Grant-in-Aid for Overseas Scientific Survey.
|Research Institution||Hokkaido University|
KIDA Hiroshi Hokkaido University, School of Veterinary Medicine, 獣医学部, 教授 (10109506)
河岡 義裕 セント, ジュド小児研究病院, 準教授 研究員
R.G.WEBSTER セント, ジュド小児研究病院, 主任教授研究員
岡崎 克則 東京農工大学, 農学部, 助手 (90160663)
伊藤 寿啓 北海道大学, 獣医学部, 助手 (00176348)
WEBSTER R.G. セント, ジュド小児研究病院, 主任教授 研究員
WEBSTER Robert g. St.Jude Children's Research Hospital Full Professor
KAWAOKA Yoshihiro St.Jude Children's Research Hospital Associate Professor
ITO Toshihiro Hokkaido University, School of Veterinary Medicine Instructor
OKAZAKI Katsunori Tokyo University of Agricul/Technol Instructor, Hokkaido University, School of V
|Project Fiscal Year
1993 – 1994
Completed(Fiscal Year 1994)
|Budget Amount *help
¥11,000,000 (Direct Cost : ¥11,000,000)
Fiscal Year 1994 : ¥5,000,000 (Direct Cost : ¥5,000,000)
Fiscal Year 1993 : ¥6,000,000 (Direct Cost : ¥6,000,000)
|Keywords||Influenza virus / Migratory duck / Nesting lake / Flyway / Perpetuation of virus / Phylogenetic tree / Freezing preservation / Water-born transmission / インフルエンザウイルス / 渡り鴨 / 営巣湖沼 / 渡りの飛翔路 / ウイルスの存続 / 進化系統樹 / 凍結保存 / 水系伝播 / 営巣地 / 凍結湖沼水 / 予測|
To provide information how influenza A viruses are maintained among waterfowl reservoirs at their nesting areas in the northern territory and on the mechanism of perpetuation of the viruses in nature, virological surveillance of avian influenza was continued in Alaska during their breeding season in summer from 1993 to 1994. Phylogenetic analyzes of the genes of the isolates were then carried out.
Influenza viruses were isolated mainly from fecal samples of dabbling ducks in their nesting places in central Alaska. From 541 fecal samples of ducks, 33 influenza viruses and 15 paramyxoviruses were isolated. The numbers of subtypes of influenza viruses consisted of 23 H3N8,8H4N61H2N3, and 1H7N3. Together with the results of our previous surveillance study, which was also supported by Grant-in-Aid for Scientific Research 03041013 by the Ministry of Education, Science and Culture in 1991 and 1992, the total number of influenza virus isolates from fecal samples is 108 comprising of 1 H2N3,37 H
3N8,55 H4N6,1H7N3,1 H8N2,1 H10N2,11 H10N7, and 1 H10N9 strains. These results indicate that influenza viruses have been maintained in duck population in the major breeding areas of central Alaska and that different subtypes of influenza A virus cocirculate.
Influenza viruses were also isolated from water samples of the lakes where the ducks nest. Even in autumn of 1994 when they had left for migration to south, viruses were still isolated from the lake water. The present results support the notion that influenza viruses have been maintained in waterfowl population by water-borne transmission and revealed the mechanism of year by year perpetuation of the viruses in the lakes where they breed.
Phylogenetic analysis of the NP and H3 HA genes of the representative isolates showed that they belong to the North American lineage of avian influenza viruses, suggesting that the majority of the waterfowls breeding in central Alaska migrate to North America and not to Asia. Thus phylogenetic analysis of various isolates from waterfowls made it possible to presume the migratory flyways of host birds carrying viruses.