mice, pigs, horses, birds and macaques.