A comparison of the pathogenicity of avian and swine H5N1 influenza viruses in Indonesia
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Highly pathogenic avian influenza H5N1 viruses are circulating in many countries. We recently discovered that these viruses have been transmitted to pigs on multiple occasions in Indonesia. To investigate whether avian H5N1 influenza viruses adapted to mammals through their introduction into pigs, we examined the growth of avian and swine isolates in cell culture and compared their pathogenicity in mice. We found that swine isolates were less virulent to mice than avian isolates, suggesting that the viruses became attenuated during their replication in pigs. Continuous surveillance of H5N1 viruses among pigs is clearly warranted.
KeywordsInfluenza Virus Avian Influenza H5N1 Virus Avian Influenza Virus H5N1 Influenza Virus
Madin–Darby canine kidney
50% Egg infective dose
50% Tissue culture infective dose
50% Mouse lethal dose
Polymerase basic protein 2
We thank Susan Watson for editing the manuscript. This work was supported by a grant-in-aid for Specially Promoted Research and by a contract research fund for the Program of Funding Research Centers for Emerging and Reemerging Infectious Diseases from the Ministries of Education, Culture, Sports, Science, and Technology and by grants-in-aid of Health, Labor, and Welfare of Japan, by ERATO (Japan Science and Technology Agency), and by the National Institute of Allergy and Infectious Diseases Public Health Service research grants.
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