Catelli Elena, Cecchinato Mattia, Savage Carol E, Jones Richard C, Naylor Clive J
Department of Veterinary Public Health and Animal Pathology, Faculty of Veterinary Medicine, University of Bologna, Via Tolara di Sopra, 50, 40064 Ozzano Emilia (BO), Italy.
Vaccine. 2006 Oct 30;24(42-43):6476-82. doi: 10.1016/j.vaccine.2006.06.076. Epub 2006 Jul 14.
A live A type avian metapneumovirus (AMPV) vaccine which had been shown to be highly protective and short lived in experimental conditions was found to persist for longer periods in the field and to be associated with disease. Previously other factors such as possible secondary pathogens and management considerations had made it impossible to conclude whether the observed disease was a result of an increase in the vaccine virulence. In this study, an AMPV was isolated from poults on a farm which had been vaccinated with the same live A type vaccine. Full sequencing of the isolate, the vaccine and the vaccine progenitor confirmed its vaccine origin and further showed that generation of the vaccine had only involved nine substitutions of which three coded for amino acid changes. The isolated virus was inoculated into 1-day-old turkey poults in disease secure isolators and shown to cause disease with a severity similar to that caused by virulent field virus. Only two coding mutations were associated with this reversion to virulence.
一种活的A型禽偏肺病毒（AMPV）疫苗在实验条件下已被证明具有高度保护性且有效期短，但发现在实际应用中持续时间更长并与疾病相关。此前，其他因素如可能的继发病原体和管理因素使得无法确定观察到的疾病是否是疫苗毒力增加的结果。在本研究中，从一个使用相同活A型疫苗进行免疫接种的农场的雏禽中分离出一株AMPV。对分离株、疫苗及其原始毒株进行全序列分析，证实其来源于疫苗，并进一步表明疫苗的产生仅涉及9个碱基替换，其中3个导致氨基酸变化。将分离出的病毒接种到处于疾病安全隔离器中的1日龄火鸡雏禽体内，结果显示其引发的疾病严重程度与强毒野毒株相似。只有两个编码突变与这种毒力回复有关。
