Velayudhan Binu T, McComb Brian, Bennett Richard S, Lopes Vanessa C, Shaw Daniel, Halvorson David A, Nagaraja Kakambi V
Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, MN, USA.
Avian Dis. 2005 Dec;49(4):520-6. doi: 10.1637/7388-052805R.1.
The objectives of the present study were to investigate the pathogenesis of a recent isolate of avian metapneumovirus (aMPV) in turkeys and to evaluate the quantitative distribution of the virus in various tissues during the course of infection. Seventy 2-week-old turkey poults were divided equally into two groups. One group was inoculated with aMPV (MN 19) with a titer of 10(5.5) TCID50 oculonasally. Birds in the second group were maintained as sham-inoculated controls. Birds showed severe clinical signs in the form of copious nasal discharge, swollen sinus, conjunctivitis, and depression from 4 days postinoculation (PI) to 12 days PI. Samples from nasal turbinates, trachea, conjunctiva, Harderian gland, infraorbital sinus, lungs, liver, and spleen were collected at 1, 3, 5, 7, 9, 11, and 14 days PI. Histopathologic lesions such as a multifocal loss of cilia were prominent in nasal turbinate and were seen from 3 to 11 days PI. Immunohistochemistry revealed the presence of aMPV from 3 to 9 days PI in nasal turbinate and trachea. Viral RNA could be detected for 14 days PI from nasal turbinate and for 9 days from trachea. In situ hybridization demonstrated the presence of aMPV from 1 to 11 days PI in nasal turbinates and from 3 to 9 days PI in the trachea. Quantitative real-time polymerase chain reaction data showed the presence of a maximum amount of virus at 3 days PI in nasal turbinate and trachea. Clinically and histopathologically, the new isolate appears to be more virulent compared to the early isolates of aMPV in the United States.
本研究的目的是调查火鸡中一种近期分离出的禽偏肺病毒（aMPV）的发病机制，并评估感染过程中该病毒在各种组织中的定量分布。70只2周龄的小火鸡被平均分为两组。一组经鼻接种滴度为10(5.5) TCID50的aMPV（MN 19）。第二组的鸡作为假接种对照。从接种后（PI）第4天到第12天，鸡出现严重的临床症状，表现为大量鼻液、鼻窦肿胀、结膜炎和精神沉郁。在接种后第1、3、5、7、9、11和14天收集来自鼻甲、气管、结膜、哈德氏腺、眶下窦、肺、肝和脾的样本。组织病理学病变，如鼻甲多灶性纤毛缺失，在接种后第3至11天很明显。免疫组织化学显示，在接种后第3至9天，鼻甲和气管中存在aMPV。从鼻甲可在接种后14天检测到病毒RNA，从气管可在接种后9天检测到。原位杂交显示，在接种后第1至11天，鼻甲中存在aMPV，在接种后第3至9天，气管中存在aMPV。定量实时聚合酶链反应数据显示，在接种后第3天，鼻甲和气管中病毒量达到最大值。临床和组织病理学结果表明，与美国早期分离的aMPV相比，这种新分离株似乎更具毒力。
