The pathogenicity of avian metapneumovirus subtype C wild bird isolates in domestic turkeys.
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.
Southeast Poultry Research Laboratory, Agricultural Research Service, United States Department of Agriculture, 934 College Station Road, Athens, GA 30605, USA.
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D000818:Animals; D001717:Birds / Q000821:virology; D005777:Geese / Q000821:virology; D005814:Genes, Viral; D029121:Metapneumovirus / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D018184:Paramyxoviridae Infections / Q000662:veterinary* / Q000821:virology; D011201:Poultry Diseases / Q000821:virology*; D012137:Respiratory System / Q000473:pathology / Q000821:virology; D014422:Turkeys / Q000821:virology*; D014776:Virus Cultivation