Pathogenicity and transmission studies of H7N7 avian influenza virus isolated from feces of magpie origin in chickens and magpie.
An H7N7 avian influenza virus [A/Magpie/Kr/YJD174/07 (H7N7); Mp/Kr/07 virus] was isolated from magpie feces in the north-western area (Youngjongdo) of South Korea and identified as low pathogenicity by intravenous pathogenic index and amino acid sequence of cleavage site. In genetic analysis, the genome of the Mp/Kr/07 virus was the same as those of two other H7N7 viruses isolated from the Mallard ducks in Ganghwa, 5 km north of Youngjongdo, and grouped under the H7-subtype Eurasian linage with the highest similarity to recent two domestic duck isolates in South Korea. In vivo studies of the chickens and magpies, the Mp/Kr/07 virus, though did not caused any clinical signs with histological changes, could replicate in the oropharynx and cloaca of the chickens and was efficiently transmitted to contact chickens. However, the virus was restrictively identified in oropharynx of the magpies and was not spread to magpies by direct contact. These results suggest that magpie are not a biological amplifier of influenza virus and thus play a minimal role in virus transmission as intermediate host.
Kim
Min-Chul
MC
Avian Disease Division, National Veterinary Research and Quarantine Service, 480 Anyang 6-Dong, Anyang 430-757, Gyeonggi-do, South Korea.
Jeong
Ok-Mi
OM
Kang
Hyun-Mi
HM
Paek
Mi-Ra
MR
Kwon
Ji-Sun
JS
Song
Chang-Seon
CS
Kwon
Yong-Kuk
YK
Lee
Jung-Goo
JG
Kwon
Jun-Hun
JH
Lee
Youn-Jeong
YJ
D000818:Animals; D002645:Chickens; D005243:Feces / Q000821:virology*; D053126:Influenza A Virus, H7N7 Subtype / Q000302:isolation & purification / Q000472:pathogenicity*; D005585:Influenza in Birds / Q000635:transmission* / Q000821:virology*; D008969:Molecular Sequence Data; D046109:Passeriformes / Q000821:virology*; D010802:Phylogeny; D056910:Republic of Korea; D013997:Time Factors; D014779:Virus Replication / Q000502:physiology