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The pathogenicity of avian metapneumovirus subtype C wild bird isolates in domestic turkeys

Cha, Ra Mi, Yu, Qingzhong, Zsak, Laszlo
Virology journal 2013 v.10 no.1 pp. 2004
Avian metapneumovirus, Branta canadensis, RNA, antibodies, antibody formation, cell culture, chickens, fibroblasts, genes, glycoproteins, immunohistochemistry, nose, nucleotide sequences, respiratory tract diseases, reverse transcriptase polymerase chain reaction, specific pathogen-free animals, trachea (vertebrates), turkeys, virulence, virus replication, viruses
BACKGROUND: Avian metapneumovirus subtype C (aMPV/C) causes severe upper respiratory disease in turkeys. Previous report revealed the presence of aMPV/C in wild birds in the southeast regions of the U.S. METHODS: In this study, aMPV/C positive oral swabs from American coots (AC) and Canada geese (CG) were passaged three times in the respiratory tract of specific pathogen free (SPF) turkeys and used as aMPV/C P3 virus isolates in subsequent studies. RESULTS: Wild bird P3 isolates showed similar growth characteristics when compared to virulent aMPV/C in chicken embryo fibroblast (CEF) cell cultures and their glycoprotein G gene sequence was closely related to the G gene of aMPV/C Colorado reference virus. Three-day-old commercial or SPF turkeys were inoculated oculonasally with wild bird aMPV/C P3 isolates. At 5 and 7 days post-inoculation (DPI), severe clinical signs were observed in both of the AC and CG virus-exposed groups. Viral RNA was detected in tracheal swabs by reverse transcriptase polymerase chain reaction (RT-PCR). In addition, immunohistochemistry showed virus replication in the nasal turbinate and trachea. All virus-exposed turkeys developed positive antibody response by 14 DPI. CONCLUSIONS: Our data demonstrate that aMPV/C wild bird isolates induced typical aMPV/C disease in the domestic turkeys.