4Alexander D J,Brown I H. Recent zoonoses caused by influenza A viruses. Rev Sci Tech Off Int Epiz,2000, 19:197-225.
5Brown I H, Done S H,Speneer Y I. Pathogencity of a swine in- fluenza H1N1 virus antigenically distinguishable from classical and European strains. Vet Rec,1993, 132:598-602.
6Brown I H. The epidemiology and evolution of influenza viruses in pigs[J].Veterinary Microbiology,2000,(1/2):29-46.
7Castrucci M R,Donatelli I,Sidoli L. Genetic reassortment between avian and human influenza A viruses in Italian pigs[J].Virology,1993,(01):503-506.
8Brown I H. The epidemiology and evolution of influenza viruses in pigs[J].Veterinary Microbiology,2000,(01):29-46.
9Ito T,Couceiro J N,Kelm S. Molecular basis for the generation in pigs of influenza A viruses with pandemic potential[J].Journal of Virology,1998,(09):7367-7373.