Reproduction and pathogenesis of short beak and dwarfish syndrome in Cherry Valley Pekin ducks infected with the rescued novel goose parvovirus

Since the outbreak of short beak and dwarfish syndrome (SBDS) in Cherry Valley Pekin ducks in China, novel goose parvovirus (NGPV) has been isolated. Till now, little is known about the NGPV pathogenesis toward Cherry Valley Pekin ducks. Besides, due to detection of duck circovirus co-infection in SBDS clinical cases, whether sole NGPV infection can reproduce all the typical symptoms of SBDS remains unclear. In this study, based on the NGPV isolate SDJN19, an infectious plasmid clone pJNm containing the entire SDJN19 genome was constructed. Transfection of pJNm in embryonated duck eggs resulted in generation of the infectious virus carrying the genetic marker, named rJNm. rJNm infection of 2-day-old Cherry Valley Pekin ducks reproduced all the typical signs of SBDS, including beak atrophy, tongue protrusion, and growth retardation. rJNm can infect Cherry Valley Pekin ducks through the horizontal transmission route, and the infected ducks exhibited the characteristic SBDS symptoms. A high level of serum precipitation antibodies (above 5log2) were induced in the surviving ducks, however, high viral loads were still detected in the duck organs, suggesting persistent NGPV infection in ducks. By incorporating the homologous Rep1 and VP1 gene from classical GPV, two chimeric viruses rJN-cVP1 and rJN-cRep1 were generated. Duck infection tests revealed that the non-structural protein Rep1 played a crucial role in the NGPV pathogenicity. The present result lays a solid foundation for further exploring how the Rep protein contributes to the NGPV pathogenesis.

自中国樱桃谷北京鸭暴发短喙矮小综合征（short beak and dwarfish syndrome, SBDS）以来，研究人员已分离获得新型鹅细小病毒（novel goose parvovirus, NGPV）。截至目前，学界对NGPV感染樱桃谷北京鸭的致病机制仍知之甚少。此外，由于在SBDS临床病例中检出鸭圆环病毒（duck circovirus）共感染，单一NGPV感染能否重现SBDS的全部典型症状仍不明确。本研究以NGPV分离株SDJN19为研究对象，构建了包含SDJN19全基因组的感染性质粒克隆pJNm。将pJNm转染鸭胚蛋后，获得了携带遗传标记的感染性病毒，命名为rJNm。将rJNm接种2日龄樱桃谷北京鸭，可重现SBDS的全部典型症状，包括喙萎缩、舌外伸及生长迟缓。rJNm可通过水平传播途径感染樱桃谷北京鸭，感染鸭会表现出特征性的SBDS症状。存活鸭体内可诱导产生高水平血清沉淀抗体（效价高于5log₂），但仍可在鸭组织器官中检测到高病毒载量，这表明NGPV可在鸭体内持续感染。通过引入经典鹅细小病毒（goose parvovirus, GPV）的同源Rep1与VP1基因，本研究构建了两株嵌合病毒rJN-cVP1与rJN-cRep1。鸭感染试验结果显示，非结构蛋白Rep1在NGPV的致病过程中发挥关键作用。本研究结果为进一步探究Rep蛋白如何参与NGPV致病机制奠定了坚实基础。